Virtual Tape Capacity

[rdphill]

We have recently deployed Diligent's Virtual Tape Open v.1.4.

There are 61 cartridges defined and Commvault is successfully using the VTF library/drives. The issue is, no matter what size is defined for the tapes, Commvault always reports them as 39.99GB. I'm not sure if this is really an issue as it appears the full amount is being consumed when looking in VTF Manager.

It's just kind of annoying and my lead would like to know if it is something we can fix....

Thanks for any input on this.

 

[simple99]

rdphill,
sounds like a call to Commvault support is required, so they can have closer look at the system setup and identify any issues.

 

[rdphill]

Thanks...yeah called Commvault and they are saying they have no control over it. Commvault simply receive the information from the Virtual Tape Facility. Kind of turning into a "it's not us" from both Diligent and Commvault.

Funny thing is the correct amount appears to be used for the tapes even though the native capacity of the tapes is always 39.99GB no matter what size is actually defined in VTF Open.

If I ever get a conclusive answer I'll post it...
Thanks

 

[Chacalinc]

Funny thing is the correct amount appears to be used for the tapes even though the native capacity of the tapes is always 39.99GB no matter what size is actually defined in VTF Open.

do you mean that despite the CommVault states 39.99GB the real usage is larger than that? e.g. if the VTF-Open is configured with 400GB tapes, the real usage by CommVault is (aprox) 400GB?

Thanks!

Chacal, Inc.

 

[rdphill]

Correct.

There are 60 cartridges defined in Diligent VTF Open.

50 are the first original cartridges implemented last month as 40GB each.

When I right click/Properties a tape in CV and click the second tab it reports the native capacity to be 39.99GB.

Ok that looks about right for a 40GB tape. Those get about 140GB compressed before reaching physical end of media.

The last 10 were defined a few weeks back. I wanted fewer tapes with more capacity each so we carved out 1 TB of SAN space into 10 100GB virtual tapes for the same library.

CV picked up the tapes no problem. These 100GB tapes are storing about 340GB compressed so I feel that they are using all the available space to write data.

The only puzzling part is when looking at the native capacity of the 100Gb tapes CV still reports 39.99GB.

So the question is, where is CV getting this? Can it be adjusted or is it meaningless and can be ignored.

CV support says, we only present what is giving to us from the Virtual Tape Facility and of course Diligent says we are reporting correctly so it must be CV.....

Rick

 

[Chacalinc]

Rick, thanks for your response.

Have you tryed to use a 100GB virtual tape doing a backup with no compression? It is to test the real capacity used for the backup from CV.

Do you clone or destage the virtual tape to a real tape after the backup is done? (or some kind of destage/movement to real tape) if so, to what kind of tape? (LTO, DLT, other).

Thanks a lot for your information, it's very valuable.

Cheers,

Chacal, Inc.