Re: StoreOnce configured as VTL question (251 Views)
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Honored Contributor
jason_lee
Posts: 772
Registered: ‎10-25-2006
Message 1 of 4 (307 Views)

StoreOnce configured as VTL question

Hi,

 Here's our environment:

 

1) DP 8.1 CM (RHEL 6.2)

2) Attached with StoreOnce 4500  with 16TB storage

 

The HP engineer created a VTL from the StoreOnce:

-  1 Robotic

-  10 Drives

-  96 slots

-  Ultrium-4 tapes 400GB

 

My question: what's the limit of the number of (virtual) tapes that I can format?

is it  40 (tapes) X 400GB = 16TB ? Can I format 80(tapes) or more?

 

 

Honored Contributor
jason_lee
Posts: 772
Registered: ‎10-25-2006
Message 2 of 4 (268 Views)

Re: StoreOnce configured as VTL question

Hi

  DP expert/gurus/anyone,

  Have you use other VTL before?

  Can you share your experience on this (formatting tapes that exceed the Storage capacity)?

 

 

Honored Contributor
André Beck
Posts: 515
Registered: ‎06-23-2005
Message 3 of 4 (251 Views)

Re: StoreOnce configured as VTL question

[ Edited ]

jason_lee wrote:

The HP engineer created a VTL from the StoreOnce:

-  1 Robotic

-  10 Drives

-  96 slots

-  Ultrium-4 tapes 400GB

My question: what's the limit of the number of (virtual) tapes that I can format?


First off, that's a strange choice IMO. Why? Because the answer to your question is: In a VTL you can have exactly as many media as there are slots configured. The VTL has no way of vaulting/unvaulting them by some automatism, so it simply is "you get what you have slots for". In that sense, unless you have a backup software with licensing considerations, the only type of library you want is D2DBS Generic, and the number of slots you want is maxed out - which means 1024. The number of drives is another thing, it depends on the parallelism you want and the number of backup specs you want to have directed to different drives, so they wont collide and queue, plus maybe surplus drives for copying. I found 32 to be a good number, but that entirely depends on your environment. And media type is of second consideration as well, as you never want to append to virtual media on a StoreOnce VTL.

 

Caution: DO NOT FORMAT THE TAPES. Make sure all the media in the VTL is detected as Blank (Scan all slots, that should do it). Use a Pool with allocation strategy Loose, Non Appendable, and set the global option InitOnLoosePolicy to 1. This is the only way for the media pool to do somewhat correct recycle of expired media, which in turn is essential for freeing the media on the appliance and allow it to housekeep the litter away. Background: If you format all the media, DP will write to newly formatted media before ever starting to overwrite recycled media. To prevent this, the pool of actually formatted media should be kept as small as possible, but should be able to spill into blank tapes when data amount increases. The hard part is to shrink the pool again when the data amount decreases (or you reduce protection), but that's another story (oh if HP would only allow us to use "Erase" on VTL media, or for that matter, any tape media)...

 

HTH,

Andre.

Honored Contributor
jason_lee
Posts: 772
Registered: ‎10-25-2006
Message 4 of 4 (243 Views)

Re: StoreOnce configured as VTL question

Thanks Andre, now I understand more about how to use StoreOnce as VTL

 

 

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