Mailing List Archive

On 1/8/22 8:39 AM, James Abernathy wrote:
> With v32 coming soon, I'm looking at an upgrade of not only the software, but maybe it's time for the 11 year old hardware to be retired.  So I'm looking for thoughts on that.
>
> My current system has an SSD boot drive and 4 SATA II hard drives configured as 2 mirrors. Since they were SATA II at the time, I thought that for performance reasons, I needed 2 directories in my Recording Storage Group so the recordings would be split between mirrors.  Not sure how needed that was, but it's been working well for 10 years or so.  A secondary use of the backend is as a SMB/CIFS NAS for the rest of the house to use.
>
> Since NAS drives are reasonably priced now, I thought about a pair of Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>
> So one question is can I forget the use of a second directory in my Default Storage Group (recordings)?  My tuner is a WinTV quadHDTV PCIe card from Hauppauge and the worst load I have is 4 recordings at a time where there may be some overlap caused by back to back recordings on the same channel where the recording rules have extended time at the end.
>
> In the current backend I use ext4 on the boot SSD and the mirrors are set up as RAID 1 mirrors using mdadm. That works and I've been able to replace failed drives several times without a problem.  However, I've been researching ZFS and BTRFS and building test systems to play with both.  Since Ubuntu even allows 20.04 to be installed with ZFS, it looks promising. I really have no idea whether I should go down that path.
>
> I figure that I could probably find a miniITX motherboard with a M.2 nvme boot socket and then since the WinTV card is low-profile, I could get a smaller chassis that only holds 2 drives.
>
> Any thoughts would be appreciated.

I'll add some thoughts here. For background, I'm running with a mirrored set of nvme for boot + other storage (home directory, other bits), and a mirrored set 2 TB HD for recordings and other storage needs that need space but not performance. I'm using ZFS for all of this.

Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with. Sequential read/write speeds for HDDs tends to be pretty fast (I presume you are talking ironwolf HDD here - there are apparently also ironwolf SSDs). Based on the specs, there should be more than sufficient performance for recordings & playback.

There is the suggestion that if doing mirrors or raids, you ideally want to mix different drive models/vendors. The rationale is that if you are doing a simple mirror and running on 2 hard drives made at the same factory at the same time, these 2 drives are doing near the exact same workload. When one fails, the other will probably fail fairly soon - if you are on top of things, you can get that replacement installed before the second one fails.

ZFS has lots of nice features, but with mythtv, you probably are not going to care about most of them. It may not be worth the learning curve to set up/maintain that vs something you are familiar with.

As an aside (since this is not the case going forward), if you had 4 hard drives, you could either do a raid10 (drives are mirrored, then striped together, providing redundancy and performance, and not needing to have 2 storage directories), or raid5/raidz, where you get the capacity of 3 hard drives + 4th for redundancy, but performance on this is worse (they probably still fine for mythtv).

I would think whatever you do, you want mirrored boot drives - otherwise if the boot drive fails, you are not recording/playing anything back until you get it replaced, re-install the OS, reconfigure everything, etc. It wasn't clear to be if the miniITX option would have 2 NVME slots or not.
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> On 9 Jan 2022, at 1:49 pm, Mark Wedel <mwedel@sonic.net> wrote:
>
> On 1/8/22 8:39 AM, James Abernathy wrote:
>> With v32 coming soon, I'm looking at an upgrade of not only the software, but maybe it's time for the 11 year old hardware to be retired. So I'm looking for thoughts on that.
>> My current system has an SSD boot drive and 4 SATA II hard drives configured as 2 mirrors. Since they were SATA II at the time, I thought that for performance reasons, I needed 2 directories in my Recording Storage Group so the recordings would be split between mirrors. Not sure how needed that was, but it's been working well for 10 years or so. A secondary use of the backend is as a SMB/CIFS NAS for the rest of the house to use.
>> Since NAS drives are reasonably priced now, I thought about a pair of Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>> So one question is can I forget the use of a second directory in my Default Storage Group (recordings)? My tuner is a WinTV quadHDTV PCIe card from Hauppauge and the worst load I have is 4 recordings at a time where there may be some overlap caused by back to back recordings on the same channel where the recording rules have extended time at the end.
>> In the current backend I use ext4 on the boot SSD and the mirrors are set up as RAID 1 mirrors using mdadm. That works and I've been able to replace failed drives several times without a problem. However, I've been researching ZFS and BTRFS and building test systems to play with both. Since Ubuntu even allows 20.04 to be installed with ZFS, it looks promising. I really have no idea whether I should go down that path.
>> I figure that I could probably find a miniITX motherboard with a M.2 nvme boot socket and then since the WinTV card is low-profile, I could get a smaller chassis that only holds 2 drives.
>> Any thoughts would be appreciated.
>
> I'll add some thoughts here. For background, I'm running with a mirrored set of nvme for boot + other storage (home directory, other bits), and a mirrored set 2 TB HD for recordings and other storage needs that need space but not performance. I'm using ZFS for all of this.
>
> Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with. Sequential read/write speeds for HDDs tends to be pretty fast (I presume you are talking ironwolf HDD here - there are apparently also ironwolf SSDs). Based on the specs, there should be more than sufficient performance for recordings & playback.
>
> There is the suggestion that if doing mirrors or raids, you ideally want to mix different drive models/vendors. The rationale is that if you are doing a simple mirror and running on 2 hard drives made at the same factory at the same time, these 2 drives are doing near the exact same workload. When one fails, the other will probably fail fairly soon - if you are on top of things, you can get that replacement installed before the second one fails.
>
> ZFS has lots of nice features, but with mythtv, you probably are not going to care about most of them. It may not be worth the learning curve to set up/maintain that vs something you are familiar with.
>
> As an aside (since this is not the case going forward), if you had 4 hard drives, you could either do a raid10 (drives are mirrored, then striped together, providing redundancy and performance, and not needing to have 2 storage directories), or raid5/raidz, where you get the capacity of 3 hard drives + 4th for redundancy, but performance on this is worse (they probably still fine for mythtv).
>
> I would think whatever you do, you want mirrored boot drives - otherwise if the boot drive fails, you are not recording/playing anything back until you get it replaced, re-install the OS, reconfigure everything, etc. It wasn't clear to be if the miniITX option would have 2 NVME slots or not.

