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LTO 3 Virtual Tape with maximum size 200GB

Created: 08 Nov 2010 • Updated: 15 Nov 2010 | 10 comments
This issue has been solved. See solution.

Is it any issue/problem for netbackup to backup to LTO 3 Virtual tape, but on VTL we create maximum size = 200GB for LTO3 Virtual Tape?

Why we set the size max 200GB for the virtual tape on our VTL because we implemented VTL compression (1:3 ratio).

And the requirement for tape migration to datadomain VTL system which is the data to be migrated from source VTL to target VTL cannot more than 800GB.

Any suggestion ?? Thank you.

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Rajesh_s's picture

Which VTL are you using ?....

As per my knowledge you can create tape at any size . While creating tapes you can create media size as per you requirement . Suppose if you have 1 TB of storage space and if you create 10 medias then it will be 100 GB per cartridge size and the same if you create 5 medias then it will be 200 GB per tape.

J.S. Darman Tuah Saragih's picture

We use EMC DL4000 and we can create tape at any sizes.

if we create LTO3 (400GB) for media type but the max size max 200GB on VTL/per virtual media, is it any issue for netbackup?


Deepak G's picture

Since you use VTL tape and drives it doesnt matter.

Rajesh_s's picture

There is no issue on the Netbackup front . Since physical drives comes in different capacity like LTO-1 100/200 GB , LTO-2 200/400 GB due to this limitation you need to use the same capacity tapes but for Virtual you can use as per your requirement .

yes you can use 200 GB or 150 GB or more tape size.

faridux's picture

For my part I use an HP VTL, it starts its deduplication once the virtual tape is full,

You may have to check this before setting the virtual tape size (I do not know the deduplication process in EMC VTL)

For info we have choosen 150GB for the cartridge size

Zahid.Haseeb's picture

It may help you.

Using Virtual Tape Libraries with Veritas NetBackup™ Software

Any comment will be appreciated. Mark as Solution if your query is resolved
Thanks in Advance
Zahid Haseeb

Nicolai's picture

The over subscription issue where a virtual cartridge can't fit on a physical tape is well known. Some vendors claim to use same compression algorithm code as the LTO tape drive thereby guaranteeing a 1:1 relationship. Other vendors take another approach and here you need to ensure the 1:1 relationship by by making the virtual tape smaller. This is no problem from a technical perspective. Netbackup will write data to a tape until the drive return a "EOM" - End of Media. If this message is returned at 200GB 400GB or 1600GB - Netbackup don't care.

From a cost perspective you need to keep in mind how much tape capacity you loose by under subscribing physical tapes.

Assumption is the mother of all mess ups.

If this post answered your'e qustion -  Please mark as a soloution.

AAlmroth's picture

LAst time I worked with EMC EDL (well back in 2008 mind you), the recommendation from the EMC consultants was to use 1:1 capacity - 20%...

Wow, they didn't even expect 1.4-2.0:1, but also undersubscribe the 1:1 with 20%... What a waste of physical tape if you use the builtin copy out function.

Much better then, and if you buy EMC you have the money, to go for the media option (NBU media server in the EDL), and have NBU to vault to physical tape, and use up the tapes, and not just copy out the VTL tapes to corresponding phys tapes.

Also, with the NBU option, you have full visibility in one tool where your backup copies are.



Things may have changes the past 2 years, I don't know, I don't use VTLs anymore, why add a completely useless abstraction to disks? Use backup to disk strategies instead, be it BasicDisk or de-dup disk.

Marianne's picture

Extract from NBU Device Compatibility List:

9. NetBackup NDMP Direct Copy with VTL or an embedded NetBackup media server (e.g., EMC DL4000) may be used to copy backup images (not media) from the VTL directly to physical tape or a 2nd VTL.

Copying virtual media to physical media or a 2nd virtual media is not supported by Symantec; any support for this must come from the VTL vendor providing the capability.

If the VTL copies virtual media to physical media (or a 2nd VTL), NetBackup is not aware of the physical media or 2nd virtual media and may not be able to recover that data directly from it.

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links