trouble communicating

[scottiep]

I'm getting the Error 102 (trouble communicating) with my backup to my AIT tape. I've changed the SCSI ID but this hasn't seemed to change anything. I've been using this system for a couple of years without any trouble--'til now. I had moved the workstation and now that I've moved it back, I'm getting the "communicating" error. I'm backing up a Mac server (AppleShare 6.1) from my G4 workstation over an ethernet network.

 

 

 

Could it really be the SCSI cable or terminator? Again, I changed the ID, but no change--plus, it's on a SCSI bus by itself. I'd try another cable, but it's a ultra-wide (I don't have easy access to another).

 

 

 

any help would be greatly appreciated.

[AmyJ]

The problem could stem from a SCSI issue, or a problem with the backup hardware itself. The only way to find the cause of the problem is to systematically rule out the different variables as follows:

 

 

 

1) A dirty tape drive or bad tape. Clean the drive using a cleaning cartridge. Try another tape. If other tapes work then you just have a tape with a spot that's bad enough to cause an error.

 

 

 

2) Another device on your SCSI bus is interfering with the tape drive's communication. Make sure your SCSI ID numbers are set correctly. Turn off your computer and the devices. Disconnect all SCSI devices except for the tape drive.

 

 

 

3) You have a bad cable. Replace the SCSI cable that connects the tape drive to the computer after removing other devices and cables from the SCSI chain.

 

 

 

4) You are missing a terminator (SCSI) or have a bad terminator. The last device and ONLY the last device in your SCSI chain needs to be terminated. Try replacing the terminator if you already have one on the chain.

 

 

 

5) The computer may be having a problem. Install Retrospect on another computer and try the tape drive there as the lone device on the SCSI chain.

 

 

 

6) The drive may be defective. If you have implemented all of the preceding steps and get failures on multiple tapes after changing cables terminators and computers then the drive (being the only factor that has not changed) is the culprit--send it back to your vendor for repairs.

 

 

 

The steps above are essentially the outline of our device troubleshooting here at Dantz. Hands on testing of device issues is really still the best method and even getting device logging information is usually only to confirm empirical testing. Note that concluding something is a bad device is the LAST thing we assume after all other components and variables have been ruled out. "SCSI voodoo" as they call the nebulous symptoms that can plague a SCSI bus can often lead one to false assumptions of the cause of problems. It's important that once a variable is tested that it be tested more than once for consistency's sake to rule out dumb luck. For example SCSI voodoo accounts for why a tape drive may work fine for many months without proper termination but then suddenly fail in some way later. Although customers will often cite that nothing has changed with their SCSI bus configuration in months and that it was all working before this is really indicative of the inconsistency of SCSI voodoo. The quickest and most conclusive test for most devices is to test it on more than one computer as the only device on the bus and with a different SCSI cable. If the problems can be reproduced on multiple computers it's more than likely a hardware problem with the device itself. Of course there a myriad of other specific issues having to do with a device's own hardware settings like with internal jumper cables dip switches or internal termination that has to be sorted out with the device's manual and/or vendor or manufacturer of the drive, but the kernel of SCSI troubleshooting above is a good general guideline.