The target addressing method (described above) used by your device.
Existing addresses on the interface - All devices must have a unique target ID.
Device type - some device types such as CD-ROM and tape drives are most easily identified by the operating system when they are with certain addresses. See the table below:
Device Order | CD-ROM Targets | Tape Target | Disk Target (Ultra & Enterprise Systems) | Disk Target (Pre-Ultra systems) |
---|---|---|---|---|
1st | 6 | 4 | 0 | 3 |
2nd | 5 | 1 | 1 | |
3rd | 2 | 2 | ||
4th | 3 | 0 | ||
5th | 4 | 4 | ||
6th | 5 | 5 | ||
7th | 6 | 6 |
Some SCSI controllers support 7 devices, others support up to 15 devices (although you should take into account the effect on I/O). If 15 devices are connected, valid disk target IDs are 0-14.
You can not have two devices with the same Target ID on the same SCSI controller. However, target IDs can be reused across different SCSI controllers.