Tru64 UNIX versions prior to V5 do not utilise disk serial numbers or WWIDs, whereas V5’s support for multi-pathing requires unique disk serial number or WWIDs to correctly identify each discrete storage element.
Avanti provides for this in one of two ways:
1.By default, if the serial number field is blank, Avanti derives a serial number from the disk's configured controller bus and target. For example, disk0.0 produces SRL0000 and disk0.1 produces SRL0101. If that default is already in use in the same emulator process, Avanti uses a fallback that also includes the parent controller's PCI device number.
2.The user can enter a unique serial number in the serial number field of a disk's advanced properties using the Configuration Utility. The disk serial number can be any unique value. The special default for HSZ22 disks is described below.
Generated serial numbers are not written into the configuration file. They can therefore change if a disk moves to another bus, target, or controller. For a stable identity across configuration changes or migrations, set an explicit unique serial number before the guest begins using the disk.
Warning: Once a Tru64 UNIX configuration is built, do not modify the disk serial numbers. Doing so may cause Tru64 UNIX to think a disk has been changed out and invalidate the configuration.
The exception to the normal positional default is the HSZ disk type. When creating a custom disk size using the Avanti Configuration Utility, the disk type is assigned as HSZ22. An HSZ22 disk with a blank serial number receives the fixed value 00000002198505070c012c21bba00300 when that value is not already in use. A later blank disk that collides with a generated default receives the PCI-device fallback described above.
The following Tru64 UNIX array-query, WWID, migration, and patch-kit behavior is retained as historical field guidance. It has not been independently revalidated for Avanti 5.1.0. The structure of the special HSZ serial number was important to a small number of pre-V5 releases with certain patchkits when handling HSZ disks; for them at least one valid HSZ serial number/WWID had to be present for those releases to recognize the HSZ type. If the HSZ type is not needed, use one of the other types.
When using disk serial numbers or WWIDs with V5 releases, care must be taken when migrating an existing installation to ensure the donor's disk serial numbers are carried forward to the migrated installation. Under V5, the WWIDs can be viewed via:
# hwmgr -show scsi -full
…
SCSI DEVICE DEVICE DRIVER NUM DEVICE FIRST
HWID: DEVICEID HOSTNAME TYPE SUBTYPE OWNER PATH FILE VALID PATH
-------------------------------------------------------------------------
34: 2 mareth disk none 0 1 dsk1 [0/1/0]
WWID:04100038:"DEC HSZ22 00000002198505070c012c21bba00300"
…
SCSI DEVICE DEVICE DRIVER NUM DEVICE FIRST
HWID: DEVICEID HOSTNAME TYPE SUBTYPE OWNER PATH FILE VALID PATH
-------------------------------------------------------------------------
43: 9 mareth disk none 0 1 dsk8 [1/2/0]
WWID:0410001f:"DEC HSZ22 SRL0d02"
