[LU-7668] permanently remove deactivated OSTs from configuration log

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Assignee: Stephane Thiell
• Reporter: Andreas Dilger

Description

When an OST is permanently removed from the filesystem, the current process is to store a conf_param that marks the OSC permanently inactive in the configuration log, but it doesn't remove the actual OSC records from the config llog. That is needed for clients already mounting the filesystem so that they don't wait for the OST to be recovered, since only new records added to the end of config llog are processed by already-mounted clients.

However, for clients newly mounting the filesystem it may be desirable, if the OST is permanently deleted, to remove the OST record from the configuration log completely so that new client mounts don't even try to connect to it. This can be done relatively easily by cancelling the llog record(s) for the removed OST(s) so that the client doesn't process them at all.

The other area that may need fixing is lfs df, since it currently iterates over OST and MDT indices sequentially until it gets a -ENODEV return code that indicates no more OST/MDT devices are available. This will result in temporarily inactive OSTs to be printed, since the admin should know when there are offline OSTs, but it should not result in unconfigured OSTs being printed. It looks like -EAGAIN being returned from IOC_OBD_STATFS will result in the OST/MDT being silently skipped as we would want in this case. This needs to be verified.

It looks like lov_iocontrol() is returning -EAGAIN correctly, but lmv_iocontrol() is incorrectly returning -ENODATA for tgt == NULL instead of -EAGAIN, and not handling the OBD_STATFS_NODELAY flag in uarg at all.

Issue Links

• is blocked by: LU-15000 MDS crashes with (osp_dev.c:1404:osp_obd_connect()) ASSERTION( osp->opd_connects == 1 ) failed
• is related to: LU-7731 lctl dl - command don't report correct 'active' - state
• is related to: LU-14090 lctl replace_nids and starting target with local copy of logs
• is related to: LU-14403 lctl dl UP and lfs df problem with conf_param osc.active=0 after client remount
• is related to: LUDOC-352 document lctl llog_print
• is related to: LU-17299 DNE3: disable new regular file creation on MDTs mounted with 'no_create'
• is related to: LU-16475 Reusing OST indexes after lctl del_ost
• is related to: LU-12998 DNE3: tunable to disable directory creation on MDT
• is related to: LU-4295 removing files on deactivated OST doesn't free up space
• is related to: LU-4397 Permanently disabled OST causes clients to hang on df (statfs)
• is related to: LU-6601 deactivated OSTs do not appear to be inactive according to 'lctl dl'
• is related to: LU-16024 Allow permanently removing an MDT from config
• is related to: LU-6818 quiet permanently deactivated OSTs in "lfs df"
• is related to: LU-8920 don't print permanently deactivated OSTs in lfs df output