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[SLUG] : Increasing filesystem reliability (was : Filesystem which allows online fsck?)


Erik de Castro Lopo wrote:

> Does anyone know of a Linux filesystem which allows online
> fsck on a disk that is currently mounted read/write?

Rather than asking for a filesystem, maybe I should be asking for
better use of the one we're currently using, Ext3.

The application is one when we're using real hard disks in an
envionment where we can expect the machines to lose power
unexpectedly (if that makes sense). In particular we can not
expect to always have a clean shutdown.

In the above situation we are seeing machines have difficulty
when coming up after a powerloss. I suspect that we end up with
problems that even Ext3's journalling isn't enough to cope with
and I suspect that its actually the loss of disk metadata which
is causing the problems.

With the above in mind, I've been looking at the mount options
for Ext3 and we are currently testing the following:

    dirsync - Sync directory metadata to disk.
    noatime - Updating atime results in a disk write and we're
              trying to reduce the number of non-essential disk
              writes.
    nodiratime - As above.

Another option I'm looking into is the possibility of running
the sync command at known idle times which follow a activity
which results in disk writes.

Does anyone have anything else to suggest?
  
Cheers,
Erik
-- 
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Erik de Castro Lopo
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"I have never met anyone who can do Scheme, Haskell, and C pointers
who can't pick up Java in two days, and create better Java code than
people with five years of experience in Java." --
http://www.joelonsoftware.com/articles/ThePerilsofJavaSchools.html