[LU-10360] use Imperative Recovery logs for client->MDT/OST connections

• Type: New Feature
• Resolution: Unresolved
• Priority: Minor
• Assignee: Mikhail Pershin
• Reporter: Andreas Dilger

Description

The Imperative Recovery (IR) feature landed in LU-19 created a dynamic list of active server NIDs on the MGS for purposes of speeding up client recovery when a target failed over to another server node. A server failure triggered a notification from the MGS to the client to update its target NIDs to reconnect to the recovered server more quickly.

It would be possible to extend this mechanism to also use the MGS IR log to do initial client mount, so that the MGS did not need to store the OST/MDT NIDs statically in the config log, but rather get the current NIDs directly from the dynamic MGS log. This would facilitate Lustre running in configurations where the server NIDs are not static (e.g. cloud, DHCP, etc). The initial connection to the MGS node(s) can already be done using the MGS hostname, since mount.lustre will do DNS name resolution.

Some care would be needed when OSTs are being registered with the MGS, especially in testing environments where OSTs are reformatted regularly and often use the same fsname, since this may allow OSTs to register with the MGS that do not actually belong to the same filesystem.

Issue Links

• is duplicated by: LU-18164 MGS should dynamically track server NIDs
• is related to: LU-14090 lctl replace_nids and starting target with local copy of logs
• is related to: LU-18417 Finish IPv6 support
• is related to: LU-10359 remove NIDs from config llogs
• is related to: LU-16086 add generic LNet network number support
• is related to: LU-16722 MGS config log restructuring
• is related to: LU-18819 allow direct IB GUID addressing without IPoIB
• is related to: LU-18975 Nodemap-specific tunable parameter configuration
• is related to: LU-13306 allow clients to accept mgs_nidtbl_entry with IPv6 NIDs
• is related to: LU-18280 Advertise dynamically configured server NIDs to MGS
• is related to: LU-19229 improved IR NID list handling on client side
• is related to: LU-11077 Client-specific tunable parameter configuration
• is related to: LU-13340 add LCFG_ADD_UUIDv6 and related commands
• is related to: LU-14668 LNet: do discovery in the background
• is related to: LU-14608 Adding second network to filesystem
• is related to: LU-17906 conf-sanity test_153a: check mount failed
• is related to: LU-18799 mount fails with maximum NIDs in parameters
• is related to: LU-18815 proceed gracefully with more than 32 NIDs configured on server
• is related to: LU-19 imperative recovery
• is related to: LU-10391 LNET: Support IPv6
• is related to: LU-18885 manage large NID tables on MGS with multiple networks
• is related to: LU-18986 Target registration to handle large amount of NIDs
• is related to: LU-19095 Target notifies MGS about LNet changes
• is related to: LU-19253 fetch NIDs from LNet all at once
• is related to: LU-5881 Allow hostnames in NID
• is related to: LU-14714 allow starting with only MGS config log if local llog write fails
• is related to: LU-18587 allow more NIDs in mkfs.lustre / tunefs.lustre / mount.lustre params
• links to: RED-1552 depends on LU-10360