Mark , since you had lots to say I'd really value opinion.
One of my systems is on a ship in middle of ocean. Security is a total non issue - divers live in a (pressurized) chamber for 28 days. You break the system then no movies for the rest of the month and no (satphone) skype contact.
But power is notorious for just sto . . . (pping) sometimes many times a day. I've used ext4 and seldom get an unrecoverable error (clonezilla to the rescue)


2 questions

1) I can find little information on robustness of various fs. Any recommendations and why

2) Given that this is 'just tv' why all the bother with raid in leau of say 'backintime' which I find very easy and useful

Jams
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On 1/9/22 12:49 AM, Mark Wedel wrote:
> On 1/8/22 8:39 AM, James Abernathy wrote:
>> With v32 coming soon, I'm looking at an upgrade of not only the
>> software, but maybe it's time for the 11 year old hardware to be
>> retired.  So I'm looking for thoughts on that.
>>
>> My current system has an SSD boot drive and 4 SATA II hard drives
>> configured as 2 mirrors. Since they were SATA II at the time, I
>> thought that for performance reasons, I needed 2 directories in my
>> Recording Storage Group so the recordings would be split between
>> mirrors.  Not sure how needed that was, but it's been working well
>> for 10 years or so.  A secondary use of the backend is as a SMB/CIFS
>> NAS for the rest of the house to use.
>>
>> Since NAS drives are reasonably priced now, I thought about a pair of
>> Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>>
>> So one question is can I forget the use of a second directory in my
>> Default Storage Group (recordings)?  My tuner is a WinTV quadHDTV
>> PCIe card from Hauppauge and the worst load I have is 4 recordings at
>> a time where there may be some overlap caused by back to back
>> recordings on the same channel where the recording rules have
>> extended time at the end.
>>
>> In the current backend I use ext4 on the boot SSD and the mirrors are
>> set up as RAID 1 mirrors using mdadm. That works and I've been able
>> to replace failed drives several times without a problem.  However,
>> I've been researching ZFS and BTRFS and building test systems to play
>> with both.  Since Ubuntu even allows 20.04 to be installed with ZFS,
>> it looks promising. I really have no idea whether I should go down
>> that path.
>>
>> I figure that I could probably find a miniITX motherboard with a M.2
>> nvme boot socket and then since the WinTV card is low-profile, I
>> could get a smaller chassis that only holds 2 drives.
>>
>> Any thoughts would be appreciated.
>
>  I'll add some thoughts here.  For background, I'm running with a
> mirrored set of nvme for boot + other storage (home directory, other
> bits), and a mirrored set 2 TB HD for recordings and other storage
> needs that need space but not performance.  I'm using ZFS for all of
> this.
>
> Mythtv workloads are pretty kind on hard drives - it sends to be
> sequential reads and writes, which HDD are pretty good with.
> Sequential read/write speeds for HDDs tends to be pretty fast (I
> presume you are talking ironwolf HDD here - there are apparently also
> ironwolf SSDs).  Based on the specs, there should be more than
> sufficient performance for recordings & playback.
>
> There is the suggestion that if doing mirrors or raids, you ideally
> want to mix different drive models/vendors.  The rationale is that if
> you are doing a simple mirror and running on 2 hard drives made at the
> same factory at the same time, these 2 drives are doing near the exact
> same workload.  When one fails, the other will probably fail fairly
> soon - if you are on top of things, you can get that replacement
> installed before the second one fails.
>
> ZFS has lots of nice features, but with mythtv, you probably are not
> going to care about most of them.  It may not be worth the learning
> curve to set up/maintain that vs something you are familiar with.
>
> As an aside (since this is not the case going forward), if you had 4
> hard drives, you could either do a raid10 (drives are mirrored, then
> striped together, providing redundancy and performance, and not
> needing to have 2 storage directories), or raid5/raidz, where you get
> the capacity of 3 hard drives + 4th for redundancy, but performance on
> this is worse (they probably still fine for mythtv).
>
> I would think whatever you do, you want mirrored boot drives -
> otherwise if the boot drive fails, you are not recording/playing
> anything back until you get it replaced, re-install the OS,
> reconfigure everything, etc.  It wasn't clear to be if the miniITX
> option would have 2 NVME slots or not.


Thanks for you thoughts.  As to mirrored SSDs, nvme or SATA, I've heard
that RAID writes even in the unused spaces and reduces the life of an an
SSD. What have you heard?

At present, my Production MythTV/NAS boot SSD is 2.5 SATA and I have a
Conezilla image of it and it's only 16GB so I can use the cheapest
available size.

I'm built a test system yesterday with 2 identical WD Hard Drives and a
Boot SSD using Ubuntu 20.04.3 and used ZFS. The install for the OS is
standard and to create the zpool for the mirrored HDs was one simple
command. It even mounts the mirror for you after creation.  One change
is the zpool is mounted on /NAS in my case and I would have to setup
mythtv directory structure to use that. I'm going to install Mythtv
today and see how it performs.  I ran some FIO benchmarks and it's not
bad performance compared to bard metal.

I've even debated getting a real NAS like Asustor AS1104T and just use a
simple small PC with Gbe Ethernet and a PCIe slot for the tuner. But the
AS1104T is something else to manage.

Jim A


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On 1/9/22 1:31 AM, James wrote:
>
>> On 9 Jan 2022, at 1:49 pm, Mark Wedel <mwedel@sonic.net> wrote:
>>
>> On 1/8/22 8:39 AM, James Abernathy wrote:
>>> With v32 coming soon, I'm looking at an upgrade of not only the software, but maybe it's time for the 11 year old hardware to be retired. So I'm looking for thoughts on that.
>>> My current system has an SSD boot drive and 4 SATA II hard drives configured as 2 mirrors. Since they were SATA II at the time, I thought that for performance reasons, I needed 2 directories in my Recording Storage Group so the recordings would be split between mirrors. Not sure how needed that was, but it's been working well for 10 years or so. A secondary use of the backend is as a SMB/CIFS NAS for the rest of the house to use.
>>> Since NAS drives are reasonably priced now, I thought about a pair of Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>>> So one question is can I forget the use of a second directory in my Default Storage Group (recordings)? My tuner is a WinTV quadHDTV PCIe card from Hauppauge and the worst load I have is 4 recordings at a time where there may be some overlap caused by back to back recordings on the same channel where the recording rules have extended time at the end.
>>> In the current backend I use ext4 on the boot SSD and the mirrors are set up as RAID 1 mirrors using mdadm. That works and I've been able to replace failed drives several times without a problem. However, I've been researching ZFS and BTRFS and building test systems to play with both. Since Ubuntu even allows 20.04 to be installed with ZFS, it looks promising. I really have no idea whether I should go down that path.
>>> I figure that I could probably find a miniITX motherboard with a M.2 nvme boot socket and then since the WinTV card is low-profile, I could get a smaller chassis that only holds 2 drives.
>>> Any thoughts would be appreciated.
>> I'll add some thoughts here. For background, I'm running with a mirrored set of nvme for boot + other storage (home directory, other bits), and a mirrored set 2 TB HD for recordings and other storage needs that need space but not performance. I'm using ZFS for all of this.
>>
>> Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with. Sequential read/write speeds for HDDs tends to be pretty fast (I presume you are talking ironwolf HDD here - there are apparently also ironwolf SSDs). Based on the specs, there should be more than sufficient performance for recordings & playback.
>>
>> There is the suggestion that if doing mirrors or raids, you ideally want to mix different drive models/vendors. The rationale is that if you are doing a simple mirror and running on 2 hard drives made at the same factory at the same time, these 2 drives are doing near the exact same workload. When one fails, the other will probably fail fairly soon - if you are on top of things, you can get that replacement installed before the second one fails.
>>
>> ZFS has lots of nice features, but with mythtv, you probably are not going to care about most of them. It may not be worth the learning curve to set up/maintain that vs something you are familiar with.
>>
>> As an aside (since this is not the case going forward), if you had 4 hard drives, you could either do a raid10 (drives are mirrored, then striped together, providing redundancy and performance, and not needing to have 2 storage directories), or raid5/raidz, where you get the capacity of 3 hard drives + 4th for redundancy, but performance on this is worse (they probably still fine for mythtv).
>>
>> I would think whatever you do, you want mirrored boot drives - otherwise if the boot drive fails, you are not recording/playing anything back until you get it replaced, re-install the OS, reconfigure everything, etc. It wasn't clear to be if the miniITX option would have 2 NVME slots or not.
> Mark , since you had lots to say I'd really value opinion.
> One of my systems is on a ship in middle of ocean. Security is a total non issue - divers live in a (pressurized) chamber for 28 days. You break the system then no movies for the rest of the month and no (satphone) skype contact.
> But power is notorious for just sto . . . (pping) sometimes many times a day. I've used ext4 and seldom get an unrecoverable error (clonezilla to the rescue)
>
>
> 2 questions
>
> 1) I can find little information on robustness of various fs. Any recommendations and why
>
> 2) Given that this is 'just tv' why all the bother with raid in leau of say 'backintime' which I find very easy and useful
>
> Jams


