topic Re: /dev/rmt/0m gets lost occassionally in Operating System - HP-UX

/dev/rmt/0m gets lost occassionally

Mike Gordon — Tue, 20 Jun 2000 08:18:12 GMT

Every now and then we have a backup failure with cpio reporting '/dev/rmt/0m - no such device or address'. ioscan shows the tape as present and claimed, the device files are all listed. cstm reports no problems with the drive and a re-create of the device files via SAM makes no difference.

The only solution to this is to power off the machine to re-initialise the DAT drive.

Any suggestions as to the cause of this problem will be much appreciated.

Re: /dev/rmt/0m gets lost occassionally

CHRIS_ANORUO — Tue, 20 Jun 2000 09:12:19 GMT

Mike check this link:
http://europe-support2.external.hp.com/cki/bin/doc.pl/sid=879e601c00b4520b3e/screen=ckiDisplayDocument/distrib_redir=1+961495635|*?docId=200000047385470

Re: /dev/rmt/0m gets lost occassionally

Mike Gordon — Tue, 20 Jun 2000 09:19:26 GMT

Thanks for your quick response. We use cpio for our backups as part of an automated scriot. The error message however is not connected just to cpio. I get the same message if I try tar or a simple mt command such as 'mt -t /dev/rmt/0m rew'.

Have included following info incase this helps :

/tmp#lssf /dev/rmt/0m
stape card instance 1 SCSI target 0 SCSI LUN 0 at&t best density available at ad
dress 8/16/5.0.0 /dev/rmt/0m
/tmp#ioscan -funC tape
Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
tape 0 8/16/5.0.0 stape CLAIMED DEVICE HP C1537A
/dev/rmt/0m /dev/rmt/c1t0d0BESTn
/dev/rmt/0mb /dev/rmt/c1t0d0BESTnb
/dev/rmt/0mn /dev/rmt/c1t0d0DDS
/dev/rmt/0mnb /dev/rmt/c1t0d0DDSb
/dev/rmt/c1t0d0BEST /dev/rmt/c1t0d0DDSn
/dev/rmt/c1t0d0BESTb /dev/rmt/c1t0d0DDSnb
/t

Re: /dev/rmt/0m gets lost occassionally

CHRIS_ANORUO — Tue, 20 Jun 2000 10:11:34 GMT

Goto /dev and use the insf command.
Eg insf -d driver or -D /dev/rmt/0m

I thing it will help.

Re: /dev/rmt/0m gets lost occassionally

Robert Gamble — Tue, 20 Jun 2000 11:04:32 GMT

the quick & dirty way to recreate device files is to issue 'insf -e' as root. it will recreate _all_ device files for all devices seen.

Re: /dev/rmt/0m gets lost occassionally

Alan Riggs — Tue, 20 Jun 2000 12:53:50 GMT

On enote: Care should be taken before issuing an insf -e as root.

While I have done this myself on several occassions without problem, it is possible to corrupt open interfaces and leave devices in an indeterminate state. The standard recommendation (see man insf) is to go to single-user mode before issuing insf. The danger, of course, is reatly minimized by use of the -H flag (or -C -I).

Re: /dev/rmt/0m gets lost occassionally

Robert Gamble — Tue, 20 Jun 2000 19:08:42 GMT

Alan, thats why I said quick and 'dirty'.
It was not meant to solve this problem, but to include that command for archive sake. ;)

Re: /dev/rmt/0m gets lost occassionally

Carlos Fernandez Riera — Wed, 21 Jun 2000 07:07:32 GMT

Hi all:

Refresh special files is a good idea, but "no such device or address'" it just a sintoma of problems with tape and drives.

Realy what it mean is that drives in not ready, and may be by many reasons :

- Driver is yet loading tape
- Bad cable, or terminator connections.
- Timeouts in SCSI channnel.
- Bad tapes or faulty drives.
- software problems, specialy with cpio.

Many times after this message the tape IS REWINDED, so next command can override previous data in tape.

Run dmesg and see /var/adm/syslog/syslog.log.
Read tapes after this error.

Be care.