[Dirvish] LVM2

Brian Martin Brian at MartinConsulting.com
Sun Feb 27 17:33:17 PST 2005


I've been using LVM2 on SUSE for quite some time, and been pretty satisfied.
Yes, you can do this on installation.  I don't recommend it for the root
partition, or boot if it's a separate partition, as it complicates various
kinds of recoveries.  For example, if you've hosed /etc/passwd or /etc/fstab
and want to fix it with Knoppix, Knoppix doesn't understand LVM2 yet so
won't let you get to those files.  

And yes, as said before, it works great with reiserfs.  I'm using this on my
back-up disks (i.e. the ones that hold the back-ups), with a logical volume
for each machine I'm backing up.  (There are business reasons for that that
probably aren't relevant to others.)  It's great to be able to resize
logical volumes on the fly.  

I typically allocate four partitions: boot, root, swap, LVM2.  Then all the
/var's and /usr's, and such live in the LVM2 space as logical volumes.

I first started using logical volumes (though not LVM2, of course) on AIX
with their JFS file system.  Life just gets a whole lot easier once you can
resize disks without having to move partition boundaries.  Reiser and most
other file systems make it even better, because you can both grow and shrink
filesystems while they're live.  AIX can only grow them -- shrinks require
you to allocate a new, smaller file system, move all the data over to it,
and delete the old one -- all assuming the files are not in use at the time.

If you haven't played with logical volumes of some sort, it's worth a couple
hours of head scratching to figure it out.

-Brian




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