choosing a file system

[Janne Peltonen]

On Wed, Dec 31, 2008 at 07:38:21AM -0500, Adam Tauno Williams wrote:
> In regards to ext3 I'd pay attention to the vintage of problem reports
> and performance issues;  ext3 of several years ago is not the ext3 of
> today, many improvements have been made.  "data=writeback" mode can help
> performance quite a bit, as well as enabling "dir_index" if it isn't
> already (did it ever become the default?).  The periodic fsck can also
> be disabled via tune2fs.   I only point this out since, if you already
> have any ext3 setup,  trying the above are all painless and might buy
> you something.

I wouldn't call data=writeback painless. I had it on in the testing phase
of our current Cyrus installation, and if the filesystem had to be
forcibly unmounted by any reason (yes, there are reasons), the amount of
corruption in those files that happened to be active during the unmount
- well, it wasn't a nice sight. And the files weren't recoverable,
except from backup.

I never really got the point of the data=writeback mode. Sure, it
increases throughput, but so does disabling the journal completely, and
seems to me the end result as concerns data integrity is exactly the
same.


--Janne
-- 
Janne Peltonen <janne.peltonen at helsinki.fi> PGP Key ID: 0x9CFAC88B
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