Tape Drive

[Nobody's Hero]

Running Red Hat9. Operations told me there was a problem with the tape drive. I checked it out and it ran great. So I switched it to a new tape drive, still ran great. Then I put the original drive back in, now I get:

# mt -t /dev/st0 rewind
/dev/st0: No such device

How can I troubleshoot this. I checked all connectors, all looks good. I have power to the drive also. the OS just does not see it.

[Nobody's Hero]

in /var/log/messages, I used to see this:

piranha kernel: Attached scsi tape st0 at scsi1, channel 0, id 1, lun 0

Now I dont.

When I run:# cdrecord --scanbus
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 Jrg Schilling
Linux sg driver version: 3.1.24
cdrecord: Warning Linux Bus mapping botch.
Using libscg version 'schily-0.7'
scsibus1:
1,0,0 100) 'MegaRAID' 'LD0 RAID5 05006R' 'H ' Disk
1,1,0 101) *
1,2,0 102) *
1,3,0 103) *
1,4,0 104) *
1,5,0 105) 'HP ' 'SAFTE; U160/M BP' '1023' Processor
1,6,0 106) *
1,7,0 107) *
scsibus2:
2,0,0 200) 'TDK ' 'DVDRW420N ' '1.36' Removable CD-ROM
2,1,0 201) *
2,2,0 202) *
2,3,0 203) *
2,4,0 204) *
2,5,0 205) *
2,6,0 206) *
2,7,0 207) *

I dont see the tape device:

[Stuart Browne]

Is the tape internal or external?

If it's external, you'll need to either reboot or rescan the SCSI bus.

[Nobody's Hero]

How do you rescan the SCSI bus?

[Bejoy C Alias]

Try rebooting the machine and check 'dmesg' and see whether it is showing the dat drive detected during booting . Check whether the st module is loaded 'lsmod' .

[Simon Hargrave]

You can scan the SCSI bus in 2 stages: -

First probe the HBA's themselves. For example a QLogic HBA can be probed thus:

echo "scsi-qlascan" > /proc/scsi/qla2300/0 (and 1, 2 etc if you have multiple HBA's)

Cat the /proc/scsi/qla2300/0 file before and after so you can see if any new devices appear.

If you have HBA other than QLogic, try just "rescan" or check the docs for your HBA driver.

If your drive appears you can then add it to the SCSI layer: -

echo "add-single-device 1 2 3 4" > /proc/scsi/scsi

where 1 2 3 4 are controller, bus, target and lun.

Then run cat /proc/scsi/scsi to confirm it has been added.