I use Raid1 Mirror as a minor compromise. As to why, I don't like the
wrath of the wife when I've lost her latest copy of 'Amazing Race' or
'Survivor'. :-)

On a serious note, I also have years of home movies converted to mp4
stored along with photos on the NAS part of the system, so redundancy is
requires.  I use IDrive as my offsite backup of all of this since they
support Linux.

Jim A


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On 1/9/22 4:57 AM, Jim Abernathy wrote:
>
<trimming some of the comments>
>
>
> Thanks for you thoughts.  As to mirrored SSDs, nvme or SATA, I've heard that RAID writes even in the unused spaces and reduces the life of an an SSD. What have you heard?
>
> At present, my Production MythTV/NAS boot SSD is 2.5 SATA and I have a Conezilla image of it and it's only 16GB so I can use the cheapest available size.
>
> I'm built a test system yesterday with 2 identical WD Hard Drives and a Boot SSD using Ubuntu 20.04.3 and used ZFS. The install for the OS is standard and to create the zpool for the mirrored HDs was one simple command. It even mounts the mirror for you after creation.  One change is the zpool is mounted on /NAS in my case and I would have to setup mythtv directory structure to use that. I'm going to install Mythtv today and see how it performs.  I ran some FIO benchmarks and it's not bad performance compared to bard metal.
>
> I've even debated getting a real NAS like Asustor AS1104T and just use a simple small PC with Gbe Ethernet and a PCIe slot for the tuner. But the AS1104T is something else to manage.

I've not had an issue with SSDs running out of read/write cycles. I have had SSDs fail with other problems, so SSDs are not failure proof.

Some raid technologies require an initialization of the volume with a known set of data, so that will use up 1 write of the devices. I don't think ZFS does this, because the volume manager (raid) and filesystem are integrated together. ZFS also supports SSD operation to tell the SSDs that certain blocks are no longer in use - this then lets the SSD firmware do wear leveling by moving blocks around. I'm not sure if mdadm supports this.

Note that you can easily change the ZFS mount points, or make whatever directory structure you want (zfs create ..., zfs set mountpoint=...)

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On 1/8/22 10:31 PM, James wrote:
>
>
>> On 9 Jan 2022, at 1:49 pm, Mark Wedel <mwedel@sonic.net> wrote:
>>
>> On 1/8/22 8:39 AM, James Abernathy wrote:
>>> With v32 coming soon, I'm looking at an upgrade of not only the software, but maybe it's time for the 11 year old hardware to be retired. So I'm looking for thoughts on that.
>>> My current system has an SSD boot drive and 4 SATA II hard drives configured as 2 mirrors. Since they were SATA II at the time, I thought that for performance reasons, I needed 2 directories in my Recording Storage Group so the recordings would be split between mirrors. Not sure how needed that was, but it's been working well for 10 years or so. A secondary use of the backend is as a SMB/CIFS NAS for the rest of the house to use.
>>> Since NAS drives are reasonably priced now, I thought about a pair of Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>>> So one question is can I forget the use of a second directory in my Default Storage Group (recordings)? My tuner is a WinTV quadHDTV PCIe card from Hauppauge and the worst load I have is 4 recordings at a time where there may be some overlap caused by back to back recordings on the same channel where the recording rules have extended time at the end.
>>> In the current backend I use ext4 on the boot SSD and the mirrors are set up as RAID 1 mirrors using mdadm. That works and I've been able to replace failed drives several times without a problem. However, I've been researching ZFS and BTRFS and building test systems to play with both. Since Ubuntu even allows 20.04 to be installed with ZFS, it looks promising. I really have no idea whether I should go down that path.
>>> I figure that I could probably find a miniITX motherboard with a M.2 nvme boot socket and then since the WinTV card is low-profile, I could get a smaller chassis that only holds 2 drives.
>>> Any thoughts would be appreciated.
>>
>> I'll add some thoughts here. For background, I'm running with a mirrored set of nvme for boot + other storage (home directory, other bits), and a mirrored set 2 TB HD for recordings and other storage needs that need space but not performance. I'm using ZFS for all of this.
>>
>> Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with. Sequential read/write speeds for HDDs tends to be pretty fast (I presume you are talking ironwolf HDD here - there are apparently also ironwolf SSDs). Based on the specs, there should be more than sufficient performance for recordings & playback.
>>
>> There is the suggestion that if doing mirrors or raids, you ideally want to mix different drive models/vendors. The rationale is that if you are doing a simple mirror and running on 2 hard drives made at the same factory at the same time, these 2 drives are doing near the exact same workload. When one fails, the other will probably fail fairly soon - if you are on top of things, you can get that replacement installed before the second one fails.
>>
>> ZFS has lots of nice features, but with mythtv, you probably are not going to care about most of them. It may not be worth the learning curve to set up/maintain that vs something you are familiar with.
>>
>> As an aside (since this is not the case going forward), if you had 4 hard drives, you could either do a raid10 (drives are mirrored, then striped together, providing redundancy and performance, and not needing to have 2 storage directories), or raid5/raidz, where you get the capacity of 3 hard drives + 4th for redundancy, but performance on this is worse (they probably still fine for mythtv).
>>
>> I would think whatever you do, you want mirrored boot drives - otherwise if the boot drive fails, you are not recording/playing anything back until you get it replaced, re-install the OS, reconfigure everything, etc. It wasn't clear to be if the miniITX option would have 2 NVME slots or not.
>
> Mark , since you had lots to say I'd really value opinion.
> One of my systems is on a ship in middle of ocean. Security is a total non issue - divers live in a (pressurized) chamber for 28 days. You break the system then no movies for the rest of the month and no (satphone) skype contact.
> But power is notorious for just sto . . . (pping) sometimes many times a day. I've used ext4 and seldom get an unrecoverable error (clonezilla to the rescue)
>
>
> 2 questions
>
> 1) I can find little information on robustness of various fs. Any recommendations and why

