Mailing List Archive

live migration, loopback devices & NFS.
Hello people,
I am trying to do is a live migration between two hosts in my subnet.
One of them (XENmaster) has NFS service with this line in
/etc/exports:

/xen 192.168.50.0/255.255.255.0(rw,sync,no_root_squash)

In the other machine (XENslave) I mount that directory with this line:

mount -t nfs XENmaster:/xen /xen

So in both machines I see the same in /xen directory. In that
directory I have the loop back devices:

XENmaster:/xen# ls -l
total 286664
-rw-r--r-- 1 root root 2139119616 2005-07-12 17:56 vmDebian2
-rw-r--r-- 1 root root 268436480 2005-06-30 18:31 vmDebian2Swap


XENslave:/xen# ls -l
total 286664
-rw-r--r-- 1 root root 2139119616 2005-07-12 17:56 vmDebian2
-rw-r--r-- 1 root root 268436480 2005-06-30 18:31 vmDebian2Swap

If I try to create a virtual machine in XENslave (The machine that is
NOT running NFS), I get that VM starts normally but when it tries to
check the filesystem it finds a problem:

IP-Config: Complete:
device=eth0, addr=192.168.50.213, mask=255.255.255.0, gw=255.255.255.255,
host=192.168.50.213, domain=, nis-domain=(none),
bootserver=1.2.3.4, rootserver=1.2.3.4, rootpath=
EXT3-fs warning: mounting fs with errors, running e2fsck is recommended
kjournald starting. Commit interval 5 seconds
EXT3 FS on hda1, internal journal
EXT3-fs: mounted filesystem with ordered data mode.
VFS: Mounted root (ext3 filesystem).
Freeing unused kernel memory: 112k freed
INIT: version 2.86 booting
Activating swap.
Checking root file system...
fsck 1.37 (21-Mar-2005)
/dev/shm/root: The filesystem size (according to the superblock) is
524288 blocks
The physical size of the device is 522246 blocks
Either the superblock or the partition table is likely to be corrupt!


/dev/shm/root: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
(i.e., without -a or -p options)

fsck failed. Please repair manually and reboot. Please note
that the root file system is currently mounted read-only. To
remount it read-write:

# mount -n -o remount,rw /

CONTROL-D will exit from this shell and REBOOT the system.

Press enter for maintenance
(or type Control-D to continue):


It seems that something is wrong with the filesystem block size:

/dev/shm/root: The filesystem size (according to the superblock) is
524288 blocks
The physical size of the device is 522246 blocks
Either the superblock or the partition table is likely to be corrupt!

But I don't really know how to resolve this. It seems that there's a
problem with NFS and loopback devices, but how do I do this without
loopback devices? I can create VMs with LVM but, how do I share them?
What do you do? Has anybody there used live migration? How did you get
it?

Thank you for your help.
MIguel.

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Re: live migration, loopback devices & NFS. [ In reply to ]
Ok, now I think that it doesn't has to do with Xen. It has to do with
NFS. I think that the problem is that I am using NFSv2, that can only
handle files smaller than 2Gb. So I will have to use NFSv3.

Take a look at this post:
http://lists.freebsd.org/pipermail/freebsd-questions/2004-June/048294.html

In the nfs client I type:


XENmaster:/# nfsstat
Client rpc stats:
calls retrans authrefrsh
17 0 0
Client nfs v2:
null getattr setattr root lookup readlink
0 0% 7 41% 0 0% 0 0% 4 23% 0 0%
read wrcache write create remove rename
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
link symlink mkdir rmdir readdir fsstat
0 0% 0 0% 0 0% 0 0% 3 17% 3 17%

Client nfs v3:
null getattr setattr lookup access readlink
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
read write create mkdir symlink mknod
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
remove rmdir rename link readdir readdirplus
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
fsstat fsinfo pathconf commit
0 0% 0 0% 0 0% 0 0%


All the traffic is NFSv2. Do you know how can I use NFSv3? I added
this to my /etc/fstab 's nfs line option:
soft,noauto,nolock,rsize=1024,wsize=1024,intr,retry=10,nfsvers=3

But it doesn't works, it tells me that I can only use nfsvers=1 or nfsvers=2.

