Hardware RAID Level & Performance

[Henrique de Moraes Holschuh]

On Wed, 16 Feb 2005, Norman Zhang wrote:
> I'm not sure how's XFS compared to other fs. I've been using it for few 
> years. It seems to be fine.

It works fast as all heck, but your data will *NOT* necessarily survive a
crash (zeros everywhere if the data was not on disk).  The filesystem
metadata will survive the crash just fine, so you might not even know where
the corruption is.

So do not use it where you can reasonably expect a crash to happen, if the
data in it ain't transient.  IMHO, anyway.  That does mean do not run it in
a machine without SECDED memory or Chipkill memory (i.e. run it only where
you have working ECC single-bit correction in hardware, or something
better).

Every so often (like once an year) I'd run a xfs_repair on it, just in case
a kernel bug or memory corruption is silently screwing things up (if it gets
bad enough for XFS to notice it, it will *dead lock* that filesystem, and
hang everything that touches it).  It has happened to me in the past, but
that was more than one year ago, in Linux, and XFS has come a long way since
then.

All that said, I quite like XFS, and I use it a lot *except* on the root
filesystem (which is always ext3).  So far, nothing that uses fsync()
properly ever lost a single byte, and that covers the MTAs and Cyrus.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
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