[lustre-discuss] Is live upgrade of 2.4 to 2.5 unproblematic?

[Peter Bortas]

I'm upgrading a few ZFS backed filesystems from 2.4.2 to 2.5.3 (both
from the llnl chaos branch). Clients are already running 2.5EE. It's a
simple setup with no failover or mirroring of MDSs or OSSs. Originally
the plan was to do this with the filesystems unmounted on the clients,
but it looks like it will be hard to get a window to do that any time
soon.

Are there any known problems just doing an online upgrade 2.4 -> 2.5?

Is the recommended method still OSSs first and MDS last?

(Obviously the clients will lock up if they access these filesystems,
but locking them up for a fraction of a day beats aborting a 7 day
compute job.)

Regards,
-- 
Peter Bortas, NSC