Thank you!!!!!
Regards,

Miguel.


















On 7/12/05, Miguel Gómez <elmiguelonmakinon@gmail.com> wrote:
> Hello people,
> I am trying to do is a live migration between two hosts in my subnet.
> One of them (XENmaster) has NFS service with this line in
> /etc/exports:
>
> /xen 192.168.50.0/255.255.255.0(rw,sync,no_root_squash)
>
> In the other machine (XENslave) I mount that directory with this line:
>
> mount -t nfs XENmaster:/xen /xen
>
> So in both machines I see the same in /xen directory. In that
> directory I have the loop back devices:
>
> XENmaster:/xen# ls -l
> total 286664
> -rw-r--r-- 1 root root 2139119616 2005-07-12 17:56 vmDebian2
> -rw-r--r-- 1 root root 268436480 2005-06-30 18:31 vmDebian2Swap
>
>
> XENslave:/xen# ls -l
> total 286664
> -rw-r--r-- 1 root root 2139119616 2005-07-12 17:56 vmDebian2
> -rw-r--r-- 1 root root 268436480 2005-06-30 18:31 vmDebian2Swap
>
> If I try to create a virtual machine in XENslave (The machine that is
> NOT running NFS), I get that VM starts normally but when it tries to
> check the filesystem it finds a problem:
>
> IP-Config: Complete:
> device=eth0, addr=192.168.50.213, mask=255.255.255.0, gw=255.255.255.255,
> host=192.168.50.213, domain=, nis-domain=(none),
> bootserver=1.2.3.4, rootserver=1.2.3.4, rootpath=
> EXT3-fs warning: mounting fs with errors, running e2fsck is recommended
> kjournald starting. Commit interval 5 seconds
> EXT3 FS on hda1, internal journal
> EXT3-fs: mounted filesystem with ordered data mode.
> VFS: Mounted root (ext3 filesystem).
> Freeing unused kernel memory: 112k freed
> INIT: version 2.86 booting
> Activating swap.
> Checking root file system...
> fsck 1.37 (21-Mar-2005)
> /dev/shm/root: The filesystem size (according to the superblock) is
> 524288 blocks
> The physical size of the device is 522246 blocks
> Either the superblock or the partition table is likely to be corrupt!
>
>
> /dev/shm/root: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
> (i.e., without -a or -p options)
>
> fsck failed. Please repair manually and reboot. Please note
> that the root file system is currently mounted read-only. To
> remount it read-write:
>
> # mount -n -o remount,rw /
>
> CONTROL-D will exit from this shell and REBOOT the system.
>
> Press enter for maintenance
> (or type Control-D to continue):
>
>
> It seems that something is wrong with the filesystem block size:
>
> /dev/shm/root: The filesystem size (according to the superblock) is
> 524288 blocks
> The physical size of the device is 522246 blocks
> Either the superblock or the partition table is likely to be corrupt!
>
> But I don't really know how to resolve this. It seems that there's a
> problem with NFS and loopback devices, but how do I do this without
> loopback devices? I can create VMs with LVM but, how do I share them?
> What do you do? Has anybody there used live migration? How did you get
> it?
>
> Thank you for your help.
> MIguel.
>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
Re: live migration, loopback devices & NFS. [ In reply to ]
I know the problem, Im using large files (longer than 2Gb) with NFS
and it doesn't work becouse of that. When I reduced the loopback
devices to 1GB, and it works. Now I need to know how to use NFSv3 so I
can use longer files.

.....



Good news. The problems is that I was using nfs-user-server that only
supports NFSv2 (at least in my Debian machine). I installed
nfs-kernel-server, and now I can use larger files than 2GB.

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