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From: john@pacer.apana.org.au (John Saunders)
Newsgroups: comp.unix.bsd.freebsd.misc,comp.os.linux.hardware
Subject: Re: Tape backup speed FreeBSD v. Linux
Followup-To: comp.unix.bsd.freebsd.misc,comp.os.linux.hardware
Date: 7 Nov 1995 11:33:05 GMT
Organization: Pacer - Linux box at home
Lines: 22
Distribution: world
Message-ID: <47ng5h$4ln@pacer.apana.org.au>
References: <1995Oct30.090118.28117@state.systems.sa.gov.au>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:8261 comp.os.linux.hardware:20335
chdemgt@state.systems.sa.gov.au wrote:
>
> Claimed by Tandberg in the spec: 12/18 MB/min
> FreeBSD 951020 SNAP: 9.1 MB/min
> Linux 1.2.x (forget exactly): 15.4 MB/min
>
> The something was wrong could be detected at once by ear. On FreeBSD the tape
> seems to run forward for 1.5 sec and then back for 1.5 sec. This continues
> without intermission during the backup. On Linux the tape seems to run
> forwards for long periods of time, very occasionally reversing once.
It seems as though FreeBSD can't provide the drive with data fast enough to
keep it streaming. So the drive stops and must backup in preperation for the
next lot of data it receives.
If you are using "tar" then try setting the blocking factor (-b option) to
some larger value (e.g. 64 or 128). This seems to help sometimes.
-- . +------------------------------------------------------------+
,--_|\ | John Saunders - (Home) john@pacer.apana.org.au |
/ Oz \ | - (Work) johns@rd.scitec.com.au |
\_,--\_/ | "Mmmmmmmm beer..." - Homer Simpson |
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