Appendix C - SCSI ID Assignment Examples

The following scenarios show example SCAM Soft ID assignments (see 6.4.3). In all scenarios it is assumed that the host adapter has a Hard ID of 7.

SCENARIO 1: Four Devices:
- No Hard Ids
- Four SCAM devices; Default IDs 6,6,5,4.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 6 6

2 4 4

3 6 5

4 5 3


SCENARIO 2: Four Devices:
- No Hard Ids
- Four SCAM devices; Default IDs 6,6,5,4.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 5 5

2 4 4

3 6 6

4 6 3


SCENARIO 3: Four Devices:
- No Hard Ids
- Four SCAM devices; Default IDs 6,1,1,0.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 1 1

2 1 0

3 0 6

4 6 5


SCENARIO 4: Four Devices:
- Two Hard IDs, 6,4
- Two SCAM devices; Default IDs 6,6.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 6 5

2 6 3


SCENARIO 5: Four Devices:
- Two Hard IDs, 6,0
- Two SCAM devices; Default IDs 6,0.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 0 5

2 6 4


SCENARIO 6: Four Devices:
- Two Hard IDs, 6,0
- Two SCAM devices; Default IDs 0,0.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 0 5

2 0 4


SCENARIO 7: Eight Devices:
- Two Hard IDs, 6,0
- Six SCAM devices; Default IDs 6,6,6,6,6,6.

Isolation Requested Assigned
Sequence Default ID Soft ID

1 6 5

2 6 4

3 6 3

4 6 2

5 6 1

6 6 unassigned


Scenarios 8 and 9 illustrate that adding or removing SCSI devices does not impair the assignment of unique SCSI IDs through the SCAM protocol. SCSI ID conflicts are avoided, however SCSI IDs may change after the re-configuration. In these examples, the SCAM Devices are assumed to use SCAM strings of 'Device C', 'Device D', etc.

The following scenario illustrates the effect of adding and removing devices to a SCSI bus using a host adapter that does not save configuration information in nonvolatile memory.

SCENARIO 8: Initial Configuration of four Devices:
- Two Hard IDs, 6 (Device A), 4 (Device B)
- Two SCAM devices; Default IDs 6 (Device C), 6 (Device D).

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 4 B

1 6 5 D

2 6 3 C


- Add one Hard ID device 3 (Device E)
- Add one SCAM device with default ID 6 (Device F)

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 4 B

none none 3 E

1 6 5 F

2 6 2 D

3 6 1 C


- Delete one Hard ID device 4 (Device B)
- Delete one SCAM device with default ID 6 (Device D)

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 3 E

1 6 5 F

2 6 4 C


The following scenario illustrates the effect of adding and removing devices to a SCSI bus using a host adapter that saves configuration information in nonvolatile memory.

SCENARIO 9: Initial Configuration of four Devices:
- Two Hard IDs, 6 (Device A), 4 (Device B)
- Two SCAM devices; Default IDs 6 (Device C), 6 (Device D).

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 4 B

1 6 5 D

2 6 3 C


- Add one Hard ID device 3 (Device E)
- Add one SCAM device with default ID 6 (Device F)

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 4 B

none none 3 E

1 6 2 F

2 6 5 D

3 6 1 C


Note that device C had to be moved from ID 3 because a Hard ID device was added with ID 3.

- Delete one Hard ID device 4 (Device B)
- Delete one SCAM device with default ID 6 (Device D)

Isolation Requested Assigned
Sequence Default ID Soft ID Hard ID Device

none none 6 A

none none 3 E

1 6 2 F

2 6 1 C


No IDs were moved from the previous case.