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 a serial number field is left blank in the Avanti configuration file, a unique serial number is generated for the disk using the format SRL00.

2.The user can enter a unique serial number in the serial number field of a disk's advanced properties using the Configuration Utility. Disk serial number can by any unique value except in the case of HSZ22 disks. More on HSZ disks below.

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 above rule is the HSZ disk type. When creating a custom disk size using the Avanti Configuration Utility, the disk type is assigned as HSZ22. If the disk serial number is left blank in the configuration file, Avanti assigns a fixed, valid, HSZ serial number to the first HSZ disk in the configuration: 00000002198505070c012c21bba00300. All subsequent HSZ disks with empty serial number fields are assigned the normal positional serial numbers ‘SRLx0y’ as above.

The structure of this special HSZ serial number is 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 must be present for those releases to recognize the HSZ type. However, 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"