[LU-19916] start MGS replicas on MDTs/OSTs

• Type: Task
• Resolution: Unresolved
• Priority: Medium
• Severity: 3
• Assignee: WC Triage
• Reporter: Lai Siyao

Description

Start MGS replicas on MDTs/OSTs which are not located on the MGS0
primary and failover hosts. And once the target which the MGS
replica is running on is stopped, the MGS replica will be stopped
as well, and it will notify the ll_cfg_requeue thread to start
another MGS replica on other target if possible.

Register MGS replica as observer of MGC, so that it can be notified
when the config is changed.

Issue Links

• is related to: LU-17819 LMR1a: Replicate MGS Services to Multiple MDS
• is related to: LU-17818 LMR: Lustre Metadata Redundancy
• is related to: LU-19915 keep client configurations on MDTs/OSTs in sync with MGS0
• is related to: LU-19917 MGS replica imperative recovery support