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Re: power failure causes files loss

To: adamantzj <tzj1983@xxxxxxx>
Subject: Re: power failure causes files loss
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Fri, 23 Apr 2010 15:40:47 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <28340118.post@xxxxxxxxxxxxxxx>
References: <28340118.post@xxxxxxxxxxxxxxx>
User-agent: Thunderbird 2.0.0.24 (Macintosh/20100228)
adamantzj wrote:
> 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? 

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

>      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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