DLT tape drive usage & install

Constance Sieh (csieh@fnal.gov)
Mon, 25 Jan 1999 12:17:41 -0600 (CST)

Info about use of DLT tape drives on Linux

Yes - we've used 4000's and 7000's.

The devices to use are /dev/st0 and /dev/nst0 (the rewind and no-rewind
devices) for the first drive, /dev/st1 and /dev/nst1 for the second
drive, and so on.

These will only work if the SCSI tape driver is loaded. Under RedHat,
the driver (st.o) should be included in the /lib/modules/ area.
As root, you can load with
/sbin/insmod st

I've also used /etc/conf.modules to automatically load SCSI and st
drivers (via kerneld). I recommend against this, however, because
if only tape drives are on your SCSI bus, a period of inactivity will
cause the kernel to unload the SCSI device driver (and st.o). At the
next tape activity request, the SCSI driver will be reloaded. By
default, this causes a SCSI bus reset, which causes tape drives to
rewind. Any subsequent write to the tape drive can overwrite data.

Another thing to watch out for is the block size to be used on your DLT's.
By default, the maximum block size set by the kernel is 32K. If you
need larger blocks, add a line (for 64K blocks)
to your /etc/lilo.conf file. The largest block size allowed is a smidgen
under 128k. For details, see

Once you've installed the mt-st rpm, you should be able to look at the
mt man page with 'man mt'.

You should not be trying to mount tape drives. Once st.o is loaded, you
can use mt to check on the status of a drive:

rip1:~# mt -f /dev/nst1 status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x0 (default).
Soft error count since last status=0
General status bits on (40010000):

You then can use any I/O command (dd, tar, cpio, etc...) to read/write from
/dev/nstx. You do not need to format a DLT cartridge.

If you're having troubles, execute
cat /proc/scsi/scsi
to make sure that your system is seeing your tape drive:

rip1:~# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: SEAGATE Model: ST34572W Rev: 0784
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 01 Lun: 00
Vendor: SEAGATE Model: ST34572W Rev: 0784
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi2 Channel: 00 Id: 01 Lun: 00
Vendor: QUANTUM Model: DLT7000 Rev: 1E48
Type: Sequential-Access ANSI SCSI revision: 02

Here, my first SCSI interface has two Seagate disks attached ("Direct-Access"),
and my third SCSI interface (scsi2) has a DLT7000 attached ("Sequential-Access").
If you can't find SCSI tape drives in /proc/scsi/scsi, nothing else will work.

Don Holmgren

> Hello, all.
> Does anyone have any experience using Quantum DLT 4000 series drives? I
> have two new systems running Red Hat 5.0 (with some necessary XFree
> upgrades) which both have a DLT drive, and I can't find a device in /dev
> which doesn't come back with
> Not a valid block device
> when I try to mount it. Do I need to format the tape cartridge first?
> How? I have installed the mt-st rpm, but it doesn't seem to have a man
> page....
> Thanks,
> Jason Galyardt
> Texas Tech University
> galyardt@aardvark.phys.ttu.edu