Mailing List Archive

On Mon, 19 Jun 2023 18:50:27 -0400, you wrote:

>Guess my talking about MythTV intrigued a friend of mine. He's thinking of
>running a backend only using leanfront on an Android box as the front end.
>Already has an HDHomerun.
>
>He has access to a Dell Optiplex 7040 Micro Tower, with Intel Core
>i5-6500T, 8 GB Memory, 256 GB SSD from work.
>
>Will that be okay as a backend only for him to experiment with?
>
>Thanks.

Not quite. You do not want to record to an SSD, especially a small
one like that. Recording files are large and they will wear out an
SSD rapidly. And on an SSD that small, they would fill it up rapidly
also. For recording, a normal hard drive should be used. One modern
hard drive should be able to record at least three programmes at once.

Apart from that, virtually any PC will do for a backend only system.
If it is wanted to run commercial skip processing, that is the only
thing that needs significant CPU power. Here in New Zealand, we
normally do not do commercial skip processing as the ad breaks here
are not usually found properly by the software. That varies around
the world - in the USA, commercial skip processing is often useful.

Linux systems have grown over the years, so now Ubuntu is not
comfortable with only 4 GiBytes of RAM, but there are still small
Linux distros that are. Having 8 GiBytes of RAM is fine until you get
up to huge numbers of recordings and tuners. I ran my MythTV box with
8 GiBytes of RAM for 10 years until a few months ago, when I gave it a
new modern motherboard with 32 GiBytes.
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> On 20 Jun 2023, at 1:11 pm, Stephen Worthington <stephen_agent@jsw.gen.nz> wrote:
>
> On Mon, 19 Jun 2023 18:50:27 -0400, you wrote:
>
>> Guess my talking about MythTV intrigued a friend of mine. He's thinking of
>> running a backend only using leanfront on an Android box as the front end.
>> Already has an HDHomerun.
>>
>> He has access to a Dell Optiplex 7040 Micro Tower, with Intel Core
>> i5-6500T, 8 GB Memory, 256 GB SSD from work.
>>
>> Will that be okay as a backend only for him to experiment with?
>>
>> Thanks.
>
> Not quite. You do not want to record to an SSD, especially a small
> one like that. Recording files are large and they will wear out an
> SSD rapidly. And on an SSD that small, they would fill it up rapidly
> also. For recording, a normal hard drive should be used. One modern
> hard drive should be able to record at least three programmes at once.
>
> Apart from that, virtually any PC will do for a backend only system.
> If it is wanted to run commercial skip processing, that is the only
> thing that needs significant CPU power. Here in New Zealand, we
> normally do not do commercial skip processing as the ad breaks here
> are not usually found properly by the software. That varies around
> the world - in the USA, commercial skip processing is often useful.
>
> Linux systems have grown over the years, so now Ubuntu is not
> comfortable with only 4 GiBytes of RAM, but there are still small
> Linux distros that are. Having 8 GiBytes of RAM is fine until you get
> up to huge numbers of recordings and tuners. I ran my MythTV box with
> 8 GiBytes of RAM for 10 years until a few months ago, when I gave it a
> new modern motherboard with 32 GiBytes.

The lifetime of SSDs depends on *size* (and the detail is complicated and messy).
I've got a 2T M2 flash. The last time I looked, after a year of use, the lifetime of the disks was greater than mine - cica 100 years.
James
A 256G drive might be 1200TBW * (.25 /2) or 150 TBW or for my usage 12 years. I had a 64G drive die in a year

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On Tue, Jun 20, 2023, 1:32 a.m. James <jam@tigger.ws> wrote:

