[LU-4243] multiple servicenodes or failnids: wrong client llog registration

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.6.0, Lustre 2.4.2, Lustre 2.5.1
• Affects Version/s: Lustre 2.4.1, Lustre 2.5.0
• Environment: failover MDS/MGS, failover OSTs
• Severity: 3
• Assignee: Hongchao Zhang
• Reporter: Erich Focht

Description

Since Lustre 2.4.0 we had problems with clients that could not connect after eg. the MGS was failing over. Most experiments we did with a client on the standby MGS server, the symptom was that the client only worked from the active MGS/MDS node, not from the passive one!

The reason for the problem seems to be commit d9d27cad and the following hunk of the patch:
@@ -1447,13 +1481,11 @@ static int mgs_write_log_failnids(const struct lu_env *env,
failnodeuuid, cliname);
rc = record_add_uuid(env, llh, nid, failnodeuuid);
}

• if (failnodeuuid) { + if (failnodeuuid) rc = record_add_conn(env, llh, cliname, failnodeuuid); - name_destroy(&failnodeuuid); - failnodeuuid = NULL; - }

  }

+ name_destroy(&failnodeuuid);
return rc;
}

This leads to a wrong lustre client llog when the lustre block devices are formated with multiple --servicenode options! Here is an example:

#09 (224)marker 6 (flags=0x01, v2.5.0.0) lnec-MDT0000 'add mdc' Mon Nov 11 17:03:21 2013-
#10 (080)add_uuid nid=10.3.0.34@o2ib(0x500000a030022) 0: 1:10.3.0.34@o2ib
#11 (128)attach 0:lnec-MDT0000-mdc 1:mdc 2:lnec-clilmv_UUID
#12 (136)setup 0:lnec-MDT0000-mdc 1:lnec-MDT0000_UUID 2:10.3.0.34@o2ib
#13 (080)add_uuid nid=10.3.0.34@o2ib(0x500000a030022) 0: 1:10.3.0.34@o2ib
#14 (104)add_conn 0:lnec-MDT0000-mdc 1:10.3.0.34@o2ib
#15 (080)add_uuid nid=10.3.0.35@o2ib(0x500000a030023) 0: 1:10.3.0.34@o2ib
#16 (104)add_conn 0:lnec-MDT0000-mdc 1:10.3.0.34@o2ib
#17 (160)modify_mdc_tgts add 0:lnec-clilmv 1:lnec-MDT0000_UUID 2:0 3:1 4:lnec-MDT0000-mdc_UUID
#18 (224)marker 6 (flags=0x02, v2.5.0.0) lnec-MDT0000 'add mdc' Mon Nov 11 17:03:21 2013-

The last add_uuid should have 1:10.3.0.35@o2ib instead of 1:10.3.0.34@o2ib.

And the reason is that only the first nid of the first --servicenode AKA --failnode entry is considered.

Please revert that little patch of mgs_llog.c.

Regards,
Erich

Issue Links

• is duplicated by: LU-4043 clients unable to reconnect after OST failover