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

[Peter Bortas]

Hi Andreas,

"Backing up" is easy enough. ZFS snapshots are nice and I'll make an
extra dump of the MDS.

The consensus seems to be that online upgrade should work but is
avoided in the field. So I'll skip working into that minefield this
time.

Thanks!
-- 
Peter Bortas, NSC


On Mon, Jul 11, 2016 at 12:53 AM, Dilger, Andreas
<andreas.dilger at intel.com> wrote:
> We typically test 2.x->2.x+1 upgrades, both live and offline, for every version of Lustre. That said, there are a large number of possible states that may occur with a running job, so it isn't possible to test everything. If you are ready to abort the long-running job, then trying the live upgrade and having to restart if it fails isn't any worse.
>
> I'd always recommend to make a backup of the MDT, regardless of whether you are doing an upgrade or not, since it is a lot easier to restore only the MDT if there are problems than to restore the whole filesystem.
>
> Cheers, Andreas
>
>> On Jul 8, 2016, at 09:08, Peter Bortas <bortas at gmail.com> wrote:
>>
>> 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
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