Help: Problem with backup, scsi transport failed

Hi,
I got a problem on my backup server again and need help. Thanks in
advance.

The backup acted weird today while I was replacing the tape. At first,
I could not remove the volume index out of the pool. After I fixed
this problem and tried to label the tape. It gave me the error on each
tape, said that bad file number. I have successfully finished labling
three tapes. At the fourth tape, it took more than half an hour, but
was still not done. So cancelled the operation of labeling. The
problem happened during the cancelling. The scsi error occurrs, had
the error message: Read open error, I/O error. The autochange stops in
the middle of the CY-TL8-2015 tape library subsystem. The light is
green for the autochanger. Then I opened the door, found the tape is
still mounted. After close the door, the light of the autochager stay
in red. Then I checked the log file , have some error messages like
this:

Sep 27 17:32:17 beverly unix: SCSI transport failed: reason
'timeout': giving
up^M^M
Sep 27 17:32:17 beverly root: Solstice Backup media: (warning)
/dev/rmt/1mbn rea
ding: I/O error

Sep 27 17:45:03 beverly unix: Disconnected command timeout for
Target 1.0
Sep 27 17:45:04 beverly unix: NOTICE: lus_intr(1.1.0): transport
failure (timeou
t)
Sep 27 17:46:05 beverly unix: NOTICE: lus_intr(1.1.0): transport
failure (incomp
lete)


The server is running SUNOS 5.6 with RAID 5 external hard disks and
backup file is solstice 5.1.

I have checked the /kernel/drv/st.config. Nothing was wrong there.

Any suggestion?

Mei