[LU-3458] OST not able to register at MGS with predefined index.

• Type: Bug
• Resolution: Unresolved
• Priority: Critical
• Affects Version/s: Lustre 2.0.0, Lustre 2.1.0, Lustre 2.2.0, Lustre 2.3.0, Lustre 2.4.0, Lustre 1.8.x (1.8.0 - 1.8.5), Lustre 2.5.0
• Environment: Any lustre from 1.6.0 with mountconf and OST prepared with --index option.
• Severity: 3
• Assignee: WC Triage
• Reporter: Alexey Lyashkov

Description

client may have lost a reply to register target operation, but MGS will think reply is delivered and mark a target as used, but client don't have an reply accepted and think it need restart register from beginning after reconnect.
OOPS.
MGS send response a index already used.

[ 2619.730706] Lustre: MGC172.18.1.2@tcp: Reactivating import
[ 2626.816706] Lustre: 56551:0:(client.c:1819:ptlrpc_expire_one_request()) @@@ Request  sent has timed out for slow reply: [sent 1370729827/real 1370729827]  req@ffff8806014d5c00 x1437314393833474/t0(0) o253->MGC172.18.1.2@tcp@172.18.1.2@tcp:26/25 lens 4736/4736 e 0 to 1 dl 1370729834 ref 2 fl Rpc:X/0/ffffffff rc 0/-1
[ 2626.844904] LustreError: 166-1: MGC172.18.1.2@tcp: Connection to MGS (at 172.18.1.2@tcp) was lost; in progress operations using this service will fail
[ 2626.896533] Lustre: MGC172.18.1.2@tcp: Reactivating import
[ 2626.902111] Lustre: MGC172.18.1.2@tcp: Connection restored to MGS (at 172.18.1.2@tcp)
[ 2629.380926] Lustre: MGC172.18.1.2@tcp: Reactivating import
[ 2632.367220] LustreError: 15f-b: Communication to the MGS return error -98. Is the MGS running?
[ 2632.376077] LustreError: 58337:0:(obd_mount.c:1834:server_fill_super()) Unable to start targets: -98

attached logs describe that bug in details (log1 from MGS side, log2 from OSS side - initial register xid is x1437620344193026).

Bug hit because MGS don't schedule a reply to the target register command, and assume client always get a reply. Bug originally hit on Xyratex b_neo_stable branch (mostly 2.1 codebase) but quick look say - bug exist at 2.4 also.

Issue Links

• is related to: LU-16475 Reusing OST indexes after lctl del_ost
• is related to: LU-17716 add 'tunefs.lustre --replace' to allow OST to be skip MGS registration
• is related to: LU-14 live replacement of OST