Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!uunet!mcsun!unido!wrkof!dksoft!dirk
From: dirk@dksoft.incom.de (Dirk Koeppen)
Newsgroups: comp.unix.i386
Subject: Re: Tape backup
Message-ID: <580@dksoft.incom.de>
Date: 16 Nov 89 10:42:49 GMT
References: <991@dialogic.UUCP> <[255ff79a:153.1]comp.unix.i386;1@nstar.UUCP>
Organization: dksoft , EDV-Beratung , FRG-6050 Offenbach
Lines: 36

Dan Rich (drich@dialogic.UUCP) writes:
> I am really interested in DAT, but I can't find any DAT vendors that
> support UNIX.

I am using a GIGATAPE DAT-tape with 1,2G and SCSI Bus. They have drivers
for nearly all UNIX systems available. They also told me that it runs
with the SCSI version of XENIX or SCO-UNIX. I wrote a driver for the
386/ix OS due the ISC SCSI-tape driver can not handle variable block
sized devices.

Transfer rates are about 120-140 KB/sec. using finc or any other
block-based backup tools. Do not believe in transfer-rates above this,
most of the vendors are telling you the maximum transfer rate possible
with the DAT drive not with the embedded SCSI controller. 

It is also very important to have a fast disk drive and a large buffer
on the DAT-tape device. There is no need for transfer rates above 90 KB/sec.
due backup programs like cpio or tar can not give the constant transfer rate
which is need for the DAT or V8 tapes. If I use cpio for backup the transfer
rate falls as low as 40-70 KB/sec. due the tape goes into heavy start and stop
operations when it reaches directories like /dev/, /usr/include or the news
spool directory.

For Information:

GIGATAPE Systeme fuer Datensicherung GmbH
Benzstr. 28
D-8039 Puchheim
West Germany

Tel. 049 89 80 7002

They have several offices in the States and Europe too.

cu,
dirk@incom.de