>
>
> > On 20 Jun 2023, at 1:11 pm, Stephen Worthington <
> stephen_agent@jsw.gen.nz> wrote:
> >
> > On Mon, 19 Jun 2023 18:50:27 -0400, you wrote:
> >
> >> Guess my talking about MythTV intrigued a friend of mine. He's thinking
> of
> >> running a backend only using leanfront on an Android box as the front
> end.
> >> Already has an HDHomerun.
> >>
> >> He has access to a Dell Optiplex 7040 Micro Tower, with Intel Core
> >> i5-6500T, 8 GB Memory, 256 GB SSD from work.
> >>
> >> Will that be okay as a backend only for him to experiment with?
> >>
> >> Thanks.
> >
> > Not quite. You do not want to record to an SSD, especially a small
> > one like that. Recording files are large and they will wear out an
> > SSD rapidly. And on an SSD that small, they would fill it up rapidly
> > also. For recording, a normal hard drive should be used. One modern
> > hard drive should be able to record at least three programmes at once.
> >
> > Apart from that, virtually any PC will do for a backend only system.
> > If it is wanted to run commercial skip processing, that is the only
> > thing that needs significant CPU power. Here in New Zealand, we
> > normally do not do commercial skip processing as the ad breaks here
> > are not usually found properly by the software. That varies around
> > the world - in the USA, commercial skip processing is often useful.
> >
> > Linux systems have grown over the years, so now Ubuntu is not
> > comfortable with only 4 GiBytes of RAM, but there are still small
> > Linux distros that are. Having 8 GiBytes of RAM is fine until you get
> > up to huge numbers of recordings and tuners. I ran my MythTV box with
> > 8 GiBytes of RAM for 10 years until a few months ago, when I gave it a
> > new modern motherboard with 32 GiBytes.
>
> The lifetime of SSDs depends on *size* (and the detail is complicated and
> messy).
> I've got a 2T M2 flash. The last time I looked, after a year of use, the
> lifetime of the disks was greater than mine - cica 100 years.
> James
> A 256G drive might be 1200TBW * (.25 /2) or 150 TBW or for my usage 12
> years. I had a 64G drive die in a year
>
>
>
I guess he could always replace the SSD in the drive bracket with a 2.5
inch notebook spinning rust drive. There is an M.2 slot he could use for
boot

>
>

Am 20.06.2023 um 08:14 schrieb Ian Evans:
>
> I guess he could always replace the SSD in the drive bracket with a 2.5
> inch notebook spinning rust drive. There is an M.2 slot he could use for
> boot
>
>

Spinning drives for notebooks (2.5") used to be very slow, compared to
"normal" ones (3.5"), mostly because they spin at lower rpms. I don't
know if there still is a big difference.
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On 20/06/2023 11:04, Yann Lehmann wrote:
> Am 20.06.2023 um 08:14 schrieb Ian Evans:
>>
>> I guess he could always replace the SSD in the drive bracket with a 2.5 inch notebook spinning
>> rust drive. There is an M.2 slot he could use for boot
>>
>>
>
> Spinning drives for notebooks (2.5") used to be very slow, compared to "normal" ones (3.5"), mostly
> because they spin at lower rpms. I don't know if there still is a big difference.

2.5" drives are not just for notebooks these days. My master backend has four 2.5" WD Red NAS
drives. There are plenty that size about and not too expensive unless you spring for the enterprise
versions. For mythtv I find them perfectly adequate, able to record three programs at once while we
watch a fourth.

--

Mike Perkins


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On Tue, 20 Jun 2023 12:04:25 +0200, you wrote:

>Am 20.06.2023 um 08:14 schrieb Ian Evans:
>>
>> I guess he could always replace the SSD in the drive bracket with a 2.5
>> inch notebook spinning rust drive. There is an M.2 slot he could use for
>> boot
>>
>>
>
>Spinning drives for notebooks (2.5") used to be very slow, compared to
>"normal" ones (3.5"), mostly because they spin at lower rpms. I don't
>know if there still is a big difference.

Yes, they were very, very slow - I suspect that they are not
particularly suitable for doing recordings, especially more than one
recording at once. You can probably get faster ones now, but they
will not be cheap now that laptops are all using NVMe M.2 drives.

What you really want to use is just a normal 3.5" SATA drive. It must
not be shingled, as the shingle rewrites stop the drive from accepting
data for far too long and mythbackend will overflow its write buffers
and will drop a number of seconds of recording data whenever that
happens.

It can be on an external eSATA or USB 3 drive mount. I use both on my
laptop MythTV setup and they work fine.
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On 20 June 2023 11:04:25 BST, Yann Lehmann <aristide@free-it.ch> wrote:

>Spinning drives for notebooks (2.5") used to be very slow, compared to "normal" ones (3.5"), mostly because they spin at lower rpms. I don't know if there still is a big difference.

Just like 3.5" drives, they vary. With a previous work hat on we dealt with servers for clients - and I noticed a significant shift towards 2.5" drives. These were very much not "cheap laptop drives", with certified enterprise drives for the servers being reassuringly expensive. Typically they were 15k rpm spin speed, vs only 5400 rpm for some of the cheap laptop drive.
Spin speed is only one factor in drive performance. The other main one is track seek time - how long it takes to move the heads to the right track - and "enterprise" drives are generally much better here as well.

