[LU-12998] DNE3: tunable to disable directory creation on MDT

• Type: Improvement
• Resolution: Unresolved
• Priority: Major
• Fix Version/s: Lustre 2.16.0
• Affects Version/s: Lustre 2.14.0, Lustre 2.12.4
• Labels: medium
• Epic Link: MDT rebalance v3
• Assignee: Lai Siyao
• Reporter: Andreas Dilger

Description

In order to allow draining an MDT for removal from the filesystem, or to disable it temporarily, it makes sense to add an "mdt.*.no_create" parameter on the MDT similar to "obdfilter.*.no_precreate" on the OST, and a matching mount option "-o no_create". The OS_STATE_NOPRECREATE" flag should be set in obd_statfs from the MDT to let clients/MDS know that it should be skipped.

This should result in new stripes directories skipping the MDT during selection for "lfs mkdir -i -1", auto striping, etc.

Issue Links

• is cloned by: LU-17299 DNE3: disable new regular file creation on MDTs mounted with 'no_create'
• is related to: LU-17300 Avoid creating new dir/file/object on newly added MDT/OST
• is related to: LU-17334 Client should handle dir/file/object created on newly added MDT/OST
• is related to: LU-12025 Adding OST may cause EIO - delay activation of new OSTs on existing filesystem
• is related to: LU-16024 Allow permanently removing an MDT from config
• is related to: LU-7668 permanently remove deactivated OSTs from configuration log