My power here is pretty reliable. ZFS was designed to be very reliable, but I can't really say the effects of it losing power 4 times/day. In your case, I might be more tempted to use SSD (probably better able to handle power loss all as well as those spinups/spindowns) and/or invest in a UPS.

>
> 2) Given that this is 'just tv' why all the bother with raid in leau of say 'backintime' which I find very easy and useful

In my personal case, my mythtv box also acts as linux server & desktop. The extra cost of another SSD and HD to mirror everything isn't that great (just running old 2 TB drives that have ~57K power on hours, eg 6.5 years), but I don't store huge amounts of media files.

Not as much for mythtv, but for the other uses (home directory, running as a server), I've set up zfs snapshots on a daily basis - this has allowed me recovery of files that I accidentally overwrote or deleted.

That said, back in the day when I had a satellite providers PVR, it was fairly annoying losing all the recordings off of that when the hard drive failed. It would probably be less so now days (could get most of them back via streaming services). I've been using computers long enough to have enough hard drives fail that I'm willing to pay for the extra reliability.

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> On 9 Jan 2022, at 8:57 pm, Jim Abernathy <jfabernathy@gmail.com> wrote:
>
>
> On 1/9/22 12:49 AM, Mark Wedel wrote:
>> On 1/8/22 8:39 AM, James Abernathy wrote:
>>> With v32 coming soon, I'm looking at an upgrade of not only the software, but maybe it's time for the 11 year old hardware to be retired. So I'm looking for thoughts on that.
>>>
>>> My current system has an SSD boot drive and 4 SATA II hard drives configured as 2 mirrors. Since they were SATA II at the time, I thought that for performance reasons, I needed 2 directories in my Recording Storage Group so the recordings would be split between mirrors. Not sure how needed that was, but it's been working well for 10 years or so. A secondary use of the backend is as a SMB/CIFS NAS for the rest of the house to use.
>>>
>>> Since NAS drives are reasonably priced now, I thought about a pair of Seagate Ironwolf 4TB SATA III drives used in a mirrored configuration.
>>>
>>> So one question is can I forget the use of a second directory in my Default Storage Group (recordings)? My tuner is a WinTV quadHDTV PCIe card from Hauppauge and the worst load I have is 4 recordings at a time where there may be some overlap caused by back to back recordings on the same channel where the recording rules have extended time at the end.
>>>
>>> In the current backend I use ext4 on the boot SSD and the mirrors are set up as RAID 1 mirrors using mdadm. That works and I've been able to replace failed drives several times without a problem. However, I've been researching ZFS and BTRFS and building test systems to play with both. Since Ubuntu even allows 20.04 to be installed with ZFS, it looks promising. I really have no idea whether I should go down that path.
>>>
>>> I figure that I could probably find a miniITX motherboard with a M.2 nvme boot socket and then since the WinTV card is low-profile, I could get a smaller chassis that only holds 2 drives.
>>>
>>> Any thoughts would be appreciated.
>>
>> I'll add some thoughts here. For background, I'm running with a mirrored set of nvme for boot + other storage (home directory, other bits), and a mirrored set 2 TB HD for recordings and other storage needs that need space but not performance. I'm using ZFS for all of this.
>>
>> Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with. Sequential read/write speeds for HDDs tends to be pretty fast (I presume you are talking ironwolf HDD here - there are apparently also ironwolf SSDs). Based on the specs, there should be more than sufficient performance for recordings & playback.
>>
>> There is the suggestion that if doing mirrors or raids, you ideally want to mix different drive models/vendors. The rationale is that if you are doing a simple mirror and running on 2 hard drives made at the same factory at the same time, these 2 drives are doing near the exact same workload. When one fails, the other will probably fail fairly soon - if you are on top of things, you can get that replacement installed before the second one fails.
>>
>> ZFS has lots of nice features, but with mythtv, you probably are not going to care about most of them. It may not be worth the learning curve to set up/maintain that vs something you are familiar with.
>>
>> As an aside (since this is not the case going forward), if you had 4 hard drives, you could either do a raid10 (drives are mirrored, then striped together, providing redundancy and performance, and not needing to have 2 storage directories), or raid5/raidz, where you get the capacity of 3 hard drives + 4th for redundancy, but performance on this is worse (they probably still fine for mythtv).
>>
>> I would think whatever you do, you want mirrored boot drives - otherwise if the boot drive fails, you are not recording/playing anything back until you get it replaced, re-install the OS, reconfigure everything, etc. It wasn't clear to be if the miniITX option would have 2 NVME slots or not.
>
>
> Thanks for you thoughts. As to mirrored SSDs, nvme or SATA, I've heard that RAID writes even in the unused spaces and reduces the life of an an SSD. What have you heard?

Jim myth here:
SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures quote life in TBW.
The TBW spec depends directly on ssd size.
After 1/2 a year in use the projected life of my m2 is 40 years (regrettably more than mine :-)

Model Number: Samsung SSD 970 EVO Plus 2TB
Power On Hours: 3,741
Data Units Written: 29,494,374 [15.1 TB]

This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200 even 2400 TBW ssds.

James
>
> At present, my Production MythTV/NAS boot SSD is 2.5 SATA and I have a Conezilla image of it and it's only 16GB so I can use the cheapest available size.
>
> I'm built a test system yesterday with 2 identical WD Hard Drives and a Boot SSD using Ubuntu 20.04.3 and used ZFS. The install for the OS is standard and to create the zpool for the mirrored HDs was one simple command. It even mounts the mirror for you after creation. One change is the zpool is mounted on /NAS in my case and I would have to setup mythtv directory structure to use that. I'm going to install Mythtv today and see how it performs. I ran some FIO benchmarks and it's not bad performance compared to bard metal.
>
> I've even debated getting a real NAS like Asustor AS1104T and just use a simple small PC with Gbe Ethernet and a PCIe slot for the tuner. But the AS1104T is something else to manage.

One thing to keep in mind is that by the time your SSD reaches its write lifetime (even if really active - the one I installed 5 months ago is at 4% life used, which means after 9 years it will reach it limits), you can likely buy something much better for not a lot of money.