Simon
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On 6/19/2023 6:50 PM, Ian Evans wrote:
> Guess my talking about MythTV intrigued a friend of mine. He's
> thinking of running a backend only using leanfront on an Android box
> as the front end. Already has an HDHomerun.
>
> He has access to a Dell Optiplex 7040 Micro Tower, with Intel Core
> i5-6500T, 8 GB Memory, 256 GB SSD from work.
>
> Will that be okay as a backend only for him to experiment with?
>
> Thanks.

For experimentation, I think what he has will be just fine. If he likes
mythtv, he can either add an external USB drive or replace the SSD with
something more robust, or experiment with NAS, or back up often and be
prepared to replace the SSD when it dies, or ...

Just my $.02
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On Tue, Jun 20, 2023 at 12:24?PM faginbagin <helen.buus@gmail.com> wrote:

> On 6/19/2023 6:50 PM, Ian Evans wrote:
> > Guess my talking about MythTV intrigued a friend of mine. He's
> > thinking of running a backend only using leanfront on an Android box
> > as the front end. Already has an HDHomerun.
> >
> > He has access to a Dell Optiplex 7040 Micro Tower, with Intel Core
> > i5-6500T, 8 GB Memory, 256 GB SSD from work.
> >
> > Will that be okay as a backend only for him to experiment with?
> >
> > Thanks.
>
> For experimentation, I think what he has will be just fine. If he likes
> mythtv, he can either add an external USB drive or replace the SSD with
> something more robust, or experiment with NAS, or back up often and be
> prepared to replace the SSD when it dies, or ...
>
> Just my $.02
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> mythtv-users mailing list
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> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org
>

It's a good $.02. :-)

UPDATE: Just been informed that he may have access to an Optiplex 7010
mini-tower. I'll look it up after lunch, but I do think that one has room
for 3.5" HDDs.

> On 21 Jun 2023, at 1:13 am, Ian Evans <dheianevans@gmail.com> wrote:
>
> It's a good $.02. :-)
>
> UPDATE: Just been informed that he may have access to an Optiplex 7010 mini-tower. I'll look it up after lunch, but I do think that one has room for 3.5" HDDs.

Of passing interest, and I've not heard complaints here, and I guess the reasons are more relevant today than 20 years ago, eg Stephen saying he has 4
WD-Red drives, was Seagate's "IDE more than just an interface" paper saying

If you have more than 1 non enterprize disk in a box some will fail

Logic being driveA seeks, the bump knocks driveB off track. DriveB seeks back, the bump knocking driveA off track ...

I guess 2 1/2 drives bump less. There was also comment (somewhere in the thread) about 2 1/2s being slow. Most I've seen are 7200 rpm cica 5000 rpm for 3 1/2s
James

On 6/19/23 23:14, Ian Evans wrote:
> On Tue, Jun 20, 2023, 1:32 a.m. James <jam@tigger.ws <mailto:jam@tigger.ws>> wrote:

>
> I guess he could always replace the SSD in the drive bracket with a 2.5 inch notebook spinning rust drive. There is an M.2 slot he could use for boot

Just replacing a 256 GB SSD with a 2 TB SSD would give you 8 times the life (since it is 8 times longer), though depending on what memory technologies are being used, this might not be quite true.

It also depends on how much recording you do. If only a few programs/week (and not much live TV watching), I wouldn't be as concerned about lifetime compared to a few programs/day.

On the low count, a SSD is probably good for at least 100 write cycles - so for a 2 TB drive, that is 200 TB of recording

SSDs are advised against for security cameras, because those are recording a lot of data per day and will fairly quickly burn through capacity.

Also keep in mind expected life time - if you plan to replace the computer/drive in a few years, you may end up replacing it before you ever get near write lifetime - 200 TB = .2 TB/day for 1000 days, or 200 GB/day. So if we go back to that 256 GB drive, that would get you 25 GB/day for 1000 days, presuming the low side of 100 write cycles.

Whenever my 2 TB hitachi HDDs fail (70,000 power on hours at this point, eg 8 years), I'll likely replace them with SSDs - I just don't record stuff often enough that I'm concerned about that killing the life of the drives.

What is concerning is that my root/home drive (NVME) with about 1 year of use has written ~90 TB of data (1 TB drive). Not sure what is doing all of that - by snapshots, I can see ~150 MB/day for root filesystem, ~200 MB for home - that is well short of 240 GB/day that would account for that much data being written. So I'm not really sure what is writing all of that data.

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