[Veritas-bu] Question regarding available tapes.

Yeah - text stuff is pretty squishy - it'll get down there - I've seen much
more than the average 2:1.  My database backups only get about 1.3:1 or so,
not very compressible.  

It varies a lot by data type.

...and, yes, it's the amount *on* the tape - but that's disk bytes sent to
that tape, not tape bytes occupied.  If you see 100G reported as being on
the tape, it may only be taking up 50GB of actual tape media.  Like I said,
the amount remaining, given compression, is very hard to calculate.

-M

-----Original Message-----
From: Piszcz, Justin [mailto:jpiszcz AT servervault DOT com]
Sent: Thursday, December 15, 2005 11:18 AM
To: Mark.Donaldson AT cexp DOT com; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Question regarding available tapes.


Interesting though, I use LTO2 which are 200/400GB, but with
compression, it ranges from 400-500gb on some tapes.

-----Original Message-----
From: Mark.Donaldson AT cexp DOT com [mailto:Mark.Donaldson AT cexp DOT com] 
Sent: Thursday, December 15, 2005 1:00 PM
To: Piszcz, Justin; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Question regarding available tapes.

bpmedialist will give you a count of how how many bytes are on the tape
(kbytes column):

> bpmedialist -U
Server Host = XXXXXXXXXXXXX

 id     rl  images   allocated        last updated      density  kbytes
restores
           vimages   expiration       last read         <------- STATUS
------->
------------------------------------------------------------------------
----
----
004526   3    310   08/21/2005 03:40  12/11/2005 06:36  hcart2
61698920
0
              MPX   01/11/2006 06:36        N/A

004696   3    874   11/20/2005 02:37  12/12/2005 02:33  hcart2
318870566
0
              MPX   01/12/2006 02:33        N/A

004801   4     32   11/15/2005 19:54  11/15/2005 19:55  hcart2
81122987
0
              MPX   01/16/2006 19:55        N/A

005165   6      6   06/15/2005 19:33  06/15/2005 19:33  hcart2
19992648
2
              MPX   06/15/2006 19:33  07/11/2005 15:52

005265   3   1874   06/10/2005 16:54  12/11/2005 06:01  hcart2
557969356
0
              MPX   01/11/2006 07:29        N/A

After that, you're starting to guess.  Because the amount of bytes per
tape
can vary by the compressibilty of the data, the total amount of bytes
actually stored on the tape can vary.  The closest you can do is
calculate
some sort of average compression ratio by looking at full tapes, then
estimate based on that for your non-full tapes. Personally, I'd do this
by
volume pool as my compressibility is going to vary a lot by data source.


HTH - M


-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Piszcz,
Justin
Sent: Thursday, December 15, 2005 10:40 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Question regarding available tapes.


Hello,
 
I can easily see how many scratch tapes, those that have not been
written to
yet.  However, I probably have several tapes that are currently not
fully
filled up, scratch tapes that had a few fragments written to it.  Is
there
anyway to determine how full the tapes are?
 
Justin.