Retrospect: Troubleshooting SCSI Issues
This article describes how to troubleshoot SCSI issues when using Retrospect.
SCSI Issues
If the Macintosh SCSI chain is not set up properly, communication errors may occur, when using Retrospect, that can cause data corruption or system failures during backup operations. This section is designed to give you guidance when encountering SCSI issues.
Some devices such as scanners, CD-ROM drives, or external SCSI floppy drives can cause issues on the SCSI bus, especially if they are turned off. If you are experiencing SCSI communication issues, make sure that all of your SCSI devices are turned on when you start your Macintosh.
The following sample errors can indicate communication errors on the SCSI bus:
* File "Home" didn't compare at resource offset 10,750
* File "Tech Note" didn't compare at data offset 3,253
* Trouble writing: "1-Office Backup 2" (0), error 102 (trouble communicating)
* Trouble reading: "1-Office Backup 2" (0), error 102 (trouble communicating)
The above errors can usually be traced to some failure in the SCSI configuration, whether it is termination, a particular device, cabling, or device order. The most common cause of communication issues is improper termination or bad SCSI cables.
Termination
The general rule for termination is to have only two terminators on the SCSI bus, one at the beginning and one at the end. If you have only a single device on the SCSI bus, then only one terminator is needed. Most Macintosh computers purchased with internal hard disks are internally terminated. Some SCSI peripherals come with internal termination built-in, and must be placed at the end of a SCSI chain. For more information, refer to your Macintosh user's guide and the manual that came with your hardware device.
SCSI Cables
Communication issues can be caused by bad or loose-fitting SCSI cables. Check all cables for proper seating in each connector. The entire length of your SCSI bus should not exceed 20 feet. Whenever possible, avoid using cables over six feet in length.
Device Order and Device Conflicts
To avoid issues caused by device order or device conflicts, make sure that each device has a unique SCSI address. If issues occur, try changing the order of SCSI devices or temporarily removing unneeded devices.
For further information on working with Retrospect and Retrospect A/UX, search the Tech Info Library by "Retrospect" or "Remote."
If the Macintosh SCSI chain is not set up properly, communication errors may occur, when using Retrospect, that can cause data corruption or system failures during backup operations. This section is designed to give you guidance when encountering SCSI issues.
Some devices such as scanners, CD-ROM drives, or external SCSI floppy drives can cause issues on the SCSI bus, especially if they are turned off. If you are experiencing SCSI communication issues, make sure that all of your SCSI devices are turned on when you start your Macintosh.
The following sample errors can indicate communication errors on the SCSI bus:
* File "Home" didn't compare at resource offset 10,750
* File "Tech Note" didn't compare at data offset 3,253
* Trouble writing: "1-Office Backup 2" (0), error 102 (trouble communicating)
* Trouble reading: "1-Office Backup 2" (0), error 102 (trouble communicating)
The above errors can usually be traced to some failure in the SCSI configuration, whether it is termination, a particular device, cabling, or device order. The most common cause of communication issues is improper termination or bad SCSI cables.
Termination
The general rule for termination is to have only two terminators on the SCSI bus, one at the beginning and one at the end. If you have only a single device on the SCSI bus, then only one terminator is needed. Most Macintosh computers purchased with internal hard disks are internally terminated. Some SCSI peripherals come with internal termination built-in, and must be placed at the end of a SCSI chain. For more information, refer to your Macintosh user's guide and the manual that came with your hardware device.
SCSI Cables
Communication issues can be caused by bad or loose-fitting SCSI cables. Check all cables for proper seating in each connector. The entire length of your SCSI bus should not exceed 20 feet. Whenever possible, avoid using cables over six feet in length.
Device Order and Device Conflicts
To avoid issues caused by device order or device conflicts, make sure that each device has a unique SCSI address. If issues occur, try changing the order of SCSI devices or temporarily removing unneeded devices.
For further information on working with Retrospect and Retrospect A/UX, search the Tech Info Library by "Retrospect" or "Remote."