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> On 10 Jan 2022, at 1:54 pm, Mark Wedel <mwedel@sonic.net> wrote:
>
> One thing to keep in mind is that by the time your SSD reaches its write lifetime (even if really active - the one I installed 5 months ago is at 4% life used, which means after 9 years it will reach it limits), you can likely buy something much better for not a lot of money.

Mark from my experience you'd have needed to install a small (like 64G) ssd
Had you gone for a cheap say 512G SSD with a 600TBW lifetime then you'd have written 24T B or 2400G /day or 600M / sec continously for 25 years.
IE stop pin for SATA, you'd need m2.

If you were going to do that choose a say 2T drive with 2400 TBW with 100 yr lifetime.

cheap ones: https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/850evo/
more expensive: https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/970pro/
James
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On Mon, 10 Jan 2022 07:31:26 +0800, you wrote:

>Jim myth here:
>SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures quote life in TBW.
>The TBW spec depends directly on ssd size.
>After 1/2 a year in use the projected life of my m2 is 40 years (regrettably more than mine :-)
>
>Model Number: Samsung SSD 970 EVO Plus 2TB
>Power On Hours: 3,741
>Data Units Written: 29,494,374 [15.1 TB]
>
>This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200 even 2400 TBW ssds.
>
>James

Another real life example:

Model Number: Samsung SSD 950 PRO 256GB
Namespace 1 Size/Capacity: 256,060,514,304 [256 GB]
Namespace 1 Utilization: 95,130,853,376 [95.1 GB]
Namespace 1 Formatted LBA Size: 512

SMART/Health Information (NVMe Log 0x02)
Critical Warning: 0x00
Temperature: 45 Celsius
Available Spare: 100%
Available Spare Threshold: 10%
Percentage Used: 9%
Data Units Read: 360,516,312 [184 TB]
Data Units Written: 228,579,4 h42 [117 TB]
Host Read Commands: 5,169,492,455
Host Write Commands: 2,354,847,145
Controller Busy Time: 11,596
Power Cycles: 282
Power On Hours: 48,823
Unsafe Shutdowns: 133
Media and Data Integrity Errors: 0
Error Information Log Entries: 3,246

This is my main MythTV box - 5.5 years of 24/7 use on the SSD, and it
is showing 9% of lifetime writes used. It is an older SSD and the Pro
model that has better lifetime, but it gets a lot of database
activity. I am pretty happy that it will last for quite a long while
yet.

If you want to record to the SSD, then you are likely to hit the
lifetime write limit fairly rapidly. But just running MythTV and
normal Linux on an SSD and there are no problems with lifetime. You
still need to worry about it just dying unexpectedly, like any disk
drive (or any electronics, for that matter).
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On Mon, Jan 10, 2022, 3:47 AM Stephen Worthington <stephen_agent@jsw.gen.nz>
wrote:

> On Mon, 10 Jan 2022 07:31:26 +0800, you wrote:
>
> >Jim myth here:
> >SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures
> quote life in TBW.
> >The TBW spec depends directly on ssd size.
> >After 1/2 a year in use the projected life of my m2 is 40 years
> (regrettably more than mine :-)
> >
> >Model Number: Samsung SSD 970 EVO Plus 2TB
> >Power On Hours: 3,741
> >Data Units Written: 29,494,374 [15.1 TB]
> >
> >This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200
> even 2400 TBW ssds.
> >
> >James
>
> Another real life example:
>
> Model Number: Samsung SSD 950 PRO 256GB
> Namespace 1 Size/Capacity: 256,060,514,304 [256 GB]
> Namespace 1 Utilization: 95,130,853,376 [95.1 GB]
> Namespace 1 Formatted LBA Size: 512
>
> SMART/Health Information (NVMe Log 0x02)
> Critical Warning: 0x00
> Temperature: 45 Celsius
> Available Spare: 100%
> Available Spare Threshold: 10%
> Percentage Used: 9%
> Data Units Read: 360,516,312 [184 TB]
> Data Units Written: 228,579,4 h42 [117 TB]
> Host Read Commands: 5,169,492,455
> Host Write Commands: 2,354,847,145
> Controller Busy Time: 11,596
> Power Cycles: 282
> Power On Hours: 48,823
> Unsafe Shutdowns: 133
> Media and Data Integrity Errors: 0
> Error Information Log Entries: 3,246
>
> This is my main MythTV box - 5.5 years of 24/7 use on the SSD, and it
> is showing 9% of lifetime writes used. It is an older SSD and the Pro
> model that has better lifetime, but it gets a lot of database
> activity. I am pretty happy that it will last for quite a long while
> yet.
>
> If you want to record to the SSD, then you are likely to hit the
> lifetime write limit fairly rapidly. But just running MythTV and
> normal Linux on an SSD and there are no problems with lifetime. You
> still need to worry about it just dying unexpectedly, like any disk
> drive (or any electronics, for that matter).
>

What command are you using to get this SSD data.

Jim A

> On 10 Jan 2022, at 4:46 pm, Stephen Worthington <stephen_agent@jsw.gen.nz> wrote:
>
> On Mon, 10 Jan 2022 07:31:26 +0800, you wrote:
>
>> Jim myth here:
>> SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures quote life in TBW.
>> The TBW spec depends directly on ssd size.
>> After 1/2 a year in use the projected life of my m2 is 40 years (regrettably more than mine :-)
>>
>> Model Number: Samsung SSD 970 EVO Plus 2TB
>> Power On Hours: 3,741
>> Data Units Written: 29,494,374 [15.1 TB]
>>
>> This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200 even 2400 TBW ssds.
>>
>> James
>
> Another real life example:
>
> Model Number: Samsung SSD 950 PRO 256GB
> Namespace 1 Size/Capacity: 256,060,514,304 [256 GB]
> Namespace 1 Utilization: 95,130,853,376 [95.1 GB]
> Namespace 1 Formatted LBA Size: 512
>
> SMART/Health Information (NVMe Log 0x02)
> Critical Warning: 0x00
> Temperature: 45 Celsius
> Available Spare: 100%
> Available Spare Threshold: 10%
> Percentage Used: 9%
> Data Units Read: 360,516,312 [184 TB]
> Data Units Written: 228,579,4 h42 [117 TB]
> Host Read Commands: 5,169,492,455
> Host Write Commands: 2,354,847,145
> Controller Busy Time: 11,596
> Power Cycles: 282
> Power On Hours: 48,823
> Unsafe Shutdowns: 133
> Media and Data Integrity Errors: 0
> Error Information Log Entries: 3,246
>
> This is my main MythTV box - 5.5 years of 24/7 use on the SSD, and it
> is showing 9% of lifetime writes used. It is an older SSD and the Pro
> model that has better lifetime, but it gets a lot of database
> activity. I am pretty happy that it will last for quite a long while
> yet.
>
> If you want to record to the SSD, then you are likely to hit the
> lifetime write limit fairly rapidly. But just running MythTV and
> normal Linux on an SSD and there are no problems with lifetime. You
> still need to worry about it just dying unexpectedly, like any disk
> drive (or any electronics, for that matter).

