Date: Tue, 16 Mar 1999 21:55:07 +1000 From: Greg Black <gjb@comkey.com.au> To: robert <robert@mhi-tx.com> Cc: freebsd list <freebsd-questions@FreeBSD.ORG> Subject: Re: dump problem Message-ID: <19990316115507.27451.qmail@alpha.comkey.com.au> In-Reply-To: <36ED5B73.8E5101CD@mhi-tx.com> of Mon, 15 Mar 1999 13:11:48 CST References: <36ED5B73.8E5101CD@mhi-tx.com>
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> I am having a problem with dump or my tape drive.
> I have a partition 2gig /usr that I am trying to backup onto an hp dat
> drive with a 2gb tape (4gb) compressed. however near the end of the
> backup about 77% I get a tape write error. and I am asked if I want to
> restart. if I say yes this continues over and over at 77% otherwise it
> aborts and I dont get all of my backup.
> I have a feeling that it is at the end of the tape and instead of the
> drive giving a end of medium it just spits out an error, therefore not
> giving me the chance to put in another tape. I tried using -s feet but
> my tapes say 90meter wich is about 968 feet but that says I will need
> like 156 tapes to do this backup which can't be right.
You probably want to first find out a bit more about what you
can do with that drive and the tapes you're using. Compression
is often not featured on drives that handle 90 metre tapes, so
you could first test for that with something like this:
dd if=/dev/zero of=/dev/rst0 bs=64k
Obviously, replace the /dev/rst0 with whatever is appropriate
for your drive. If the drive doesn't do compression, it'll
probably accept around 1.8 GB of data (about average for "2 GB"
tapes); if it does compression, it'll take heaps since /dev/zero
compresses rather well :-) The capacity indicated by this
method is not any indicator of the real compressed capacity of
the tape, since real data doesn't often consist of billions of
zero bits. Once we know how this goes, the next questions will
become more evident.
--
Greg Black <gjb@acm.org>
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