[5302] in linux-scsi channel archive
Re: DAT trouble
daemon@ATHENA.MIT.EDU (Adrian Lawrence)
Sat Dec 5 18:07:54 1998
To: linux-scsi@vger.rutgers.edu
Date: Sat, 5 Dec 1998 11:38:57 +0000 (GMT)
In-Reply-To: <36680070.B4EDF1C3@estinc.com> from "Richard Fish" at Dec 4, 98 08:32:00 am
From: Adrian Lawrence <adrian.lawrence@computing-services.oxford.ac.uk>
> Jon Lewis wrote:
> >
> > On Thu, 3 Dec 1998, Richard Fish wrote:
> >
> > > Another test is to run a backup, turning off software and hardware
> > > compression with "mt -f /dev/st0 datcompression off". Your throughput
> > > to the drive should be ~366K/sec with DDS-II. With DDS1 you will get
> > > ~175K/sec.
> >
> > It doesn't seem to be that simple. Sony claims the 7000 can do 1.5MB/s.
> > In real life, I got 40MB/min, which is about twice the speed I used to get
> > from older Archive based DATs.
>
[...]
>
> A quick survey of DDS2 drive manufactures web sites indicates a wide
> range of claimed transfer rates -- from 366K/s native for a WangDAT up
> to the 788K/s for the Sony...
For what it is worth, I get transfer rates in excess of 1.3 MB/s to tape
with the unmodified st driver on a P2 with AH2940UW. That is data after
compression: measured by tape blocks/time on a tar transfer. This is an
NS20 drive rather than DAT, but shows that the scsi st thoughput is unlikely
to be the bottleneck? 2.0.36
ael
--
Adrian Lawrence.
adrian.lawrence@oucs.ox.ac.uk. or adrian.lawrence@comlab.ox.ac.uk
MicroProcessor Unit | Computing Laboratory,
13, Banbury Road, | Wolfson Building,
Oxford. OX2 6NN. | Parks Road, Oxford.
UK. | OX1 3QD. UK.
Voice: (+44)-1865-273274, Fax: (+44)-1865-273275
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