[lustre-discuss] lustre client 2.9 cannot mount 2.10.0 OSTs

[Riccardo Veraldi]

Hello,

I have a new Lustre cluster based on Lustre 2.10.0/ZFS 0.7.0 on Centos 7.3
Lustre FS creation went smooth.
When I tryed then to mount from the clients, Lustre is not able to mount
any of the OSTs.
It stops at MGS/MDT level.

this is from the client side:

mount.lustre: mount 192.168..48.254 at tcp2:/scratch12 at
/reg/data/scratch12 failed: Invalid argument
This may have multiple causes.
Is 'scratch12' the correct filesystem name?
Are the mount options correct?
Check the syslog for more info.

Aug  7 17:58:53 psana1510 kernel: [285130.463377] LustreError:
29240:0:(mgc_request.c:335:config_log_add()) logname scratch12-client is
too long
Aug  7 17:58:53 psana1510 kernel: [285130.463772] Lustre:
3333:0:(client.c:2114:ptlrpc_expire_one_request()) @@@ Request sent has
failed due to network error: [sent 1502153933/real 1502153933] 
req at ffff88203d75ec00 x1574823717093632/t0(0)
o250->MGC192.168.48.254 at tcp2@192.168.48.254 at tcp2:26/25 lens 520/544 e 0
to 1 dl 1502153938 ref 1 fl Rpc:eXN/0/ffffffff rc 0/-1
Aug  7 17:58:53 psana1510 kernel: [285130.469156] LustreError: 15b-f:
MGC192.168.48.254 at tcp2: The configuration from log
'scratch12-client'failed from the MGS (-22).  Make sure this client and
the MGS are running compatible versions of Lustre.
Aug  7 17:58:53 psana1510 kernel: [285130.472072] Lustre: Unmounted
scratch12-client
Aug  7 17:58:53 psana1510 kernel: [285130.473827] LustreError:
29240:0:(obd_mount.c:1505:lustre_fill_super()) Unable to mount  (-22)

from the MDS side there is nothing in syslog. So I tried to engage tcpdump:

17:58:53.745610 IP psana1510.pcdsn.1023 >
psanamds12.pcdsn.cyborg-systems: Flags [S], seq 1356843681, win 29200,
options [mss 1460,sackOK,TS val 284847388 ecr 0,nop,wscale 7], length 0
17:58:53.745644 IP psanamds12.pcdsn.cyborg-systems >
psana1510.pcdsn.1023: Flags [R.], seq 0, ack 1356843682, win 0, length 0
17:58:58.757421 ARP, Request who-has psanamds12.pcdsn tell
psana1510.pcdsn, length 46
17:58:58.757441 ARP, Reply psanamds12.pcdsn is-at 00:1a:4a:16:01:56 (oui
Unknown), length 28

OSS, nothing in the log file or in tcpdump

lustre client is 2.9 and the server 2.10.0

I have no firewall running and no SElinux

this never happened to me before. I am usually running older lustre
versions on clients but I never had this problem before.
Any hint ?

thank you very much

Rick