Reconciling Minor Numbers for NFS Shared Disks
To ensure proper failover of NFS, the minor numbers of block devices have to exactly match on all systems. The minor numbers are encoded as hexadecimal digits in the pattern XXYZZZ, where XX indicates the ICIN (Interface Card Instance Number), Y indicates the SCSI ID of the device, and ZZZ indicates the LUN.
As seen from two systems, a shared SCSI device will have the same the SCSI ID and the same LUN. However, the interface card instance number, which is automatically assigned by the kernel based on how the hardware is connected, could differ. For example, the device file for the SCSI card for the same device could appear as:
On System A:
brw-r----- 1 bin sys 31 0x019000 Dec 3 11:50 /dev/dsk/external_disk
On System B:
brw-r----- 1 bin sys 31 0x029000 Dec 3 12:05 /dev/dsk/external_disk
Note that the minor numbers differ only in the ICIN digits, as explained above.
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