[LU-5298] The lwp device cannot be started when we migrate from Lustre 2.1 to Lustre 2.4

Related — Fri, 1 Jul 2016 06:13:42 +0000

We have an issue with the quotas on our filesystems after the upgrade from
Lustre 2.1.6 to Lustre 2.4.3.

The quotas have been successfully enabled on all target devices using
'tunefs.lustre --quota $device'. The enforcement has been enabled with 'lctl conf_param scratch.quota.mdt=ug' and 'lctl conf_param scratch.quota.ost=ug' on
the MGS. However, the enforcement does not work and users can exceed their
quota limits.

Check of the quota_slave.info on the MDT:

# lctl get_param osd-*.*.quota_slave.info
osd-ldiskfs.scratch-MDT0000.quota_slave.info=
target name:    scratch-MDT0000
pool ID:        0
type:           md
quota enabled:  ug
conn to master: not setup yet
space acct:     ug
user uptodate:  glb[0],slv[0],reint[1]
group uptodate: glb[0],slv[0],reint[1]

We can see that the connection to the QMT is not setup yet. I also noticed that
the lwp device is not started, so no callback can be sent to the QMT.

By looking at the code, it seems that the lwp device cannot be started when we
migrate from Lustre 2.1 to Lustre 2.4.

In lustre/obdclass/obd_mount_server.c:

 717 /**
 718  * Retrieve MDT nids from the client log, then start the lwp device.
 719  * there are only two scenarios which would include mdt nid.
 720  * 1.
 721  * marker   5 (flags=0x01, v2.1.54.0) lustre-MDT0000  'add mdc' xxx-
 722  * add_uuid  nid=192.168.122.162@tcp(0x20000c0a87aa2)  0:  1:192.168.122.162@tcp
 723  * attach    0:lustre-MDT0000-mdc  1:mdc  2:lustre-clilmv_UUID
 724  * setup     0:lustre-MDT0000-mdc  1:lustre-MDT0000_UUID  2:192.168.122.162@tcp
 725  * add_uuid  nid=192.168.172.1@tcp(0x20000c0a8ac01)  0:  1:192.168.172.1@tcp
 726  * add_conn  0:lustre-MDT0000-mdc  1:192.168.172.1@tcp
 727  * modify_mdc_tgts add 0:lustre-clilmv  1:lustre-MDT0000_UUID xxxx
 728  * marker   5 (flags=0x02, v2.1.54.0) lustre-MDT0000  'add mdc' xxxx-
 729  * 2.
 730  * marker   7 (flags=0x01, v2.1.54.0) lustre-MDT0000  'add failnid' xxxx-
 731  * add_uuid  nid=192.168.122.2@tcp(0x20000c0a87a02)  0:  1:192.168.122.2@tcp
 732  * add_conn  0:lustre-MDT0000-mdc  1:192.168.122.2@tcp
 733  * marker   7 (flags=0x02, v2.1.54.0) lustre-MDT0000  'add failnid' xxxx-
 734  **/
 735 static int client_lwp_config_process(const struct lu_env *env,
 736                      struct llog_handle *handle,
 737                      struct llog_rec_hdr *rec, void *data)
 738 {
[...]
 779         /* Don't try to connect old MDT server without LWP support,
 780          * otherwise, the old MDT could regard this LWP client as
 781          * a normal client and save the export on disk for recovery.
 782          *
 783          * This usually happen when rolling upgrade. LU-3929 */
 784         if (marker->cm_vers < OBD_OCD_VERSION(2, 3, 60, 0))
 785             GOTO(out, rc = 0);

The function checks the MDT server version in the llog. I checked on the MGS of
our Lustre 2.4 filesystem and the version of the device scratch-MDT0000-mdc is
2.1.6.0.

#09 (224)marker   5 (flags=0x01, v2.1.6.0) scratch-MDT0000 'add mdc' Sat Jul  5 14:40:44 2014-
#10 (088)add_uuid  nid=192.168.122.41@tcp(0x20000c0a87a29)  0:  1:192.168.122.41@tcp
#11 (128)attach    0:scratch-MDT0000-mdc  1:mdc  2:scratch-clilmv_UUID
#12 (144)setup     0:scratch-MDT0000-mdc  1:scratch-MDT0000_UUID  2:192.168.122.41@tcp
#13 (168)modify_mdc_tgts add 0:scratch-clilmv  1:scratch-MDT0000_UUID  2:0  3:1  4:scratch-MDT0000-mdc_UUID
#14 (224)marker   5 (flags=0x02, v2.1.6.0) scratch-MDT0000 'add mdc' Sat Jul  5 14:40:44 2014-

After a writeconf on the filesystem, the llog has been updated and the device scratch-MDT0000-mdc is now registered with version 2.4.3.0.

#09 (224)marker   6 (flags=0x01, v2.4.3.0) scratch-MDT0000 'add mdc' Sat Jul  5 15:19:27 2014-
#10 (088)add_uuid  nid=192.168.122.41@tcp(0x20000c0a87a29)  0:  1:192.168.122.41@tcp
#11 (128)attach    0:scratch-MDT0000-mdc  1:mdc  2:scratch-clilmv_UUID
#12 (144)setup     0:scratch-MDT0000-mdc  1:scratch-MDT0000_UUID  2:192.168.122.41@tcp
#13 (168)modify_mdc_tgts add 0:scratch-clilmv  1:scratch-MDT0000_UUID  2:0  3:1  4:scratch-MDT0000-mdc_UUID
#14 (224)marker   6 (flags=0x02, v2.4.3.0) scratch-MDT0000 'add mdc' Sat Jul  5 15:19:27 2014-

Check of the quota_slave.info:

# lctl get_param osd-*.*.quota_slave.info
osd-ldiskfs.scratch-MDT0000.quota_slave.info=
target name:    scratch-MDT0000
pool ID:        0
type:           md
quota enabled:  none
conn to master: setup
space acct:     ug
user uptodate:  glb[0],slv[0],reint[0]
group uptodate: glb[0],slv[0],reint[0]
# lctl conf_param scratch.quota.mdt=ug
# lctl conf_param scratch.quota.ost=ug
# lctl get_param osd-*.*.quota_slave.info
osd-ldiskfs.scratch-MDT0000.quota_slave.info=
target name:    scratch-MDT0000
pool ID:        0
type:           md
quota enabled:  ug
conn to master: setup
space acct:     ug
user uptodate:  glb[1],slv[1],reint[0]
group uptodate: glb[1],slv[1],reint[0]

Same behavior is observed on OSTs.

It would be better to:

get the current version of the MDT server instead of the one recorded in the llog
or modify the operations manual to perform a writeconf while upgrading to a major release
or add a CWARN before lustre/obdclass/obd_mount_server.c:785 GOTO(out, rc = 0);

I think this issue can be related to ~~LU-5192~~.

Whamcloud Community JIRA

[LU-5298] The lwp device cannot be started when we migrate from Lustre 2.1 to Lustre 2.4