[LU-12722] exclude local client mounted on MDS/OSS from recovery

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.14.0
• Assignee: Alex Zhuravlev
• Reporter: Alex Zhuravlev

Description

In order to mount a client locally on the OSS or MDS without affecting the recovery of local targets, we need the ability to mount without inserting the client into the last_rcvd file. That avoids the problem when a client+server crashes and the local client UUID is no longer available for the recovery, causing recovery to always take the maximum time.

Any modifying RPCs to the local OST should be synchronous by default, or possibly use commit-on-share, so that they do not need to be replayed if the server restarts. This implies that it is more desirable to schedule lfs mirror resync in such a way that it is reading from the local OSS and writing to a remote OSS. It might be desirable to allow this functionality to be disabled for testing purposes (e.g. local client mount in test scripts), or if local performance is more important than waiting for recovery to time out.

It should be possible to enable this mode automatically at mount time based on the client NID, rather than having e.g. a mount option force a "local mount", since it would only apply to targets that are on the same OSS/MDS and not remote targets

Issue Links

• is related to: LU-13379 interop b2_12/master: lustre-initialization failed: Unrecognized mount option "localrecov"
• is related to: LU-10191 FLR2: Server Local Client (SLC)
• is related to: LU-10158 FLR: Define a replica choosing policy function
• is related to: LU-2605 reduce the failover time when the MDS and OSS are on the same machine in High Availability