On 2013/29/04 1:51 PM, "Ben Evans" <Ben.Evans(a)terascala.com&gt; 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 time IIRC. It's possible that this is the case, but a bit surprising since I'm not aware of any reason why this wouldn't work. The state on the client should be kept on a per-mountpoint basis. While we test 1.8 clients with 2.x servers, I don't think we've ever done a test with mixed versions on one client at the same time. Cheers, Andreas > ________________________________________ > From: hpdd-discuss-bounces(a)lists.01.org > [hpdd-discuss-bounces(a)lists.01.org] on behalf of John Richards > [john.richards(a)icecube.wisc.edu] > Sent: Monday, April 29, 2013 3:39 PM > To: Dilger, Andreas > Cc: hpdd-discuss(a)lists.01.org > Subject: Re: [HPDD-discuss] Upgrading 1.8.X -> 2.X > > On Apr 29, 2013, at 11:15 , "Dilger, Andreas" <andreas.dilger(a)intel.com&gt; > wrote: > >> On 2013-04-26, at 12:32, "John Richards" >> <john.richards(a)icecube.wisc.edu&gt; wrote: >> >>> 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 > > 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. > > John > john.richards(a)icecube.wisc.edu > > _______________________________________________ > HPDD-discuss mailing list > HPDD-discuss(a)lists.01.org > https://lists.01.org/mailman/listinfo/hpdd-discuss > > > Cheers, Andreas -- Andreas Dilger Lustre Software Architect Intel High Performance Data Division