Path: utzoo!utgpu!watserv1!watmath!att!cbnewsk!rsb1
From: rsb1@cbnewsk.att.com (richard.s.brown)
Newsgroups: comp.unix.wizards
Subject: Re: Dumping to an exabyte tape drive
Summary: 'dump' values for Exabyte drives
Message-ID: <1990Sep4.170228.16597@cbnewsk.att.com>
Date: 4 Sep 90 17:02:28 GMT
References: <1990Aug29.143657.20588@siesoft.co.uk>
Organization: AT&T Bell Laboratories
Lines: 27

In article <1990Aug29.143657.20588@siesoft.co.uk>, duncan@siesoft.co.uk (Duncan McEwan) writes:

> I have just started using an exabyte tape drive to do dumps of our file
> systems.  Could someone please tell me the appropriate values to give
> to dump (tape length, density, inter-record gap (is this relevent for this
> encoding format?)) to allow dump to fully utilise each tape.
> 
> For now I am kludging it using a bogus tape length of ~200000 feet (estimated
> by knowing that dump will write approx 64MB onto a 5400 ft streamer cartridge),
> but I would like to know the correct values.  In particular, how much *can*
> you fit on a single 90 minute tape, and how long are the tapes?

	We use 120 min tapes. We bought our drives from Perfect Byte, Inc.
	in Omaha, Nebraska. The documentation we received was remarkably
	good (and concise!) Here are the suggested values for 'dump':

		Blocking factor:	126

		Density:		54000 (bpi!!!)

		Length:			6000 (ft.)

	I hope this helps!

				Rich Brown
				AT&T Network Systems
				rsb@vogon.att.com