I presume smartctl is giving you 10% but it is wrong!

https://www.samsung.com/au/memory-storage/nvme-ssd/950-pro-nvme-m-2-ssd-256gb-mz-v5p256bw/

200TBW of which you used 117G so 60% life used!

In 5 years buy a bigger m2 !!

Also DO NOT put the os on the storage disks. Recovery is easy unless tou can’t write to your system disk Then you need another system disk.

James

PS most ssd’s exceeded their TBH in some cases by 2x although some cases by 0.8 or 0.9 (ie shorter) mostly samsung far exceeded their spec.

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> On 10 Jan 2022, at 5:37 pm, James Abernathy <jfabernathy@gmail.com> wrote:
>
>
>
> On Mon, Jan 10, 2022, 3:47 AM Stephen Worthington <stephen_agent@jsw.gen.nz> wrote:
> On Mon, 10 Jan 2022 07:31:26 +0800, you wrote:
>
> >Jim myth here:
> >SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures quote life in TBW.
> >The TBW spec depends directly on ssd size.
> >After 1/2 a year in use the projected life of my m2 is 40 years (regrettably more than mine :-)
> >
> >Model Number: Samsung SSD 970 EVO Plus 2TB
> >Power On Hours: 3,741
> >Data Units Written: 29,494,374 [15.1 TB]
> >
> >This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200 even 2400 TBW ssds.
> >
> >James
>
> Another real life example:
>
> Model Number: Samsung SSD 950 PRO 256GB
> Namespace 1 Size/Capacity: 256,060,514,304 [256 GB]
> Namespace 1 Utilization: 95,130,853,376 [95.1 GB]
> Namespace 1 Formatted LBA Size: 512
>
> SMART/Health Information (NVMe Log 0x02)
> Critical Warning: 0x00
> Temperature: 45 Celsius
> Available Spare: 100%
> Available Spare Threshold: 10%
> Percentage Used: 9%
> Data Units Read: 360,516,312 [184 TB]
> Data Units Written: 228,579,4 h42 [117 TB]
> Host Read Commands: 5,169,492,455
> Host Write Commands: 2,354,847,145
> Controller Busy Time: 11,596
> Power Cycles: 282
> Power On Hours: 48,823
> Unsafe Shutdowns: 133
> Media and Data Integrity Errors: 0
> Error Information Log Entries: 3,246
>
> This is my main MythTV box - 5.5 years of 24/7 use on the SSD, and it
> is showing 9% of lifetime writes used. It is an older SSD and the Pro
> model that has better lifetime, but it gets a lot of database
> activity. I am pretty happy that it will last for quite a long while
> yet.
>
> If you want to record to the SSD, then you are likely to hit the
> lifetime write limit fairly rapidly. But just running MythTV and
> normal Linux on an SSD and there are no problems with lifetime. You
> still need to worry about it just dying unexpectedly, like any disk
> drive (or any electronics, for that matter).
>
> What command are you using to get this SSD data.
>

Jim you want the smartmontools
Then sudo-or-# smartctl -a /dev/disk-device
and there is heaps more online offline tests, automatic notifaction etc

James

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On 10/01/2022 08:46, Stephen Worthington wrote:
>
> If you want to record to the SSD, then you are likely to hit the
> lifetime write limit fairly rapidly. But just running MythTV and
> normal Linux on an SSD and there are no problems with lifetime. You
> still need to worry about it just dying unexpectedly, like any disk
> drive (or any electronics, for that matter).
>
I would think that is the other way around. Sure you are writing TB chunks to a recording disk but
it is written once and then read for a while until deleted. On the other hand that database is
getting *hammered* all the time as it updates e.g. seek tables. And do not forget the daily
mythfilldatabase updates! Lots and lots of small updates to files and inodes all over the place.

The one thing that you can be certain of with any (currently manufactured) SSD is that it is
guaranteed to fail. Once it reaches the lifetime limit then bang! it's gone. On the other hand, a
looked after HDD will just keep spinning.

Processor speed and memory increases are such that I don't need that extra disk write speed, not for
something as non-critical as mythtv. SSDs undoubtedly have a place for certain use cases but
thrashing a media database isn't it, in my view.

--

Mike Perkins

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On 1/10/22 4:56 AM, James Linder wrote:
> Jim you want the smartmontools
> Then sudo-or-# smartctl -a /dev/disk-device
> and there is heaps more online offline tests, automatic notifaction etc
>
> James

I just compared the output of sudo smartctl -a /dev/nvme0n1 on my newer
desktop with the SATA SSD boot drive in my Mythtv backend. Different
responses. The nvme shows:

SMART/Health Information (NVMe Log 0x02)
Critical Warning:                   0x00
Temperature:                        35 Celsius
Available Spare:                    100%
Available Spare Threshold:          10%
Percentage Used:                    0%
Data Units Read:                    9,645,524 [4.93 TB]
Data Units Written:                 8,820,656 [4.51 TB]
Host Read Commands:                 61,806,870
Host Write Commands:                92,980,201
Controller Busy Time:               427
Power Cycles:                       702
Power On Hours:                     893
Unsafe Shutdowns:                   33

However, the older SATA SSD show far less:

Just what you get from smartctl -i  None of the DUR/DUW and percentage
used. On the backend I have smarttools running test regularly and I get
output from those test, but no life data.

Jim A


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> On 10 Jan 2022, at 6:29 pm, Jim Abernathy <jfabernathy@gmail.com> wrote:
>
>
> On 1/10/22 4:56 AM, James Linder wrote:
>> Jim you want the smartmontools
>> Then sudo-or-# smartctl -a /dev/disk-device
>> and there is heaps more online offline tests, automatic notifaction etc
>>
>> James
>
> I just compared the output of sudo smartctl -a /dev/nvme0n1 on my newer desktop with the SATA SSD boot drive in my Mythtv backend. Different responses. The nvme shows:
>
> SMART/Health Information (NVMe Log 0x02)
> Critical Warning: 0x00
> Temperature: 35 Celsius
> Available Spare: 100%
> Available Spare Threshold: 10%
> Percentage Used: 0%
> Data Units Read: 9,645,524 [4.93 TB]
> Data Units Written: 8,820,656 [4.51 TB]
> Host Read Commands: 61,806,870
> Host Write Commands: 92,980,201
> Controller Busy Time: 427
> Power Cycles: 702
> Power On Hours: 893
> Unsafe Shutdowns: 33
>
> However, the older SATA SSD show far less:
>
> Just what you get from smartctl -i None of the DUR/DUW and percentage used. On the backend I have smarttools running test regularly and I get output from those test, but no life data.

