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Kyle
Asked: 2009-06-09 10:01:30 +0800 CST

Linux machine can't find its tape drive

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I have an older HP NetServer LPr with what is apparently a Symbios SCSI card connecting to a Quantum SuperLoader 3 that is DLT based. From time to time, we seem to lose the connection to the autoloader. It's usually due to flaky power, but not totally sure why; sometimes when this happens the Autoloader's LED's are orange and it needs to be power cycled. The annoying workaround currently is to reboot the machine. As it is our production VPN and DNS server in addition to being our backup server, this is less than optimal.

In Debian (Sarge) is there not some command one can type to get the card to notice that it has the autoloader connected again?

dcr1:/proc# grep -i symbios /proc/pci
    SCSI storage controller: LSI Logic / Symbios Logic 53c895 (rev 1).
dcr1:/proc# uname -a
Linux dcr1 2.4.27-3-686 #1 Tue Dec 5 21:03:54 UTC 2006 i686 GNU/Linux
dcr1:/proc# mt status
mt: /dev/tape: No such device
dcr1:/proc# ls -l /dev/tape
lrwxrwxrwx 1 root root 8 2007-02-07 16:01 /dev/tape -> /dev/st0
dcr1:/proc#

That mt status command will show the actual st0 status when things are working correctly. The No such device message is usually the second clue that we need to reboot - the first clue is usually that the backups didn't run.

linux scsi autoloader dlt

4 Answers

  1. Best Answer

    On Linux 2.4 you can force a scsi bus rescan by sending 'echo 1' to one of the /proc entries. I always looked it up in the SCSI_HOWTO document. I can look it up if needed.

    It sounds like the drive is going offline. Have you tried the scsitur (test unit ready) or the scsinq command ?

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  2. Have you tried removing and re-adding the 'st' (scsi tape) module? Might prevent the need for a reboot at least...

    lsmod | grep st
sudo rmmod st
sudo modprobe st
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  3. Maybe you need to delete the scsi device and then force a rescan. This IBM article has some ways of doing this.

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  4. When your drive is detected correctly, run the command : 

    # cat /proc/scsi/scsi

    and note down the result.

    it should look like :

    Host: scsi9 Channel: 00 Id: 01 Lun: 00
  Vendor: IBM      Model: ULT3580-TD4      Rev: 5500
  Type:   Sequential-Access                ANSI  SCSI revision: 05

    on 2.4 kernels : 

    # echo "scsi add-single-device H C I L" > /proc/scsi/scsi

    where H C I L are the SCSI address whenever the drive is detected correctly

    on 2.6 kernels : 

    # echo “- - -” >  /sys/class/scsi_host/hostH/scan

    where H is the number of the SCSI controler.

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