*BSD News Article 78413


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From: migieger@luva.lb.bawue.de (Michael Giegerich)
Newsgroups: comp.unix.admin,comp.unix.questions,comp.unix.misc,comp.unix.solaris,comp.unix.bsd.bsdi.misc
Subject: Re: ideal parameters for backup tape
Date: 16 Sep 1996 20:13:37 +0200
Organization: BaWue-Net Ludwigsburg
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Message-ID: <51k5ch$hqm@luva.lb.bawue.de>
References: <323954B8.167EB0E7@innet.be> <51e1gk$cv2@agate.nbnet.nb.ca> <51ghpe$qh1@luva.lb.bawue.de> <51gugv$818@agate.nbnet.nb.ca>
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[... storage on 90 m DAT DDS ...]

>>Actually when used in a BSD/OS system you won't never
>>get 8 MB on your tape - I doubt you get 4 MB on the 
>>tape - as you will already have compressed files on
>>your disks and these won't get compressed any more
>>by the streamer.
>
> Umm. 8 meg? 4 meg? :)

You chose :-)
If you believe a compression ratio of 4:1 it's 8 GB
if you believe only 2:1 it's 2 GB...
As stated later I'm not believing anything and assume
1:1 though putting only 2 GB on the tape :-)

[...]

> Well, don't you have to tell dump the tape length in feet and its
>density so dump can calculate the tapes meggage? (Unix can be dumb
>sometimes.. They should just have a command that you TELL dump the #
>of megs :P)

You don't have to tell it the length.
You actually TELL dump how many bytes it can store on
the tape using parameter ``B''.

-- 
Michael Giegerich, E-Mail: migieger@luva.lb.bawue.de, Voice: +49 7144 39337