Hi Stuart,

 

In my experience we had to as the “DISK SPACE” was still in use!

 

 

 

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

 

 

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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