LFCS · Question #742
You ran out of space and added a eighth disk to your SCSI-1 system. When you try to start, the system no longer boots. What is most likely the cause of this problem?
The correct answer is A. SCSI-1 supports only 8 devices including the adaptor. The system failed to boot after adding an eighth disk because SCSI-1 (Narrow SCSI) has a physical limitation of 8 devices, including the host adapter itself.
Question
Options
- ASCSI-1 supports only 8 devices including the adaptor.
- BSCSI-1 supports only 6 disks per adaptor.
- CThere is a SCSI-ID conflict that causes that problem.
- DYou forgot to set the SCSI-ID #8 for the new disk.
How the community answered
(19 responses)- A89% (17)
- B5% (1)
- C5% (1)
Why each option
The system failed to boot after adding an eighth disk because SCSI-1 (Narrow SCSI) has a physical limitation of 8 devices, including the host adapter itself.
SCSI-1 (also known as Narrow SCSI) specifies an 8-bit bus, which allows for a maximum of 8 devices on the bus. Since the host adapter itself consumes one of these device slots, only 7 additional peripheral devices (like disks) can be connected, and adding an eighth disk would exceed this limit, causing system boot failure.
SCSI-1 supports 7 peripheral devices plus the adapter, not specifically 6 disks.
While SCSI ID conflicts can cause issues, the primary problem here is exceeding the device limit, which implicitly causes a conflict for the 8th device slot.
Setting SCSI ID #8 is not an option as SCSI-1 IDs range from 0-7, and ID 7 is typically reserved for the host adapter, leaving IDs 0-6 for devices.
Concept tested: SCSI-1 device limit
Source: https://www.ibm.com/docs/en/aix/7.2?topic=protocol-scsi-specifications
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