On Wed, 2008-12-31 at 15:46 +0200, Janne Peltonen wrote: > 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. The *filesystem* is recoverable as the meta-data is journaled. *Contents* of files may be lost/corrupted. I'm fine with that since a serious abend usually leaves the state of the data in a questionable state anyway for reasons other than the filesystem; I want something I can safely (and quickly) remount and investigate/restore. It is a trade-off. ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
