SUMMARY: Digital Linear Tapedrive (DLT) information

From: Bob Reardon (
Date: Mon May 23 1994 - 14:34:06 CDT

I recently asked whether anybody had experience with Digital Linear Tape
drives (DLTs) on Sun workstations. Some folks also wanted to hear more but
nobody responded with information. I was able to borrow a DLT and try it on
an IPX and a Sparc10-51 running SUNOS4.1.3. The IPX had external Micropolis
1924 disk and the Sparc10 had internal Sun1.05 disk. Here are some things
we learned.
 - The DLT is very fast. When dumping large files from the 10-51 it maintained
        approximately 700kb/sec ( or 2.5 GB/hour) at 6GB density setting.
        At 10GB density setting, it actually ran slower; apparently the
        workstation could not provide data fast enough to keep the DLT
        in streaming mode.
        When dumping a partition of smaller files, such as /usr, the speed
        of the disk always determined dump speed - approx. 400kb/sec on
        the IPX at any DLT recording density .
 - It runs as an "st" device but you need to add a few lines to the stdef.h
        and st_conf.c kernel files. Tape movement commands such as
        mt -f /dev/rst9 eom are executed correctly and the "s" option in
        restore finds the correct dump file on tape.
 - The DLT we used has 4 density/capacity settings:
        2.6 GB, 6.0 GB, 10.0 GB, 10.0 GB-with-compression. All are selected
        manually from front panel with indicator light to show which is
        being used.
 - Didn't have time to see how many Gbytes the tape would hold at
        maximum density...

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