I feel like a forensic chemist:

Since your power cycles are nearly the same as your power on you use that machine when you need it.
You left out the critical ID but assuming a typical large enough disk of 600TBW then life time is
600 / 4.5 times how long you've been using like this. ie say you'd been using like this for 3 months then
33 years (there go you too :-)

Mike waxes lyrical about spinning rust, but neglects the "Seagate ATA more than an interface" words of wisdom. Read what google have to say about disk life then hold the thought
If you have more than 1 disk in a box then 1 will fail.
What Seagate said is more not less relevant today!

Of course USB disks lying on the table (eg WD passport) are both cheap and pretty immune to nudging each other.

James
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On 1/10/22 6:34 AM, James wrote:
> I feel like a forensic chemist:
>
> Since your power cycles are nearly the same as your power on you use that machine when you need it.
> You left out the critical ID but assuming a typical large enough disk of 600TBW then life time is
> 600 / 4.5 times how long you've been using like this. ie say you'd been using like this for 3 months then
> 33 years (there go you too :-)
>
> Mike waxes lyrical about spinning rust, but neglects the "Seagate ATA more than an interface" words of wisdom. Read what google have to say about disk life then hold the thought
> If you have more than 1 disk in a box then 1 will fail.
> What Seagate said is more not less relevant today!
>
> Of course USB disks lying on the table (eg WD passport) are both cheap and pretty immune to nudging each other.
>
> James


So I should have given a complete output of the command. I'm not sure
where you get the 660TBW figure?


=== START OF INFORMATION SECTION ===
Model Number:                       Samsung SSD 970 EVO Plus 500GB
Serial Number:                      S58SNJ0N605998A
Firmware Version:                   2B2QEXM7
PCI Vendor/Subsystem ID:            0x144d
IEEE OUI Identifier:                0x002538
Total NVM Capacity:                 500,107,862,016 [500 GB]
Unallocated NVM Capacity:           0
Controller ID:                      4
Number of Namespaces:               1
Namespace 1 Size/Capacity:          500,107,862,016 [500 GB]
Namespace 1 Utilization:            152,041,746,432 [152 GB]
Namespace 1 Formatted LBA Size:     512
Namespace 1 IEEE EUI-64:            002538 560140802c
Local Time is:                      Mon Jan 10 06:43:56 2022 EST
Firmware Updates (0x16):            3 Slots, no Reset required
Optional Admin Commands (0x0017):   Security Format Frmw_DL Self_Test
Optional NVM Commands (0x005f):     Comp Wr_Unc DS_Mngmt Wr_Zero
Sav/Sel_Feat Timestmp
Maximum Data Transfer Size:         512 Pages
Warning  Comp. Temp. Threshold:     85 Celsius
Critical Comp. Temp. Threshold:     85 Celsius

Supported Power States
St Op     Max   Active     Idle   RL RT WL WT  Ent_Lat  Ex_Lat
 0 +     7.80W       -        -    0  0  0  0        0       0
 1 +     6.00W       -        -    1  1  1  1        0       0
 2 +     3.40W       -        -    2  2  2  2        0       0
 3 -   0.0700W       -        -    3  3  3  3      210    1200
 4 -   0.0100W       -        -    4  4  4  4     2000    8000

Supported LBA Sizes (NSID 0x1)
Id Fmt  Data  Metadt  Rel_Perf
 0 +     512       0         0

=== START OF SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

SMART/Health Information (NVMe Log 0x02)
Critical Warning:                   0x00
Temperature:                        41 Celsius
Available Spare:                    100%
Available Spare Threshold:          10%
Percentage Used:                    0%
Data Units Read:                    9,648,413 [4.93 TB]
Data Units Written:                 8,822,414 [4.51 TB]
Host Read Commands:                 61,838,930
Host Write Commands:                93,017,688
Controller Busy Time:               427
Power Cycles:                       702
Power On Hours:                     894
Unsafe Shutdowns:                   33
Media and Data Integrity Errors:    0
Error Information Log Entries:      857
Warning  Comp. Temperature Time:    0
Critical Comp. Temperature Time:    0
Temperature Sensor 1:               41 Celsius
Temperature Sensor 2:               38 Celsius

Error Information (NVMe Log 0x01, max 64 entries)
Num   ErrCount  SQId   CmdId  Status  PELoc          LBA  NSID VS
  0        857     0  0x1006  0x4004      -            0     0 -


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> On 10 Jan 2022, at 7:46 pm, Jim Abernathy <jfabernathy@gmail.com> wrote:
>
> Samsung SSD 970 EVO Plus 500GB
The new standard in sustainable performance. Get up to 600 TBW with a 5-year limited warranty for lasting performance. The 970 EVO Plus provides exceptional endurance powered by the latest V-NAND technology and Samsung's reputation for quality.

https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-evo-plus-nvme-m-2-500gb-mz-v7s500b-am/ <https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-evo-plus-nvme-m-2-500gb-mz-v7s500b-am/>

James

On Mon, Jan 10, 2022 at 8:54 AM James <jam@tigger.ws> wrote:

>
>
> On 10 Jan 2022, at 7:46 pm, Jim Abernathy <jfabernathy@gmail.com> wrote:
>
> Samsung SSD 970 EVO Plus 500GB
>
> The new standard in sustainable performance. Get up to 600 TBW with a
> 5-year limited warranty for lasting performance. The 970 EVO Plus provides
> exceptional endurance powered by the latest V-NAND technology and Samsung's
> reputation for quality.
>
>
> https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-evo-plus-nvme-m-2-500gb-mz-v7s500b-am/
>

James,

Thanks for the information. Based on 600 TBW, I could record all the
programs in Primetime on the 4 Major networks in the USA everyday plus some
assorted other stuff at an average rate of 5GB/hour and use up the SSD in
24.93 years. So if I make it to 94, then I'll have to rebuild. :-)

JIm A

On 10.01.22 11:06, Mike Perkins wrote:
> On 10/01/2022 08:46, Stephen Worthington wrote:
>>
>> If you want to record to the SSD, then you are likely to hit the
>> lifetime write limit fairly rapidly.  But just running MythTV and
>> normal Linux on an SSD and there are no problems with lifetime. You
>> still need to worry about it just dying unexpectedly, like any disk
>> drive (or any electronics, for that matter).
>>
> I would think that is the other way around. Sure you are writing TB
> chunks to a recording disk but it is written once and then read for a
> while until deleted. On the other hand that database is getting
> *hammered* all the time as it updates e.g. seek tables. And do not
> forget the daily mythfilldatabase updates! Lots and lots of small
> updates to files and inodes all over the place.
>
> The one thing that you can be certain of with any (currently
> manufactured) SSD is that it is guaranteed to fail. Once it reaches
> the lifetime limit then bang! it's gone. On the other hand, a looked
> after HDD will just keep spinning.
>
> Processor speed and memory increases are such that I don't need that
> extra disk write speed, not for something as non-critical as mythtv.
> SSDs undoubtedly have a place for certain use cases but thrashing a
> media database isn't it, in my view.
>
 My personal experience is that both SSD and disk will fail after a few
years. I got lucky, my last failure for an 8TB disk was just inside the
2 years warranty provided by the store. Not so lucky with the SSD
failure which occurred two months before.

