Jerry,

A couple of things:

Perhaps the tape drives are dirty.  Try cleaning them.

Perhaps the element/scsi IDs are mismatched.  When the drives are defined in
the library the syntax of the command is define drive libname drivename
device=mt2.0.0.3 element=500 (note that the device and element numbers I've
provided here are bogus).  If you mix up them up when defining two drives,
TSM will put a tape in one and expect to read it on the other resulting in
an I/O error.  To determine if this has happened, open a command window on
your server:

cd program files\tivoli\tsm\utils
libtest -dev lbx.x.x.x (find the values of x in the TSM Server Utilities
device manger window, swiss army jackknife on your desktop)
Choose manual test
Choose number 6, open
Choose number 8
Choose number 9.

Scroll up through the list and find the drive definitions.  You will be
shown the element ID and the SCSI ID for the drives.  Compare this to what
you have in TSM:

tsm> q drive f=d

If they aren't the same, update the drives:

update drive libname drivename element=thecorrectelement

How would this problem have happened?  Who knows, perhaps someone messed
with it and didn't understand what they were doing.

If this all fails, try a reboot.  Tighten all the cables going to the
library.  Power off the library and power the whole mess back up library
first.  Watch the bios banner to ensure the bios sees the drives.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs, CO 80949
lipp AT storsol DOT com or kelly.lipp AT storserver DOT com
www.storsol.com or www.storserver.com
(719)531-5926