9.5 HP P4800 G2 SAN Solution for Bladesystem Maintenance Guide (AX696-96151, September 2011)
IMPORTANT: Replace the SAS switches one at a time. When you remove a switch, I/O continues
on the remaining switch. Before resetting a switch, verify that all storage is accessible by the
remaining data path. Replacing both SAS switches at one time disconnects the storage and could
compromise data integrity.
If a SAS switch fails, storage access continues through the remaining SAS switch. This causes
storage access to set a preference to all LUNs in the remaining data path. This preference remains
in place until the controllers in the blade enclosure are power cycled, or the remaining path becomes
unavailable.
CAUTION: Power down the disk enclosure before disconnecting a SAS cable. Failing to do so
may damage the I/O module.
To replace the SAS switch:
1. Remove the power cable.
2. Disconnect the SAS cables, noting which cable goes to which port.
3. Remove the switch.
4. Install the replacement switch.
5. Attach the power cable.
6. Update the switch firmware.
a. Open the HP Virtual SAS Manager.
b. Select Force VSM Active.
This selection copies the zone and firmware information from the active switch to the passive,
replacement switch. The replacement switch then becomes the active switch.
7. Reconnect the SAS cables to their original locations, see “HP P4800 G2 solution cabling”
(page 31).
NOTE: Do not attach the SAS cables to the replacement switch until the firmware update is
complete.
Wait at least 60 seconds before removing another SAS switch.
The SAS switch should now provide a redundant access path to storage. Storage controllers will
distribute I/O evenly over the switches upon restart.
Replacing a SAS cable
CAUTION: Failing to follow these steps in this order may damage the I/O module.
1. Before disconnecting a SAS cable, power down the server blades using the procedures to
shut down the management group in the CMC Online Help or HP P4000 SAN Solution User
Guide.
2. Manually power off the disk enclosure.
3. Replace the SAS cable.
See “HP P4800 G2 solution cabling” (page 31) for an illustration of HP P4800 G2 solution
connectivity.
Replacing a SAS cable 25