  While it is true that the DB on SSD will write more often, there is
the advantage of being faster. As as safety measure, I always either use
mirrors (for SSD) or RAIDZ (ZFS) for the HD.

Regards,

Alain

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On Mon, Jan 10, 2022 at 11:01 AM Alain <mythuser@alain.homeunix.org> wrote:

>
> My personal experience is that both SSD and disk will fail after a few
> years. I got lucky, my last failure for an 8TB disk was just inside the
> 2 years warranty provided by the store. Not so lucky with the SSD
> failure which occurred two months before.
>
> While it is true that the DB on SSD will write more often, there is
> the advantage of being faster. As as safety measure, I always either use
> mirrors (for SSD) or RAIDZ (ZFS) for the HD.
>
> Regards,
>
> Alain
>

When you mirror your SSDs are you using mdadm Mirror or ZFS Mirror. I know
how to set up a ZFS or mdadm mirrors for data drives but If I use an SSD,
either SATA or nmve, to boot from the setup for a mirrored boot drive is a
lot more complicated from the blogs I've seen. How do you do it?

JIm A

On 10/01/2022 14:38, James Abernathy wrote:
> On Mon, Jan 10, 2022 at 8:54 AM James <jam@tigger.ws> wrote:
>
>>
>>
>> On 10 Jan 2022, at 7:46 pm, Jim Abernathy <jfabernathy@gmail.com> wrote:
>>
>> Samsung SSD 970 EVO Plus 500GB
>>
>> The new standard in sustainable performance. Get up to 600 TBW with a
>> 5-year limited warranty for lasting performance. The 970 EVO Plus provides
>> exceptional endurance powered by the latest V-NAND technology and Samsung's
>> reputation for quality.
>>
>>
>> https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-evo-plus-nvme-m-2-500gb-mz-v7s500b-am/
>>
>
> Thanks for the information. Based on 600 TBW, I could record all the
> programs in Primetime on the 4 Major networks in the USA everyday plus some
> assorted other stuff at an average rate of 5GB/hour and use up the SSD in
> 24.93 years. So if I make it to 94, then I'll have to rebuild. :-)
>
Don't overlook those magic weasel words every salesman likes to use: "up to" :)

--

Mike Perkins

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On 10/01/2022 16:00, Alain wrote:
> On 10.01.22 11:06, Mike Perkins wrote:
>> On 10/01/2022 08:46, Stephen Worthington wrote:
>>>
>>> If you want to record to the SSD, then you are likely to hit the
>>> lifetime write limit fairly rapidly.  But just running MythTV and
>>> normal Linux on an SSD and there are no problems with lifetime. You
>>> still need to worry about it just dying unexpectedly, like any disk
>>> drive (or any electronics, for that matter).
>>>
>> I would think that is the other way around. Sure you are writing TB chunks to a recording disk but
>> it is written once and then read for a while until deleted. On the other hand that database is
>> getting *hammered* all the time as it updates e.g. seek tables. And do not forget the daily
>> mythfilldatabase updates! Lots and lots of small updates to files and inodes all over the place.
>>
>> The one thing that you can be certain of with any (currently manufactured) SSD is that it is
>> guaranteed to fail. Once it reaches the lifetime limit then bang! it's gone. On the other hand, a
>> looked after HDD will just keep spinning.
>>
>> Processor speed and memory increases are such that I don't need that extra disk write speed, not
>> for something as non-critical as mythtv. SSDs undoubtedly have a place for certain use cases but
>> thrashing a media database isn't it, in my view.
>>
>  My personal experience is that both SSD and disk will fail after a few years. I got lucky, my last
> failure for an 8TB disk was just inside the 2 years warranty provided by the store. Not so lucky
> with the SSD failure which occurred two months before.
>
>   While it is true that the DB on SSD will write more often, there is the advantage of being
> faster. As as safety measure, I always either use mirrors (for SSD) or RAIDZ (ZFS) for the HD.
>
Yep. But with an SSD the end is almost guaranteed while a HDD may go on for a random, and usually
much longer, length of time. Nobody is counting the writes.

I have HDDs sitting in my box which are perfectly useable except for the fact that their interface
is no longer supported.

The other major factor is that when an SSD fails, it's dead. When an HDD fails, you have an even
chance of recovering all or most of the data before it goes completely.

--

Mike Perkins

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Mark Wedel <mwedel@sonic.net> wrote:

> Mythtv workloads are pretty kind on hard drives - it sends to be sequential reads and writes, which HDD are pretty good with.

Reads, yes sequential (mostly)
Writes, definitely not. Each recording causes a minimum of 2 seeks/second - write a bit of data, seek, update the metadata, seek, write a bit more of the stream, … Especially with multiple recordings, that can be a lot of head movement - albeit not as hard work as (say) a well worked database without adequate caching.



> James Abernathy <jfabernathy@gmail.com> wrote:

> When you mirror your SSDs are you using mdadm Mirror or ZFS Mirror. I know how to set up a ZFS or mdadm mirrors for data drives but If I use an SSD, either SATA or nmve, to boot from the setup for a mirrored boot drive is a lot more complicated from the blogs I've seen. How do you do it?

I “just do it” !

I think GRUB has dealt with this for a long time, but also as long as you keep to the legacy V1 metadata format for madam mirrored sets, each partition in the set will act (read only, for booting from) the same as the array itself. That’s because if you use the older format, the metadata is at the end of the partition and the actual data (filesystem) starts at the beginning of the partition. So you can boot from sda1, sdb1, or the array that they are part of - when I first used software raid, I don’t think GRUB did handle arrays for booting and “inertia” means that I still tend to use the V1 metadata format for my boot partition !



James Abernathy <jfabernathy@gmail.com> wrote:

> Based on 600 TBW, I could record all the programs in Primetime on the 4 Major networks in the USA everyday plus some assorted other stuff at an average rate of 5GB/hour and use up the SSD in 24.93 years. So if I make it to 94, then I'll have to rebuild. :-)

Or it could fail next week - but it’s OK, they’ll send you a nice new but blank one to replace it.
Kingston have just sent me a new 240G drive to replace one that failed. In this case I could probably recover the data because it works for a while and then “just disappears” off the bus - not that I need to as it was half of a mirrored pair.
Now, if it’s a standalone drive, with years of recordings on it - a replacement for the failed drive isn’t much compensation for it’s failure :-(


Simon

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