Dealing with SSWS

Replication and Disaster Recovery Administration Guide for Hitachi NAS Platform

Part Number

If production SDs are lost, recovery of the data on the backup SDs can leave them as S-Vols and put the mirror relationship into a state called SSWS. Uniquely, SSWS causes the S-Vols to become writable. But the server is unable to detect this state, and treats the S-Vols as secondary SDs in the usual way, refusing to perform I/O to them.

For the duration of the SSWS state, use the sd-peg command to override the SDs' normally-determined roles and make the NAS server treat S-Vols as primary SDs. Be sure to remove the peg using the sd-peg --default-role command as soon as the SSWS state ends. In all states not involving SSWS, the server must be allowed to detect SDs' mirror roles for itself.