Tru64 UNIX V5 Disk Serial Number Issue
Older versions of Tru64 UNIX do not care about disk serial numbers. Tru64 UNIX V5 does care. V5 wants unique serial numbers for each disk.
Avanti deals with this issue in 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 SRL0<hex-pci-id>0<hex-scsi-id>.
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.
NOTE: 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 HSZ disks. HSZ disks require a specially formatted serial number. Furthermore, HSZ disk uniqueness is further defined by the disk size. Thus, it is possible to have three HSZ disks of different sizes with duplicate serial numbers and V5 will treat them as unique disks. Three HSZ disks of the same size with duplicate serial numbers will be treated as three paths to a single volume, which ends badly. The same scenario is not a problem on V3 and V4 because they do not support multi-pathing.
When creating a custom disk size using the Avanti Configuration Utility, the disk type is assigned to HSZ22. If the disk serial number is left blank in the configuration file, FreeAXP assigns a fixed serial number to the HSZ disk: 00000002198505070c012c21bba00300. The structure of this serial number is important, as V5 recognizes it as a valid HSZ disk.
Unfortunately, if multiple HSZ disks are defined with blank serial number fields, they all get the same serial number: 00000002198505070c012c21bba00300. This is a bug in Avanti. This bug was not uncovered for many years, as HSZ disks with different sizes still appear unique to V5. It was only when a user defined several HSZ disks with the same size and blank serial number fields that the problem was diagnosed.
Automating a fix for this bug is problematic due to the large number of existing Tru64 UNIX installations. Hence, the fix for the HSZ duplicate serial number issue is a manual one. Here are the options:
- Vary the size of each HSZ disk and leave the serial number field blank. As long as all HSZ disk sizes are unique, V5 will accept them, even with duplicate serial numbers.
- Document the serial numbers used on a legacy HSZ installation and use them in the serial number fields of the Avanti configuration.
