SUMMARY: dumping to a 5Gb 4mm dat tape

From: Andrew George (andrew%mclbris2@mitsui.oz.au)
Date: Thu Jun 09 1994 - 17:27:39 CDT


Dear Sun Mangers

Thankyou all For your responses Re Dumping to 4mm Dat drive using Solaris 1.1.1.
It seems that a few of you have found the same problem.

Here is what I originally posted:

----- Begin Included Message -----
Hi Sun-managers,

When dumping to a Sun 4mm Dat drive, using Solaris 1.1.1, I can only backup
aprox 2.5GB of data using rst0 and about 3.5GB of data using rst8.
The tape is 90m long. Should I be using a tape length of 120m?

Can anybody tell me what the correct parameters are for Dump using a 4mm Dat
drive under Solaris 1.1.1?

Answerbook for Solaris 2.3 says to use a blocking factor of 96 whereas
a document in sunsolve says to use 126.
  
Which is right? Any other hints or tips?

Thanks in advance....

Andrew.

----- End Included Message -----

The concensus seems to be if you want to get anything close to 5Gb on a dat
tape, then the device must be /dev/rst8 or higher. eg, rst16, rst32.

120m tapes are only for the newer DDS-II tape drives.

So far I've used the parameters from Chris Wozniak below and am getting alot
closer to the 5Gb SUN advertise.

Chris Wozniak TISC <chris@tisc.edu.au>

b-factor of 126 is OK, or you may use c (cartridge) switch with the
same effect.
Use:
s = size = 5000 ficticious tape length
d = density = 61,000 real tape density.
Send to rst8, rst16 or rst32.
I've tested it with above parameters and got 4.9 GB onto tape,
close enough to the spec.
>

Many thanks to Chris and the following Sun Managers who also replied with
slightly different parameters and suggestions :-

davee@lightning.mitre.org (David N. Edwards)
Here's what I use (Sparc-2 with Sun's DAT drive,
Running Solaris 1.1.1_U1 not rev. B, 90M tape):

        /usr/etc/dump 0ubsdf 96 7142 61000 /dev/nrst0 ${FILESYS}

The lenths people suggested from the net were: 10240 for 90M tapes, and
                                                6656 for 60M tapes.

Martin Kalugin <martink@cent1.lancs.ac.uk>
I use the follwing parameters:-

dump 0udsbf 61000 10240 96 /dev/nrst8 /dev/sd0g

Eric.Olemans@esat.kuleuven.ac.be

Andrew,
these are the options I use, and they seem to be working fine :

                0dsbfu 54000 6000 96

Dave Mitchell <D.Mitchell@dcs.shef.ac.uk>

Sun's "5Gb" drive is a 2Gb drive + compression. Getting 3.5Gb in
compressed mode is reasonable, 5Gb is unrealistic. Complain to your
nearest Sun salesman about marketing hype....

>The tape is 90m long. Should I be using a tape length of 120m?

No. 120M tapes are only suitable for certain types of drive (DDS-2)
which I dont believe Sun's drive is.

>Answerbook for Solaris 2.3 says to use a blocking factor of 96 whereas
>a document in sunsolve says to use 126.

shouldnt make that much difference - I'd recommend 126.



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