[lustre-discuss] Does lustre 2.10 client support 2.5 server ?

[Riccardo Veraldi]

I had a problems between 2.9.0 servers and 2.10.1 clients.
Actually from 2.10.1 clients I can list directories and files on my
Lustre FS OSTs, but I am not able to access any file for reading or writing.
I solved the problem decreasing the number of peer credits in ko2iblnd
to 8 instead of 128, client side.
This worked but I do not know exactly what is causing this problem.
these are the errors I was getting.

Nov 21 11:23:35 psana101 kernel: Lustre:
2287:0:(client.c:2114:ptlrpc_expire_one_request()) @@@ Request sent has
failed due to network error: [sent 1511292215/real 1511292215] 
req at ffff8801e8f08000 x1584330612541264/t0(0)
o3->ffb11-OST000e-osc-ffff8806320a3000 at 172.21.52.66@o2ib2:6/4 lens
608/432 e 0 to 1 dl 1511292227 ref 2 fl Rpc:eX/2/ffffffff rc 0/-1
Nov 21 11:23:35 psana101 kernel: Lustre:
2287:0:(client.c:2114:ptlrpc_expire_one_request()) Skipped 366 previous
similar messages
Nov 21 11:23:35 psana101 kernel: Lustre:
ffb11-OST000e-osc-ffff8806320a3000: Connection to ffb11-OST000e (at
172.21.52.66 at o2ib2) was lost; in progress operations using this service
will wait for recovery to complete



On 11/9/17 3:13 PM, Dilger, Andreas wrote:
> On Nov 9, 2017, at 05:27, Andrew Elwell <andrew.elwell at gmail.com> wrote:
>>> My Lustre server is running the version 2.5 and I want to use 2.10 client.
>>> Is this combination supported ? Is there anything that I need to be aware of
>> 2 of our storage appliances (sonnexion 1600 based) run 2.5.1, I've
>> mounted this OK on infiniband clients fine with 2.10.0 and 2.10.1 OK,
>> but a colleague has since had to downgrade some of our clients to
>> 2.9.0 on OPA / KNL hosts as we were seeing strange issues (can't
>> remember the ticket details)
> If people are having problems like this, it would be useful to know the
> details.  If you are using a non-Intel release, you should go through your
> support provider, since they know the most details about what patches are
> in their release.
>
>> We do see the warnings at startup:
>> Lustre: Server MGS version (2.5.1.0) is much older than client.
>> Consider upgrading server (2.10.0)
> This is a standard message if your client/server versions are more than 0.4 releases apart.  While Lustre clients and servers negotiate the supported features between them at connection time, so there should be broad interoperability between releases, we only test between the latest major releases (e.g. 2.5.x and 2.7.y, or 2.7.y and 2.10.z), it isn't possible to test interoperability between every release.
>
> Cheers, Andreas
> --
> Andreas Dilger
> Lustre Principal Architect
> Intel Corporation
>
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