PRIMECLUSTER Global File Services Configuration and Administration Guide 4.1 (Linux)

3.1.1 Automatic recovery for primary MDS failures

There is one case in which the standby secondary MDS becomes the primary MDS to continue operation. This case occurs if both the primary and secondary MDSs are set up as operable and the primary MDS process fails. In this case, the following process is performed:

1) Switching the secondary MDS to the primary MDS

The secondary MDS operates as the primary MDS in place of the primary MDS that has failed.

In a file system in which three or more MDS nodes are set, if the secondary MDS does not work as the primary MDS after the specified time, a primary MDS can be activated from another MDS node to continue operations.

2) Replaying the update log

The new primary MDS replays the update log to ensure consistency of the file system.

3) Resuming processing after MDS switching

The AC sends a processing request to the new primary MDS. Until that request is accepted, all access to the file system is blocked.

4) Restarting the failed MDS

Usually, the MDS is restarted as the secondary MDS.

In a file system in which three or more MDS nodes are set, if the secondary MDS does not work after the specified time, a secondary MDS can be activated from another MDS node to continue operations.