Data recovery and XFS (was: Re: [NCLUG] XFS, "Can't read superblock")

[Bob Proulx]

Sean Reifschneider wrote:
> ... That's the last XFS system I have right now, I've
> switched entirely back to ext3.
> 
> I know some people love XFS, but I don't like it.

I am one of those people who really like xfs.  However I admit that I
am also switching back to ext3.  There are couple of reasons for this
that have nothing to do with the ones you listed.

For one ext3 has had serious improvement over the last decade.  It has
risen up to be not far behind the filesystem leaders.  So moving back
to ext3 today is not like it was way back when.  The performance
difference is not as marked now.

But the real reason for me is that ext3 can both grow and shrink a
filesystem.  Deploying ext3 on lvm on raid means that I can reallocate
disk space as needed among partitions.  For my setup this only works
if I can steal space from the other partitions for the one I want to
grow.  Since xfs does not shrink, it only allows growth, I can't use
it like that.  I could only add additional disks and would not be able
to reallocate existing ones.  Therefore I have left xfs behind with a
tear in my eye.  I am back to using ext3 on lvm over raid and it is a
solid performer.

I could use reiserfs which also supports growing and shrinking.  I
have had really good luck with reiserfs and it performs very well in
all of my benchments.  But it also has some very serious issues for
the unwary.  For one if you have a reiserfs image on a reiserfs
filesystem then the fsck will be confused and pretty much destroy the
system.  It simply scans the disk looking for signatures indicating
the start of data and apparently does not distinguish between data and
metadata.  It apparently cross stitches these two filesystems together
trying to fsck and recover and the system really gets unhappy at that
point.  The moral here is never store a reiserfs image on a resierfs
filesystem.  One of my friends at work hit this case.  I have learned
never to mention reiserfs within his earshot or I end up listening to
long rants about it.

Bob