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

Cloners — Mon, 8 Jan 2024 20:57:51 +0000

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.

Whamcloud Community JIRA

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