HP StorageWorks MSA 2.8 SAN Switch - Manual (Page 77)

Firmware Download
77 Fabric OS Procedures Version 3.1.x/4.1.x User Guide
Non-Disruptive Firmware Activation
The v4.1 Fabric OS provides the ability to activate firmware non-disruptively.
The Core Switch 2/64 platform provides non-disruptive behavior as long as both
CP blades are installed, and that they are fully synchronized. Use the
haShow
command to confirm synchronization.
On Core Switch 2/64 with only 1 CP
Single CP Core Switch 2/64 system will need to reboot itself to activate firmware.
The process will be disruptive. Identical to the version 4.0.2 single CP firmware
activation.
On the SAN Switch 2/32 or other single-processor systems
Firmware “Fails-Over” to itself. However, the process takes longer as a reboot of
the operating system is required.