Veritas-bu

Re: [Veritas-bu] Duplication question

2009-12-08 10:48:20
Subject: Re: [Veritas-bu] Duplication question
From: Heathe Kyle Yeakley <hkyeakley AT gmail DOT com>
To: Ed Wilts <ewilts AT ewilts DOT org>
Date: Tue, 08 Dec 2009 09:48:07 -0600
Let me explain *why* I'm trying to do this and maybe someone will have a different approach to solve the same problem.

I'm trying to deploy a NetApp Virtual Tape Library. I have three objectives for the deployment:

* My RPO is between 24 and 48 hours. I vault every weekday to get last night's tapes out.
* I'd like to shrink my backup window. Therefore I'd like to present dozens of virtual drives to NetBackup so that I can perform multiple backups concurrently.
* I'd like to utilize my tapes as best as possible.

When I originally rolled out the VTL, I presented 80 drives to NetBackup. This was on a Friday. When I came in Monday all my backups had completed successfully. I ran Vault and the eject phase triggered the Direct Tape Creation on the VTL. I watched all of this go by quite smoothly. But then I got to counting how many tapes had been created and noticed it was 30% - 40% more tapes than I normally write to over the weekend. I thought about it for a bit and realized that what had happened is with 80 drives, NetBackup grabbed 80 scratch tapes and therefore didn't reuse any tapes. So I was ejecting 80 tapes that were anywhere from 15% - 30% full.

I've rolled the VTL back into development. In my original configuration, I met the 24-48 hour RPO and I shrank my backup window, but at the expense of burning through a lot of tapes. I e-mailed Symantec to ask if there is a setting in Vault where NetBackup will leave a tape in the library if it's under X% full. I'm told there is not such feature, but that it gets requested frequently.

On a side note, if you want that feature, I've submitted a suggestion on the NetBackup suggestion page. Please vote:

http://www.symantec.com/connect/idea/tape-utilization-criteria-netbackup-vault

Anyway, so I took the VTL back to the drawing board. My second thought was to just present 12 drives to NetBackup since I'm making due with 12 physical drives right now. Only presenting 12 drives and thus only backing up 12 clients at a time would reuse tapes and let me use my media more efficiently. I could vault every morning to meet my RPO, but 12 drives really doesn't buy me anything in the backup window.

My next thought was to leave my dozens of drives presented to Netbackup and just change my vault window from:
30 days ago to 18 hours ago

to

30 days ago to 5 days ago.

This would leave my tapes in the VTL for a few days to build up some images on them. So I'm making good use of my media and I've shrunk my backup window, but I'm putting my RPO at risk. If  a fire or something destroyed my datacenter, I've now lost a week's worth of data instead of 24-48 hours worth.

So now my current thought goes something like this:

1) Have two virtual libraries on my VTL.
        - One library that does not employ DTC and has completely made up barcodes (fred001, fred002... whatever). This library has dozens of drives. We'll call this Vlib-A
        - One library has Direct Tape Creation enabled and has virtual tapes with a one-to-one relationship to the actual labels on the physical tapes in my physical library. This library only has like 12 - 20 drives. We'll call this Vlib-B.         

2) On Vlib-A, present dozens of drives to NetBackup and perform all my backups. (This shrinks my backup window).

3) In the morning, duplicate all of last night's backups from Vlib-A to Vlib-B. I've never used the Duplication feature in Vault, but I am *assuming* that if I've got a library of say, 50 drives trying to duplicate all of it's images to a library with say, 12 drives, that you end up with more images per tapes on the receiving library. Once I duplicate all my images from Vlib-A to Vlib-B, I'll use vault to eject all the volumes in Vlib-B. The NetApp VTL will receive the eject request and begin writing the contents of the virtual tapes out to physical tapes.

4) But now I have all these original images on Vlib-A that have been duplicated and written to tapes on Vlib-B. If there was a way I could erase successfully copied images as they are duplicated from Vlib-A to Vlib-B, I could have a sort of "static" pool of tapes in Vlib-A that I'm writing to every night, then duplicating off of every morning and then recycling the tapes again for the next night's backups.

This configuration (while WAAAAAAAAAAAAAAAAAAYYYYYYYYYYYYYYYYYYYYYYYYYYYY convoluted) would meet all three of my VTL objectives. But my concern is that there's no way to configure NetBackup to duplicate an image from TapeA to TapeB and then automatically expire the images on TapeA so that TapeA is reused again tonight. I'm afraid I'd have to come in and manually expire all the images by hand using bpexpdate after ensuring that the images were successfully copied to Vlib-B.

Anyway, that's what I'm trying to do. I've come up with half a dozen ways I can have 2 out of 3 things on my list of objectives, but I can't figure out how to have all three.

Thoughts?

Thanks guys.

- Heathe Kyle Yeakley

On 12/08/2009 08:50 AM, Ed Wilts wrote:
On Tue, Dec 8, 2009 at 8:17 AM, Heathe Kyle Yeakley <hkyeakley AT gmail DOT com> wrote:

    I'm not sure if this is possible, but is NetBackup Vault capable of:

* taking a backup image on tape ABC123
* duplicating the image to some other volume (say ABC124)
* promoting the copy on ABC124 to primary
* automatically deleting the original backup on ABC123 so that my only
copy is the primary copy on ABC124

??

I know how to do the first three bullet points in Vault. It's that 4th
one that I'm stumped on. I don't even know if it's possible.

Just expire the images that are on ABC123 using bpexpdate -copy

The key thing to remember is that NetBackup doesn't like to manipulate tapes - it likes to manipulate images.

Ed Wilts, RHCE, BCFP, BCSD, SCSP, SCSE
ewilts AT ewilts DOT org
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