Veritas-bu

[Veritas-bu] How to check the approx. available space on a tape?

2007-03-29 10:03:23
Subject: [Veritas-bu] How to check the approx. available space on a tape?
From: Patrick.Whelan at colt.net (Whelan, Patrick)
Date: Thu, 29 Mar 2007 15:03:23 +0100
Since no two tapes are exactly the same length, what is this going to tell you, 
even if you did find out where the EOT marker was? I suppose if your are really 
insistent on the length of tape (there always seems to be one every year), you 
could take one apart, measure it's length, try to determine where the EOT is, 
find the percentage of the tape up to that point and use this as a general rule 
for all other tapes. Of course to know for sure you are going to have to take 
apart all tapes and measure each one just to be sure. Having never actually 
tried this, I can only assume that winding the tape back in to the cartridge 
could be a real bear.

Regards, 

Patrick Whelan
NetBackup Specialist
Architect & Engineering
+44 20 7863 5243

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-----Original Message-----
From: veritas-bu-bounces at mailman.eng.auburn.edu [mailto:veritas-bu-bounces 
at mailman.eng.auburn.edu] On Behalf Of Alexander Skwar
Sent: 29 March 2007 14:52
To: veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] Howto check the approx. available space on a tape?

Martin, Jonathan (Contractor) <JMARTI05 at intersil.com> wrote:

> There's no way to tell exactly how much more data a single tape will
> hold, since anything better than 100GB (in your example) is compression
> and compression varies by file type.

Yes, I know. I'm not looking for an exact number. I don't know how
LTO tapes exactly work, but I suppose that the tape is written now
until a certain "position". If the tape is 609 meter long, it might be
written up to 550 meters, which would be about 90%. Or is that assumption
completely off?

Alexander Skwar

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