[LU-14714] allow starting with only MGS config log if local llog write fails

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Affects Version/s: Lustre 2.15.0
• Assignee: Mikhail Pershin
• Reporter: Andreas Dilger

Description

It should be possible to mount an MDT or OST filesystem using only the MGS config llog if the local OSD filesystem is full. Currently the mount fails with -28 = -ENOSPC when it can't write a local copy of the config llog. This makes it impossible to mount the MDT/OST with Lustre and clean up space in a consistent manner without expert knowledge of the filesystem structure to do the cleanup when mounted as type ldiskfs.

mds02 kernel: LDISKFS-fs (dm-6): mounted filesystem with ordered data mode. Opts: user_xattr,errors=remount-ro,no_mbcache
,nodelalloc
mds02 kernel: LustreError: 5826:0:(osd_io.c:2172:osd_ldiskfs_write_record()) dm-6: error reading offset 0 (block 0, size 8192, offs 0), credits 29/29: rc = -28
mds02 kernel: LustreError: 5826:0:(llog.c:1419:llog_backup()) MGC10.10.1.17@o2ib: failed to backup log lfs1-MDT0001: rc = -28
mds02 kernel: LustreError: 5826:0:(mgc_request.c:1883:mgc_llog_local_copy()) MGC10.1.1.17@o2ib: failed to copy remote log lfs1-MDT0001: rc = -28
mds02 kernel: LustreError: 5989:0:(osp_sync.c:1524:osp_sync_init()) lfs1-OST0001-osc-MDT0001: can't initialize llog: rc = -28
mds02 kernel: LustreError: 5989:0:(obd_config.c:559:class_setup()) setup lfs1-OST0001-osc-MDT0001 failed (-28)
mds02 kernel: LustreError: 5989:0:(obd_config.c:1835:class_config_llog_handler()) MGC10.10.1.17@o2ib: cfg command failed: rc = -28
mds02 kernel: Lustre:    cmd=cf003 0:lfs1-OST0001-osc-MDT0001  1:lfs1-OST0001_UUID  2:10.10.1.19@o2ib  \x0a
mds02 kernel: LustreError: 15c-8: MGC10.10.1.17@o2ib: The configuration from log 'lfs1-MDT0001' failed (-28). This may be the result of communication errors between this node and the MGS, a bad configuration, or other errors. See the syslog for more information.

Issue Links

• is related to: LU-17184 remove corrupted local config llog