Here I sit with a new (to me) Compaq GB 15/30 DLT. I was assured by the previous owner that it works perfectly. Now...

With mt-st and mtx I can control the drive and changer as expected. Retension, erase, load/unload, and so on... no problems.

Any attempt to write however, locks up the system immediately after the tape drive is accessed. Type or age of tape doesn't seem to matter.

Nothing is written to the syslog or messages files which gives even the faintest hint of the problem.

Any suggestion as to where to start troubleshooting would be appreciated!

Is it a SCSI tape drive? Do you have any other SCSI on the system (like your hard disk for example)? If so have you verified each device has a separate SCSI ID (including the SCSI adpater itself)? Also is the SCSI ID of the adapter correct? (Typically had to have the highest ID of all - disks next and tape drives last so that priorities were correct within the SCSI bus - I did work on IBM machines once upon a time that required the adapter to have ID 0 instead of highest). Do both ends of the SCSI chain have terminators or built in termination?

Yes, it is a SCSI tape drive; the entire system is SCSI and is based around an Adaptec 1542B. There are no device id conflicts, and the host adapter is set at #7.


Yes... I think.

Internal termination is fine, however for reasons unrelated to this thread I unplugged my one and only external device a while back. Your question about termination suddenly has me wondering whether or not I remembered to connect a terminator in place of the removed device.

No worries after all... I just verified that termination is present at both ends of the chain.

Something I forgot to mention in my previous post, is that there do not appear to be any problems with any of the other SCSI devices.

Still looking for help troubleshooting this... not having a backup solution is creeping me out.

The hang really makes me think there is an issue with the SCSI IDs. I recall working on PCs in the past where the IDs were odd. I always had to set the tape drives to ID 2 and (I think) the hard drive to ID 6 (may have been - that weird IBM setup again).

Try insuring the hard drive's ID has higher ID (therefore higher priority) than the tape drive.

Interesting... I'll give it a shot.

As a rule of thumb I've always assigned the higher IDs to the slower devices such as CDROMs and tapes. ISTR reading more than one article which suggested that it was best to give the slower devices the higher priority.


Further experimentation BTW, suggests that it's not a total OS hang in the usual sense. The SSH server daemon, and which ever process responds to console logins become unresponsive, but other processes such as iptables and pppd continue to function. Still, with no ability to open a terminal and intervene, it might as well be a total hang.

Finally found the problem; it's a simple matter of hardware incompatibility.

While I was aware that the AHA-1542 can't operate a hard drive in excess of 4GB, it never occurred to me that a similar limitation may exist with higher capacity tape drives.

When tested in another system which uses a 2940UW, the drive behaves flawlessly. Looks like it's time to upgrade the Linux box.