SUMMARY: 4mm DAT tape dump options

From: Robin Kinzy (
Date: Thu Jul 07 1994 - 03:07:43 CDT

Greetings, all, and thanks to all who replied to my query. It and the
solution(s) follow, as well as a list of responders...

> What are the options for the 4mm DAT drive for dump? I don't see an
> example of it in any of the manuals, and want to use dump to our
> DAT drive for system backups. We are using 90m (295 ft) data grade
> tapes. Any suggestions or pointers to the manual would be greatly
> appreciated.

Georg Thimm ( sent the answer from SunSolve:

SYNOPSIS : dump command for 4mm tape drive


 The DAT Sun and IBB sell is a Data Compression DAT.
The recommended dump parameters are:

        dump 0ucbsdf 126 5000 61000 /dev/rst0 ........

126 = b = 63kbytes blocking factor ie the most the SCSI bus can handle.

5000 = s = ficticious length of tape so that dump doesn't exit early. for
parallel recording devices (eg. 9 track tape, QIC etc.) and the DAT is a
Helical Scan device.

 I know the above parameters work. I have had 417k/sec and
4.87Gb dumping to a DAT with these parameters (90M tape).
Obviously, this is going to vary depending on the data going to the
device and how much compression it can achieve.


see above
PRODUCT : dump_restore




[end of SunSolve solution]

There were as many dump option suggestions as there were
responses, and I'll include them below. I am using the configuration
above with no problems. Again, thank you to those who did reply.


From: (Michael Tong Lee)

I am a neophyte manager of a sun sparcstation IPC backing up onto
150 Mb Sony tapes QD 6150 which are 620 feet. What I gleaned from
man dump was to use:-

    dump 0custf 610 18 /dev/rst0 /dev/sd0a

for a 0 level dump to cartridge (1/4") leaving 10 feet for safety margin,
to file rst0 backing up the root directory sd0a


For 90m tape:
  size = 10240
  Density = 61000

        dump 0dsf 61000 10240 /dev/rst1 /dev/sd0g

From: Chris Wozniak TISC <>

I am using :
c (cartridge) , or equivalent b=buffer size=126;
s = tape size = 5000, fictitious value;
d = density = 61000, real tape density

dump bsdf 126 5000 61000 /dev/nrst8 .....

with the above I can get 4.9 Gb onto 90m tape in the compressing
device /dev/rst8

From: "Quinlan, Grant W." <>

We are using Solaris 2.3, and our DAT drives have the following
     b for BSD compatible tapes
     c for compression mode
     h for high-density mode
     l for low-density mode
     m for medium-density mode
     n for no rewind
     u for ultra mode
The default for any drive should be the highest density the drive can
handle. All the details are available using the "man st" command.

From: (Administrador do Sistema)

 Hi. I have a new SPARCserver 1000 with 4mm DAT drive. I didn't found
any information in the manuals too. I used:

        ufsdump 0ucdstf 54000 13000 126 /dev/rmt/0n /dev/dsk/....

and it worked, but i don't know if it's the best solution...

From: ianh@fruitbat.UK (Ian Herd - Sun UK - Answer Centre)

On solaris 2.X

ufsdump 0udf 126 /dev/rmt/0

you only need blocking factor, and that at the max is 126

size and blocking factor are not required on solaris 2.x as the drivers
handle end of tape sensibly, as do ufsdump.

From: (Elizabeth Thick x2688)

Just last night I compleated my first dump on my 4mm tape drive.
The parameters I found were in the Solaris 2.3 documentation. (I am
only running SunOS 4.1.3) The parameters I used are as follows:
That was with a 90m tape.

From: "Jerry.Hagon" <>

We are using

   /etc/dump 0ucsdf 15000 15000 /dev/nrst0 /dev/sd1a

From: Jeffrey Marans <>

The archive ST2000 and ST4000 use
       /usr/etc/dump 0dsf 610000 15360 /dev/nrst1 /dev/rsd0a

under 4.1.3.

