power failure causes files loss
Hello,
I’m writing data on a server in my company, but power cut suddenly. I
had to restart the machine, then I found that many files in the working directory had been lost. I made some tries with xfs_repair and it didn't repair my corrupted file.
What are the reasons caused this problem? I would like to know is what can I do to resolve this problem? Is XFS able to recover my file with its right content, at least a consistent content?
I'm running a 2.6.24 kernel with xfsprogs-3.1.1, and the operating
system is RedHat Enterprise Linux 5 Server (64-bit).
Do you know if this problem has often been encountered, there is a way
to proceed?
Thank you !
Adamant
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View this message in context: http://old.nabble.com/power-failure-causes-files-loss-tp28340118p28340118.html Sent from the Xfs - General mailing list archive at Nabble.com. _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs
Quoted 10 lines · adamantzj
Hello,
I’m writing data on a server in my company, but power cut suddenly. I
had to restart the machine, then I found that many files in the working directory had been lost. I made some tries withxfs_repairand it didn't repair my corrupted file.What are the reasons caused this problem? I would like to know is what can I do to resolve this problem? Is XFS able to recover my file with its right content, at least a consistent content?
Well, anything written via buffered IO but not synced could be lost, in general. This is true for any filesystem.
Also, depending on your storage, if barriers were not enabled on something with a volatile write cache, this can cause problems on a power loss. This would be the case on lvm on rhel5 for example (if you had write caches on your drives).
You didn't say if repair found any problems, or if the filesystem had trouble mounting post-loss, etc... this would be useful info.
But in general, unsynced buffered data -will- be lost on a power loss, for any fs.
-Eric
Quoted 10 lines
I'm running a 2.6.24 kernel with xfsprogs-3.1.1, and the operating
system is RedHat Enterprise Linux 5 Server (64-bit).Do you know if this problem has often been encountered, there is a way
to proceed?Thank you !
Adamant
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adamantzj put forth on 4/23/2010 6:28 AM:
Quoted 15 lines
Hello,
I’m writing data on a server in my company, but power cut suddenly. I
had to restart the machine, then I found that many files in the working directory had been lost. I made some tries withxfs_repairand it didn't repair my corrupted file.What are the reasons caused this problem? I would like to know is what can I do to resolve this problem? Is XFS able to recover my file with its right content, at least a consistent content?
I'm running a 2.6.24 kernel with xfsprogs-3.1.1, and the operating
system is RedHat Enterprise Linux 5 Server (64-bit).
Quoted 6 lines
Do you know if this problem has often been encountered, there is a way
to proceed?Thank you !
Adamant
XFS isn't the cause of your problem. Running without a proper UPS is the cause of your problem. Fix the cause of your problem by purchasing a properly sized and instrumented/monitored UPS. YOU CANNOT rely on your OS or filesystem driver to prevent data loss due to power loss, or to properly recover from such unexpected power loss if/when it occurs. This is why you absolutely need to eliminate the possibility of unexpected power loss. This is the sole purpose for the existence of companies such as APC, Liebert, TrippLite and others.
I'd have thought by 2010 that the entire IT cadre worldwide would already be educated on proper power backup planning and procedures. I guess not.
Acquire a proper UPS and configure it properly, specifically meaning monitoring and alerts which will allow for performing a proper shutdown during an extended outage, and your problems will disappear.
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Stan _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs
Quoted 31 lines · On Saturday 24 April 2010, 00:25:41 Stan Hoeppner wrote:
adamantzj put forth on 4/23/2010 6:28 AM:
Quoted 14 lines
Hello,
I’m writing data on a server in my company, but power cut
suddenly. I had to restart the machine, then I found that many files in the working directory had been lost. I made some tries withxfs_repairand it didn't repair my corrupted file.What are the reasons caused this problem? I would like to know is what can I do to resolve this problem? Is XFS able to recover my file with its right content, at least a consistent content?
I'm running a 2.6.24 kernel with xfsprogs-3.1.1, and the operating
system is RedHat Enterprise Linux 5 Server (64-bit).Quoted 6 lines
Do you know if this problem has often been encountered, there is a
way to proceed?Thank you !
Adamant
XFS isn't the cause of your problem. Running without a proper UPS is the cause of your problem. Fix the cause of your problem by purchasing a properly sized and instrumented/monitored UPS. YOU CANNOT rely on your OS or filesystem driver to prevent data loss due to power loss, or to properly recover from such unexpected power loss if/when it occurs. This is why you absolutely need to eliminate the possibility of unexpected power loss. This is the sole purpose for the existence of companies such as APC, Liebert, TrippLite and others.
