On 2013/29/04 1:51 PM, "Ben Evans" <Ben.Evans(a)terascala.com> wrote:
Clients can maintain connections to multiple MGSes,
Right, this is fairly common.
but you can't connect to a 1.8 and a 2.x filesystem at the same
It's possible that this is the case, but a bit surprising since I'm not
of any reason why this wouldn't work. The state on the client should be
on a per-mountpoint basis. While we test 1.8 clients with 2.x servers, I
think we've ever done a test with mixed versions on one client at the same
[hpdd-discuss-bounces(a)lists.01.org] on behalf of John Richards
Sent: Monday, April 29, 2013 3:39 PM
To: Dilger, Andreas
Subject: Re: [HPDD-discuss] Upgrading 1.8.X -> 2.X
On Apr 29, 2013, at 11:15 , "Dilger, Andreas" <andreas.dilger(a)intel.com>
> On 2013-04-26, at 12:32, "John Richards"
>> Lustre fans,
>> We have four lustre filesystems in production, and are considering
>>running Lustre 2.X in the next year. I'd like a bit of advice on
>>upgrade paths, and I apologize if some of this has been covered before
>>- some of the details are eluding me. The main question is, can the
>>MGS be upgraded to 2.X on its own? If so, would it still support Lustre
>>1.8.3 OSSs and MDSs? Would a Lustre 2.X MGS be possible if all the
>>other systems were at Lustre 1.8.7 or better?
> It isn't possible to run different 1.8/2.x versions on the servers, and
>this includes the MGS. As it stands in 1.8 and 2.x MGS code it knows far
>too much about the internal details of how the servers are configured,
>yet the way this happens is somewhat specific to each version of Lustre.
>In 2.4 this has been improved somewhat, but I think some more separation
>is still needed.
> Probably the way you want to move forward is to split your single MGS
>into per-filesystem MGS (possibly running on the backup MDS), and then
>they can be upgraded together with their respective filesystems.
> Cheers, Andreas
Thanks for the suggestion - per filesystem MGSs would allow us to upgrade
individual filesystems without tackling them all at once.
Clients only maintain communication with a single MGS, correct? We
usually mount multiple Lustre filesystems on clients at the same time,
and we'd have to do some juggling to handle that. I remember someone
saying you could mount filesystems from different MGSs on the same
client, but would have to expect that the client would only receive
updates from the last MGS contacted. Or that could be an unstable
situation (one that we should avoid entirely) and we'd need to restrict
each client to a single filesystem (and MGS) at a time.
Even so, it is nice to have more options. I appreciate the help.
HPDD-discuss mailing list
Lustre Software Architect
Intel High Performance Data Division