Dell Unity: How to Reboot a Storage Processor (User Correctable).

Rebooting a Storage Processor (SP) can safely resolve minor problems with the SP, its components, or the system software on the SP.

CAUTION 
When an SP reboots, it stops servicing I/O to hosts. In virtual deployments, data is unavailable during an SP reboot. In physical deployments, all NAS servers on the SP fail over to the other SP, if it is healthy. By default, when the SP has finished rebooting, the NAS servers fail back to it. If the Failback Policy is disabled, all NAS servers owned by the rebooting SP will not failback automatically. Once the SP is back online, NAS Servers will remain on the peer SP. Performance can be impacted when all NAS servers reside on a single SP. You can manually fail back the NAS servers when both SPs are online.

On Unisphere:

On SSH:

1. Issue the command: svc_shutdown --reboot spx , where spx is spa or spb, depending if the SP to be rebooted is SP A or SP B.
2. SP Boot can be monitored from the surviving SP with the following command: svc_diag --monitor-peer  
3. The following KB article can be followed for further information on how to monitor the SP boot sequence.