Quoted 6 lines
I'd have thought by 2010 that the entire IT cadre worldwide would already be educated on proper power backup planning and procedures. I guess not.
Acquire a proper UPS and configure it properly, specifically meaning monitoring and alerts which will allow for performing a proper shutdown during an extended outage, and your problems will disappear.
While you're right for the general case of course, there are many other failure conditions, that an UPS will not prevent, eg. kernel crashes. Therefore there is an vivid interest, that any storage based filesystems should stay consistent _any_ time (and usually filesystem developers spend an considerable amount of their time on fixing such problems, if they arise).
Adamant, the people reading here are rarely trained in telepathic capabilities. If you need more specific answers, you need to provide more specific details, eg. mount options, error logs, etc.
Pete
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Quoted 45 lines · Hans-Peter Jansen
Quoted 30 lines · On Saturday 24 April 2010, 00:25:41 Stan Hoeppner wrote:
adamantzj put forth on 4/23/2010 6:28 AM:
Quoted 14 lines
Hello,
I’m writing data on a server in my company, but power cut
suddenly. I had to restart the machine, then I found that many files in the working directory had been lost. I made some tries withxfs_repairand it didn't repair my corrupted file.What are the reasons caused this problem? I would like to know is what can I do to resolve this problem? Is XFS able to recover my file with its right content, at least a consistent content?
I'm running a 2.6.24 kernel with xfsprogs-3.1.1, and the operating
system is RedHat Enterprise Linux 5 Server (64-bit).Quoted 6 lines
Do you know if this problem has often been encountered, there is a
way to proceed?Thank you !
Adamant
XFS isn't the cause of your problem. Running without a proper UPS is the cause of your problem. Fix the cause of your problem by purchasing a properly sized and instrumented/monitored UPS. YOU CANNOT rely on your OS or filesystem driver to prevent data loss due to power loss, or to properly recover from such unexpected power loss if/when it occurs. This is why you absolutely need to eliminate the possibility of unexpected power loss. This is the sole purpose for the existence of companies such as APC, Liebert, TrippLite and others.
Quoted 6 lines
I'd have thought by 2010 that the entire IT cadre worldwide would already be educated on proper power backup planning and procedures. I guess not.
Acquire a proper UPS and configure it properly, specifically meaning monitoring and alerts which will allow for performing a proper shutdown during an extended outage, and your problems will disappear.
While you're right for the general case of course, there are many other failure conditions, that an UPS will not prevent, eg. kernel crashes. Therefore there is an vivid interest, that any storage based filesystems should stay consistent _any_ time (and usually filesystem developers spend an considerable amount of their time on fixing such problems, if they arise).
Quoted 5 lines
Adamant, the people reading here are rarely trained in telepathic capabilities. If you need more specific answers, you need to provide more specific details, eg. mount options, error logs, etc.
Pete
See also:
"Eat My Data: How Everybody Gets File IO Wrong"
http://www.flamingspork.com/talks/
:)
-Eric
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Le Sat, 24 Apr 2010 19:05:43 +0200 vous écriviez:
Quoted 2 lines
that any storage based filesystems
should stay consistent _any_ time
AFAIK only FreeBSD UFS-with soft-updates actually comes close to that, at the huge cost of being impossibly complex :)
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Quoted 8 lines
While you're right for the general case of course, there are many other failure conditions, that an UPS will not prevent, eg. kernel crashes.
Therefore there is an vivid interest, that any storage based filesystems should stay consistent _any_ time (and usually filesystem developers spend an considerable amount of their time on fixing such problems, if they arise).
That's strictly speaking impossible, almost always undesirable, and at the same time easy to achieve: if you want something like that just mount with '-o sync' :-).
If you want that *and* excellent performance, just mount with '-o ponies' instead :-).
If you want that *and* excellent performance *and* scalable performance with small IO just mount with '-o unicorns' :-).
This topic has been already discussed a few times over in this mailing list, and in the kernel mailing etc.; those who can get it have gotten it, those who don't continue to whine.
The real problem is not so much the '-o ponies' (or '-o unicorns') attitude, it is that even those who get it still have a hard time with doing the right things because of limited or broken behaviour, at all levels (from the POSIX semantics of 'fsync' to the Linux page cache to the firmware of many drives).
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