[PLUG] LVM-induced hosage

[Russell Senior]

>>>>> "Russell" == Russell Senior <russell at personaltelco.net> writes:

Russell> # pvmove -v -i10 /dev/md4

Russell> And it commenced to, I presume, do the right thing.  After
Russell> about 17%, I got some messages (which regrettable I did not
Russell> preserve) about suspending (??) the pvmove, and my connection
Russell> to the machine froze (done remotely over the network, no
Russell> console available).  A few hours later, I got down to the
Russell> colo and looked at the console.  There was a login prompt,
Russell> which I could type at, but I never got a password prompt.
Russell> So, I rebooted and it came back up fine, but the pvmove had
Russell> clearly not succeeded.  Googling about, I found this, which
Russell> looks like what I saw:

Russell> http://www.novell.com/support/kb/doc.php?id=7004393
 
Russell> In brief, it suggests that you don't do a pvmove affecting a
Russell> logical volume that holds /var and/or /var/run.  Ouch, and:
Russell> WHY-IS-THIS-NOT-IN-A-MUCH-LARGER-FONT???

Galen> What distribution and what version of kernel and lvm?  Based on
Galen> my searches, I think it should be possible, but it looks like
Galen> there are multiple opportunities for deadlocks.

Galen> <http://sources.redhat.com/lvm2/wiki/FrequentlyAskedQuestions>

Russell> It's Gentoo.

Russell> # uname -a Linux iris 2.6.30.4 #3 SMP Mon Aug 10 09:22:09 PDT
Russell> 2009 i686 Genuine Intel(R) CPU @ 2.83GHz GenuineIntel
Russell> GNU/Linux

Russell> # pvmove --version LVM version: 2.02.73(2) (2010-09-18)
Russell> Library version: 1.02.54 (2010-08-18) Driver version: 4.14.0

Just to follow up, some combination of updating lvm2 to something more
recent:

root at iris russell # pvmove --version
  LVM version:     2.02.97(2) (2012-08-07)
  Library version: 1.02.76 (2012-08-07)
  Driver version:  4.14.0

and running pvmove on individual logical volumes allowed me to move
them off of the degraded physical volume with no further
freezes/deadlocks.  Yay!


-- 
Russell Senior, President
russell at personaltelco.net