can't mount XFS from a read-only device

can't mount XFS from a read-only device

[Emmanuel Florac]

Hello all, 

I'm using a RAID enclosure that provides read-only snapshots. It works
perfectly fine using JFS.
But with XFS, I keep trying and it keeps failing :

XFS mounting filesystem sdb

Ending clean XFS mount for filesystem: sdb

sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK
driverbyte=DRIVER_SENSE,SUGGEST_OK

sd 11:0:0:1: [sdc] Sense Key : Data Protect [current] 

sd 11:0:0:1: [sdc] Add. Sense: Write protected
end_request: I/O error, dev sdc, sector 0
Filesystem "sdc": Disabling barriers, trial barrier write failed
XFS mounting filesystem sdc

sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK
driverbyte=DRIVER_SENSE,SUGGEST_OK

sd 11:0:0:1: [sdc] Sense Key : Data Protect [current] 

sd 11:0:0:1: [sdc] Add. Sense: Write protected
end_request: I/O error, dev sdc, sector 1953792056
xfs_force_shutdown(sdc,0x1) called from line 420 of file
fs/xfs/xfs_rw.c.  Return address = 0xffffffff80381f89

Filesystem "sdc": I/O Error Detected.  Shutting down filesystem: sdc

Please umount the filesystem, and rectify the problem(s)

I/O error in filesystem ("sdc") meta-data dev sdc block
0x74748038       ("xlog_bwrite") error 5 buf count 262144

XFS: failed to locate log tail
XFS: log mount/recovery failed: error 5
XFS: log mount failed

I don't really grasp what's wrong...

-- 
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Emmanuel Florac     |   Intellique
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Re: can't mount XFS from a read-only device

[Eric Sandeen]

Emmanuel Florac wrote:
> Hello all, 
> 
> I'm using a RAID enclosure that provides read-only snapshots. It works
> perfectly fine using JFS.
> But with XFS, I keep trying and it keeps failing :
> 
> XFS mounting filesystem sdb
> 
> Ending clean XFS mount for filesystem: sdb
> 
> sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK
> driverbyte=DRIVER_SENSE,SUGGEST_OK
> 
> sd 11:0:0:1: [sdc] Sense Key : Data Protect [current] 
> 
> sd 11:0:0:1: [sdc] Add. Sense: Write protected
> end_request: I/O error, dev sdc, sector 0
> Filesystem "sdc": Disabling barriers, trial barrier write failed
> XFS mounting filesystem sdc
> 
> sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK
> driverbyte=DRIVER_SENSE,SUGGEST_OK
> 
> sd 11:0:0:1: [sdc] Sense Key : Data Protect [current] 
> 
> sd 11:0:0:1: [sdc] Add. Sense: Write protected
> end_request: I/O error, dev sdc, sector 1953792056
> xfs_force_shutdown(sdc,0x1) called from line 420 of file
> fs/xfs/xfs_rw.c.  Return address = 0xffffffff80381f89
> 
> Filesystem "sdc": I/O Error Detected.  Shutting down filesystem: sdc
> 
> Please umount the filesystem, and rectify the problem(s)
> 
> I/O error in filesystem ("sdc") meta-data dev sdc block
> 0x74748038       ("xlog_bwrite") error 5 buf count 262144
> 
> XFS: failed to locate log tail
> XFS: log mount/recovery failed: error 5
> XFS: log mount failed
> 
> I don't really grasp what's wrong...
> 

try mount -o norecovery (and maybe -o nobarrier)

-Eric

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Re: can't mount XFS from a read-only device

[Emmanuel Florac]

Le Fri, 09 Oct 2009 13:59:13 -0500 vous écriviez:

> try mount -o norecovery (and maybe -o nobarrier)

Thank you, that worked.

I can't help but think that when given the "ro" option, XFS shouldn't
try to write a single bit to the underlying device, or else what's the
point?

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Emmanuel Florac               www.intellique.com   
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Re: can't mount XFS from a read-only device

[Eric Sandeen]

Emmanuel Florac wrote:
> Le Fri, 09 Oct 2009 13:59:13 -0500 vous écriviez:
> 
>> try mount -o norecovery (and maybe -o nobarrier)
> 
> Thank you, that worked.
> 
> I can't help but think that when given the "ro" option, XFS shouldn't
> try to write a single bit to the underlying device, or else what's the
> point?

For a dirty log, we do still recover -unless- the underlying device is
RO.  Otherwise you get a corrupt fs mounted ro.... other filesystems do
the same thing, FWIW.

For a clean log I agree; what kernel was this?  I vaguely remember a fix
in this area.

Which option solved it?  (norecovery I'm guessing)

-Eric

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Re: can't mount XFS from a read-only device

[Emmanuel Florac]

Le Fri, 09 Oct 2009 14:28:47 -0500 vous écriviez:

> For a clean log I agree; what kernel was this?  I vaguely remember a
> fix in this area.

It's a 2.6.24.7. I did a quick try with 2.6.27.25 and got exactly the
same error.

> Which option solved it?  (norecovery I'm guessing)

Yes, norecovery was the missing part.

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Emmanuel Florac               www.intellique.com   
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Re: can't mount XFS from a read-only device

[Emmanuel Florac]

Le Fri, 9 Oct 2009 19:43:51 +0200 vous écriviez:

> Log recovery is failing on a read-only device.  Try mounting
> with the "ro,norecovery" options.  However, this will give you a
> potentially inconsistent view of the filesystem.
> 
> Are you snapshotting a live filesystem?  If yes, then I'd suggest
> using xfs_freeze -f/snapshot/xfs_freeze -u to get consistent
> snapshots.

Yes, norecovery did it. I did snapshots previously using LVM, but these
are writable, so only "nouuid" is necessary (to mount the original FS
and snapshot side by side).

I thought that xfs_freeze was broken recently?

-- 
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Emmanuel Florac               www.intellique.com   
--------------------------------------------------

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