[Veritas-bu] Tape capacity

2001-12-10 10:52:57
Subject: [Veritas-bu] Tape capacity
From: anthony.guzzi AT storability DOT com (anthony.guzzi AT storability DOT com)
Date: Mon, 10 Dec 2001 10:52:57 -0500

   I'm sure others will tell you this same things, but.........    A 
DLT4000 is a 20GB-nominal device using type IV tapes (which I'm assuming 
you're using).  The 40GB capacity is assuming 2:1 compression which means 
how much you get on the tape will depend on the nature of the data you're 
backing up.  Unless your data is very compressable, getting approx 40GB 
per tape would seem to meet expectations.

Question:   By 'something less than 40Gb', do mean high-30's (ie. close to 40, 
which is how I'm interpreting it) 
or something a lot less?

-- Tony Guzzi
Sr. Solutions Engineer, AssuredRestore team
Storability, Inc.
Southborough, MA 01772
The Leading Provider of Automated Storage Assurance for the Enterprise

Message: 1
To: Veritas BU <veritas-bu AT mailman.eng.auburn DOT edu>
Date: Sun, 09 Dec 2001 17:22:58 +0900
From: Noel Lindsay Hunt <nhunt AT lehman DOT com>
Subject: [Veritas-bu] Tape capacity

I am having big problems writing to a Quantum DLT4000.
This drive is attached to an Ultra 2 which was running a
set of dump scripts using ufsdump, writing to the `ultra'
compressed device, `/dev/rmt/0ubn', dumping roughly 41Gb,
well within the capacity of the compression device.

This machine has now become a media server, and the
storage unit is this drive, using the same device file,
but NetBackup is exiting after writing something less
than 40Gb. The bptm log file even shows it reads EOM from
the tape (unless I am sorely mistaken). I can't
understand what is happening. As far as I can see this
shouldn't happen. Has anyone any experience with this

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