Which device typically has a SCSi ID of?

Narrow SCSI tape drives are typically assigned IDs in the range 3-6 and are target devices, not the initiator that holds the reserved ID 7.

The SCSI host adapter defaults to SCSI ID 7, which carries the highest bus arbitration priority on a narrow SCSI bus (IDs 0-7), ensuring the controller can always win bus arbitration and manage all connected target devices reliably.

A bootable hard drive is conventionally assigned SCSI ID 0, which is the standard target ID for the primary boot device, not ID 7.

There is no special 'first device' designation at ID 7 - the first logical target on the bus is ID 0, while ID 7 is specifically reserved for the host adapter as the bus initiator.