The recommended tape length parameter is 10240, but Conor tech
support tells me 15360 gives better results.


mine are dump *ubdsf 512 61000 10240 /dev/rst24

From: Carl.Meske@Eng.Sun.COM (Carl Meske)

this is what I use on my system running Solaris 2.3:

this is the csh pgm

#! /bin/csh -f

set Date = `date +%m%d%y`
set DumpDir = /usr/sbin # location of ufsdump
set DumpCmd = $DumpDir/ufsdump # use ufsdump
set DumpDevice = /dev/rmt/1n # no rewind
set DumpParams = '0usdf 13000 54000' # 4mm DAT params
set NRdumpDevice = /dev/rmt/0 # rewind device

# get list of raw devices that are ufs paritions from /etc/vfstab
set DumpFiles = `grep -v '^#' /etc/vfstab | grep ufs | cut -f2`

# backup the disks....

echo ">>>> System backup Begun. `date`"

foreach Partition ($DumpFiles)
  echo $Partition
  $DumpCmd $DumpParams $DumpDevice $Partition

...and the following gives a lot of good info if you have
an HP drive...

From: bern@penthesilea.Uni-Trier.DE (Jochen Bern)

Just in Case that your DAT happens to be a HP 35480A Drive:


Seeing all these Posts about "How to connect DATs", I conclude that us
Krauts are just lucky since HP gives us a good, usable How-To Sheet.

Here's my That's_About_It (tm) Translation; I put "<!>" wherever the
Info could be subject to a Housing supplied / Assembly done by your


HP 35480A

Jumper Switch Settings

<Jumpers are numbered 1-5 from the Middle of the Rear View to the
1: term power
2: SCSI Id Bit 0 (1)
3: 1 (2)
4: 2 (4)
5: DC on/off using ext. Cable

<!> Assembled Subsystems will have Switches on the Back to set the
<!> We deliver the Drive with Id 4 (/dev/rst0).

Further Configuration can be done with the Dip Switches on the Bottom
the Device. Set the Switches to 1, 2 on, 3 off, 4, 5 on, 6, 7, 8 off


<!> We deliver the Drive with Terminators pulled out.

LED Status Codes

Green - Blink.Green: Caution, Media Wear.
Amber - Amber: Termination / high Humidity
Blink.Amber - Blink.Amber: Self Test in Progress
Blink.Amber - off: Self Test failed


1. In /sys/scsi/targets/st_conf.c, add: <Note that this seems to mean
                                            only SunOS 4.1.x, or am I wrong?>
   /* HP DAT HP35480A */
      "HP35480A", 2, "HP", ST_TYPE_EXABYTE, 1024,
      ( ST_VARIABLE | ST_BSF | ST_BSR ),
      5000, 5000,
      { 0x00, 0x00, 0x00, 0x00 },
      { 0, 0, 0, 0 }

2. cd /sys/sun4c/conf <Note that this assumes you use
   config GENERIC a sun4c Machine and a GENERIC
   cd ../GENERIC Kernel, and that you're currently
   make logged into THAT Machine, AND
   mv /vmunix /vmunix.old that it is where you build Kernels,
   mv ./vmunix /vmunix too>

3. Reboot

4. Dump with:

   dump 0ubdsf 126 27000 <Size> /dev/rst0 /dev/sdXX

   where /dev/sdXX is the Drive you want to dump, and Size is:
   60 m Tapes: 24000 compressed, 6000 non-compressed
   90 : 36000 9000

   <and where you should replace /dev/rst0 with the Device Name you
   used for the DAT Drive :-)>


Compression can't be software controlled on SUNs; You have to
manipulate the
first two Dip Switches. If both are on, Compression is on.
<!> We deliver the Device with Compression turned on.


For those of you who have made it this far, thanks again
to the above people for helping out. Hope this helps
others who have the same question.

Robin R. Kinzy Voice: (801) 378-7388
Brigham Young University Fax: (801) 378-2800
310A SFLC Email:
Provo, UT 84602

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