What serial numbers are

A serial number (SN) is a unique identifier for a tape drive or a medium changer. Starting with Data ONTAP 8.2, Data ONTAP generates aliases based on SN instead of the WWN.

Since the SN is a unique identifier for a tape drive or a medium changer, the alias remains the same regardless of the multiple connection paths to the tape drive or medium changer. This helps storage systems to track the same tape drive or medium changer in a tape library configuration.

The SN of a tape drive or a medium changer does not change even if you rename the Fibre Channel switch to which the tape drive or medium changer is connected. However, in a tape library if you replace an existing tape drive with a new one, then Data ONTAP generates new aliases because the SN of the tape drive changes. Also, if you move an existing tape drive to a new slot in a tape library or remap the tape drive’s LUN, Data ONTAP generates a new alias for that tape drive.

Attention: You must update the backup applications with the newly generated aliases.

The SN of a tape device uses the following format: SN[xxxxxxxxxx]L[X]

x is an alphanumeric character and LX is the LUN of the tape device. If the LUN is 0, the LX part of the string is not displayed.

Each SN consists of up to 32 characters; the format for the SN is not case-sensitive.