Exabyte warnings, write retries

[lbd at alux4.att.com]

We have a 4/490 running 4.1, on which we run incremental and full dumps.
The dumps all seem to run just fine, but we get repeated warnings:

Aug 28 13:35:49 latin1 vmunix: st1:  warning, the tape may be wearing out or
Aug 28 13:35:49 latin1 vmunix:       the head may need cleaning.
Aug 28 13:35:49 latin1 vmunix: st1:  write retries= 1135 (60.3%), file= 0, block= 1880

The number of retries is usually in the same range, but the percentage of
retries varies, from 6% to 80%.  I realize that this is a warning, so it's
not hurting my dumps, but it is a pita, and my messages files fill up
awfully fast.

I talked to Mike Couch at Perfect Byte, and he said he's seen this problem
at 4.0.3, but never 4.1. We have a 3/280 running 4.0.3 and a 4/280 running
4.1, and neither of them has this problem. Could it have something to do
with 4.1 PSRA? I thought the PSRA just contained support for the IPI
drives. Could that have something to do with the SCSI driver?

We've replaced most of the hardware (drive, scsi board) and tried
different options to dump, but the warnings persist. We've cleaned the
drive repeatedly and tried a known good drive, but is still persists.

I've talked to our Sun PAL contact, and he hadn't seen it before. Our
hardware guy is stumped. Mike suggested there might be a patch from Sun,
or perhaps an adb patch someone on the net has come up with. Can someone
remove this annoyance??

Thanks for your response. I'll summarize to the net, if necessary.

Leslie Dreyer
Bell Labs, Allentown, PA
lbd at alux4.att.com