[LU-13078] mgs trigger umount of clients Created: 13/Dec/19  Updated: 11/Sep/21

Status: Open
Project: Lustre
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: New Feature Priority: Minor
Reporter: Mahmoud Hanafi Assignee: Peter Jones
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Duplicate
duplicates LU-5703 Quiesce client mountpoints from the s... Open
Rank (Obsolete): 9223372036854775807

 Description   

It would a great feature for the MGS to ask/force a client to umount. This can be very useful in very large clusters with multiple networks.



 Comments   
Comment by Andreas Dilger [ 13/Dec/19 ]

This is similar to a feature which has been discussed in the past under the name of "Simplified Interoperability". In that feature the intent is to quiesce clients during a server failover or upgrade. There is already an architecture document for this feature, and surprisingly an old patch in the bugzilla 18496 ticket as well, though it is against Lustre 2.0 and would obviously need to be updated, but may at least serve as a guide for implementation.

Comment by Andreas Dilger [ 13/Dec/19 ]

One difference in this request vs. Simplified Interoperability is that unmounting a client may be problematic due to open file handles, unlike the original proposal which only quiescent the client mountpoints. The VFS will prevent the unmount with open files due to reference counting on the filesystem mountpoint. In newer kernels it may be possible to abort/evict the file handles from the filesystem side, but this would cause application errors.

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