Procedure To Set Uuid; Host Mode Setting - HP StorageWorks XP10000 - Disk Array Configuration Manual

The following host group mode (option) is available for OpenVMS:
Table 2 Host mode setting
Host Mode
33

Procedure to set UUID

HP recommends OpenVMS customers use Host Mode Option 33 to enable the UUID feature. This
increases the capabilities for OpenVMS hosts that access the XP disk array, by (1) allowing CU:LDEVs
above 7F:FF to be presented to the OpenVMS hosts and (2) allowing the OpenVMS system adminstrator
to define the DGA device number to present to the OpenVMS host.
If use of Host Mode Option 33 is enabled after devices were already presented to an OpenVMS
host, HP recommends rebooting the OpenVMS host. Though SYSMAN IO AUTO can be used to
discover new DGA devices, this helps avoid problems with stale data structures within OpenVMS.
SAN boot and UUID with OpenVMS. The UUID can be used with OpenVMS for Integrity servers. This
includes the system disk, quorum disk, and Dump Off System Disk (DOSD) volumes. However for
OpenVMS AlphaServer hosts, the UUID for those volumes must be set to the decimal value of the
hexidecimal value of the CU:LDEV value. If the CU:LDEV value is 01:FF, then the UUID must be set to
511 (the decimal value of 01FF). Thuse, none of these volumes can have a CU:LDEV value greater
than 7F:FF. Additionally, these volumes must use LUN numbers 1 to 255. These are limitations of the
AlphaServer firmware used (both for the definition of known paths by the wwidmgr and by the boot
code).
If Host Mode Option 33 is not set, then the default behavior is to present the volumes to the OpenVMS
host by calculating the decimal value of the hexadecimal CU:LDEV value. That calculated value will
be the value of the DGA device number.
CAUTION:
The UUID (or by default the decimal value of the CU:LDEV value) must be unique across the SAN
for the OpenVMS host and/or OpenVMS cluster. No other SAN storage controllers should present
the same value. If this value is not unique, data loss will occur.
If Host Mode Option 33 is not set, none of the OpenVMS LUNs can have a CU:LDEV value
greater than 7F:FF. That hexadecimal value equals decimal 32767, which is the largest DGA
device number allowed by OpenVMS.
If Host Mode Option 33 is set and the UUID for the LUN is not set, then the device will NOT be
presented to the OpenVMS host. If configuration problems arise, use the SYS$ETC:FIBRE_SCAN
program to search for devices that are presented to the OpenVMS host.
Use the following procedure to set the UUID.
12 Installing and configuring OpenVMS for the XP disk array
Description
Use this host mode to enable the option that sets the UUID