Media tapes retention

[ankushkalra]

Hi,

I am using veritas netbackup 6.5.6 in our envirement for taking backup of unix  and windows boxes.

I have created two different policy with different retention .One sechdule has 7 days retention and other sechdule has one Month retention.

I have noticed one strage thing.As per my understanding,Backups of both these sechdule data cannot be written to one tape.I have to provide two seprate tape one for each sechdule for backup to happen successfullly.

I have also notticed that tape which has data written witth 7 days policy retention cannot write data of policy which has 1 month retention ontoi tself.I have to provide seprate tape for it which is wasting my tape.

My question is as below.

1.is this correct or i am doing something wrong

2.what can be done if i want to write both policues data in a single tape.

Thanks

[watsons]

By default, media tapes are not shared by "multiple retention"

To enable that, go to master server host properties ->  Media -> Check the "allow multiple retentions per media".

[Marianne]

 Writing different retentions to one tape may save you media in the short term, but will cause more media usage in the long run.

Bear in mind that space occupied by expired daily images mixed with unexpired weekly images on the same tape cannot be overwritten . 

Media can either be appended to or else overwritten from scratch when all images have expired .

Have a look at this excellent blog:

https://www-secure.symantec.com/connect/blogs/understanding-how-netbackup-writes-tape

[a_la_carte · Accepted solution]

It all depands on you as a Backup Admin or on your customer how both of you wish to utilize your tapes or save money on them.

The best practices say that multiple retentions on the same media should be avoided.

Also, if you have different media servers in your environment, then media-sharing can also be enabled for optimum utilization of tapes across the environment. 

[ankushkalra]

Thanks all for the responce