Compression

[Trina]

Hi Everyone

I am running NBU6.0 MP3 under solaris 9 and have a query regarding compression.

We have several policies which backup to a disk storage unit and then that storage unit is swept off to tape.  I have a question regarding the hardware compression that i should be getting.  Our tape silo is an LTO2 with two drives and we are using 400GB LTO 2 tapes that should have a compression of 2 to 1, however for about 400 to 500 GB of data in the dsu we are using up to 5 tapes.  I am aware that i have the disk storage unit running to two drives but i would not expect it to use more than 2 tapes or 3 tapes at a push.

Has anyone else had this sort of issue and if so what are the recommended solution/s.

Thanks in advance

Regards Trina

[Stumpr2]

Do you have compression checked in the policy?

[Trina]

Hi Bob

No we do not have compression within the policies turned on.

Regards Trina

[Stumpr2]

Are there different retentions involved?

[Trina]

Hi Bob

Yes there are - but we are only loading tapes that have the "available" status so i would not have thought that the different retentions would apply - however i am not an expert (obviously)

Cheers Trina

[Stumpr2]

By default, different retentions cannot share a tape.

[Trina]

Hi Bob

Thanks - so i can just apply this setting - Host Properties - Master Servers - Media and restart netbackup and things should work as i initially expected.

Cheers Trina

[Stumpr2]

I don't recommend enabling "Allow multiple retentions per media" unless you are aware of the consequences. It sould only be used in small installations where tapedrives are sparse.

[Trina]

ok can you point me to any documentation on this

[Stumpr2]

The good =  lot of images on a tape and being able to better fill a tape

The bad = it takes longer for the tape to become available for reuse.

See this thread:

https://forums.symantec.com/syment/board/message?board.id=21&message.id=18403

Message Edited by Stumpr on 04-02-2008 08:13 PM

[Trina]

Thanks Bob - once again you are sharing your wealth of knowledge - which is much appreciated.

I have changed all of my policies which use this storage unit to be the same and will monitor what happens over night

[Stumpr2]

you're welcome. let me know how it fares.

[Trina]

Hi Bob

The tape backups are now only using 2-3 media, which is what i wanted to achieve.

Thanks again

Regards Trina

[Stumpr2]

ok