You may not be using software compression (client compression checkbox in
the GUI) but you may well be using hardware compression inherent in the
drive hardware itself.
If this is unix, then usually the option to use drive-based hardware
compression is part of the drive name. On my LTO drives, it's /dev/rmt/0cbn
when the "cbn" portion translates to "compressed, block mode (?),
no-rewind". Hardware compression is a good idea, very reliable, and a
preferable to client-side compression.
Your other tape that has 50 GB of images on it but is still full probably
contains expired images. The new images are appended to the end of the tape
and while there's 50 GB of valid images, there's probably 130GB of expired
images. When the valid images on the tape expire, then the tape is marked
as empty and reusable.
For your multi-retention tape, you can use the "bimmedia -mediaid <tapenum>"
command to display the valid images on that tape.
-M
-----Original Message-----
From: Dave Lowenstein [mailto:dlowenst AT mail.sdsu DOT edu]
Sent: Monday, November 24, 2003 11:30 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] How full are my tapes?
I feel like I'm getting incorrect information from available_media and
from getting reports from the gui on how much space is available on my
tapes.
I'm running 4.5 fp3 on solaris with an lto-1 autoloader with 9
tapes. These tapes hold 100GB uncompressed, and I'm not using compression
on any of my backups yet some of the output from available_media shows
well over 100gb on a tape. Tape 2771L1 says it has 247 gb if my math is
correct. That wouldn't even be possible if I was using compression.
I made the mistake of doing ALLOW_MULTIPLE_RETENTIONS_PER_TAPE before I
realized the ramifications, and now tape 2777L1 thinks it has multiple
retentions on it but I can't seem to find the offending image and move or
get rid of it. I think all the images on it are of the same retention
level.
Also, tape 2773L1 which claims to have 181GB on it really only has two
images that couldn't add up to more than 50GB, yet it says it's full.
Does anybody have a better idea than me as to what is going on here?
# available_media
media media robot robot robot side/ ret size status
ID type type # slot face level KBytes
----------------------------------------------------------------------------
DataStore pool
2778L1 HCART NONE - - - 8 38698848 ACTIVE
NetBackup pool
2770L1 HCART TLD 0 1 - 1 36070592 ACTIVE
2772L1 HCART TLD 0 3 - 6 46737984 ACTIVE
2774L1 HCART TLD 0 5 - 8 228178592
ACTIVE
2776L1 HCART TLD 0 7 - 4 117372480
ACTIVE
2777L1 HCART NONE - - - 3* 199232640
ACTIVE
2779L1 HCART TLD 0 9 - 0 34181664 ACTIVE
2771L1 HCART TLD 0 2 - 3 247119744
FULL
2773L1 HCART TLD 0 4 - 3 181521056
FULL
2775L1 HCART TLD 0 6 - 4 323690688
FULL
2780L1 HCART TLD 0 8 - 3 250214848
FULL
Dave Lowenstein
Analyst/Programmer
Instructional Technology Services
San Diego State University
(619)594-0270
http://www-rohan.sdsu.edu/dept/its
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