*BSD News Article 51065


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From: kelly@emu.fsl.noaa.gov (Sean Kelly)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: dump parameters for DAT tape?
Date: 16 Sep 1995 23:40:35 GMT
Organization: Forecast Systems Laboratory
Lines: 43
Message-ID: <43fn9j$rn1@CUBoulder.Colorado.EDU>
References: <ts-1609952006280001@mac.infodirekt.com>
NNTP-Posting-Host: emu.fsl.noaa.gov

In article <ts-1609952006280001@mac.infodirekt.com>,
Thomas Schreiber <ts@infodirekt.com> wrote:
>What are the best values for the dump parameters d, s, and b for HP C1533A
>DAT Drive (16 GB max.) with

I don't use the d and s parameters with my DAT drive (Wangtek 6130HS)
since it can reliably detect end of tape.

When I type

	mt -f /dev/rst1 status

it tells me the accepted blocksize is variable.  I experimented with
dd and a number of block sizes and found:

     Block Argument                          Rate
      Size Specified            Bytes   bytes/sec

       512 none, default    562819584       24571
      1024 1k               475142144       67053
      1024 1k               476026880       67131
      2048 2k              1087369216      153323
      4096 4k              1280540672      180281
      8192 8k              1287610368      181302
     32768 32k             1287651328      180875
     51200 100b            1289676800      181134
    512000 1000b           1290752000      181285
   5120000 10000b          1290240000      181238

For dump, I use the following command for each <filesystem>:

	dump <level>nubBf 64 999999 /dev/nrst1 <filesystem>

and dump four filesystems of one disk onto a tape each month at level
0 and every other day at level 5.

-- 
Sean Kelly
NOAA Forecast Systems Lab, Boulder Colorado USA

To me, clowns aren't funny. In fact, they're kind of scary. I've
wondered where this started, and I think it goes back to the time I
went to the circus, and a clown killed my dad.  -- Jack Handey