From owner-freebsd-scsi  Sat Jul 28 13:12:13 2001
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Date: Sat, 28 Jul 2001 13:11:56 -0700 (PDT)
From: Matthew Jacob <mjacob@feral.com>
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To: scsi@FreeBSD.ORG
Subject: Re: DLT 4000 throughput and cstream
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[ -hardware trimmed- Only one list is needed ]


> >   KB/t tps  MB/s
> >  60.59  22  1.31
> >  60.59  22  1.31
> >  61.05  22  1.31
> >  60.62  22  1.32
> >  60.59  22  1.31
> >  ...

This is about half the speed you should expect.

Testing with dump, w/wo cstream, is not helpful. You need to test with a
non-zero data generator:

yorp.feral.com > root camcontrol devlist
<SEAGATE ST39175FC 0001>           at scbus0 target 129 lun 0 (pass0,da0)
<SEAGATE ST39175FC 0001>           at scbus0 target 130 lun 0 (pass1,da1)
<SEAGATE ST39175FC 0001>           at scbus0 target 131 lun 0 (pass2,da2)
<SUN DLT4000 CC2D>                 at scbus2 target 2 lun 0 (sa0,pass3)
<HP C1537A L609>                   at scbus2 target 3 lun 0 (sa1,pass4)
<TANDBERG SLR5 4/8GB =09:>         at scbus2 target 6 lun 0 (sa2,pass5)
yorp.feral.com > tape_pattern_tester 
tape_pattern_tester: [ -v ] [ -b blksize ] [ -r blocks per file ] [ -n
number-of-files ] -f no-rewinding-tape-drive
yorp.feral.com > tape_pattern_tester -v -b 32k -r 1000 -n 5 -f /dev/nsa0
.......Rewind Tape
........Write Pass
EOT at File 4 Record 1000 Offset 32768 (163840000 total bytes written)
Elapsed Seconds: 60; Data Rate: 2.6MB/s
.......Rewind Tape
.........Read Pass
EOT at File 5 Record 0 Offset 0 (163840000 total bytes read)
Elapsed Seconds: 72: Data Rate: 2.16667MB/s
yorp.feral.com > tape_pattern_tester -v -b 32k -r 1000 -n 5 -f /dev/nsa1
.......Rewind Tape
........Write Pass
EOT at File 4 Record 1000 Offset 32768 (163840000 total bytes written)
Elapsed Seconds: 206; Data Rate: 0.757282MB/s
.......Rewind Tape
.........Read Pass
EOT at File 5 Record 0 Offset 0 (163840000 total bytes read)
Elapsed Seconds: 103: Data Rate: 1.51456MB/s
yorp.feral.com > 



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