Clem,
You have made a rather curious
comment. You don’t have to delete the tape to get the space
returned. (My experience is with the NetApp VTL.) There are
settings on the VTL that you can set to allow for how long you keep a virtual
tape in the “shadow” pool once it has been “cloned” to
physical tape.
If you are not cloning to physical tape
and are just keeping images on virtual tape, then you would not be “deleting”
the tapes, you would be expiring images…just like Curtis said about the
DSU.
That’s one of the nice features of
the NetApp VTL. If you have the disk space, as long as you have cloned to
physical tape it will keep the virtual tapes around until the VTL needs to free
up space for newer backups. It does this for you automatically!
--stuart
From:
veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Clem Kruger
Sent: Saturday, September 22, 2007
2:33 AM
To: Curtis Preston;
VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Script
to label expired tapes in a VTL
Hi Curtis,
You have to delete the tape to get your space returned. This is the
real pain and cost
Clem.
-----Original Message-----
From: Curtis Preston [mailto:cpreston AT glasshouse DOT com]
Sent: 22 September 2007 11:15 AM
To: Clem Kruger; VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Script to label expired tapes in a VTL
And you don't get the space back on a DSU until you
expire the image.
So what? I also argue that what Steve is asking
for isn't necessary.
(I think he's MAKING it necessary by oversubscribing,
but that's not the
VTL's fault.)
Oversubscription aside, once his tapes are expired,
the space taken up
by those tapes is immediately available for
reuse. The next time the
tape gets written to, it will delete all pointers to
the space taken up
by that tape.
As to the VTL vs disk debate, I still think you should
bring in all disk
devices and let them duke it out before excluding an
entire category of
them. You're going to exclude a lot of really
good products if you just
"no VTLs."
Remember that saying "I don't want a VTL but I do
want de-dupe" means
that you're going to use NAS. While that will
meet a whole lot of needs
for a whole lot of people, there's also some really
big backups that
need a lot more than you can push over IP. For
those backups, you're
going to want a block transfer protocol (i.e. SCSI),
and for that,
you're currently going to be buying a VTL.
(Unless you're just going to
buy a non-deduped disk in which case I'd say you're REALLY
wasting your
money.)
---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On
Behalf Of Clem
Kruger
Sent: Saturday, September 22, 2007 4:24 AM
To: VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Script to label expired
tapes in a VTL
Hi Steve,
This is the downer on VTL's. You do not get your
"tape" space back
automatically. It is for these reasons I recommend
that one never go
VTL's. NetBackup 6.0 and 6.5 allow disk to disk
backups; the images are
easily replicated to an offsite facility.
The time for all "tape" has come and gone.
The de-duplication facility
in 6.5 makes life even easier. Why VTL's (which does
SCSI emulation)
when you and use disk which is faster and has more
protection?
Clem.
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On
Behalf Of swaltner
Sent: 21 September 2007 17:32 PM
To: VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Script to label expired tapes in
a VTL
We deployed a VTL last month, which has been working
very nicely. This
is in a NetBackup 5.1 environment with the VTL
attached to our Solaris
based master server as well as to our NAS server for
local NDMP backups.
One thing I'd like to do is over-subscribe on the
back-end storage, but
before I do that I'd like to automate the process of
freeing up the disk
space used in the VTL when a NetBackup tape is
expired. Just curious if
anyone has already written such a beast and would like
to share with me
as a starting point.
If not, I suspect I'll use the following logic:
- Every day (at noon??), query the robots defined in
the VTL and keep a
record of tapes that are allocated.
- When a tape goes from allocated to non-allocated
from one day to the
next, use a command like the following to erase the
tape's contents:
bplabel -erase -o -d dlt -m VTL123
This would write a small label at the beginning of the
virtual tape,
causing the VTL to drop all the other data that had
been stored on the
tape.
Any reason this wouldn't work? Any gotchas with
writing this script that
I should look out for?
Steve
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