Forum Discussion

manatee's avatar
manatee
Level 6
11 years ago

pool creation - on retention period

NBU 7.5.05

first time creating a pool. i came across the question of "retention period". if i select "infinity", would that mean:

  1. once data has been deduplicated to one of the media in the pool, said media cannot be use to append more data OR
  2. data can still be appended until the media is full but existing data will never be overwritten

regards,

rino

7.5
Backing Up
Backup and Recovery
NetBackup
Tip-How to
Windows Server (2003-2008)
  • watsons's avatar
    watsons
    11 years ago

    retention period is designed for backup image, not the media tape.

    So what setting to "infinity" means is that the image written onto the tape will never expire, so it will consume your media tape capacity. 

    If a tape is FULL with many images of infinity retentiion period, the tape will never get reused until you expire some images inside.

    If a tape is half-full with images of infinity retentiion period, you can still write some more images onto it until it becomes full.

    There is a separate way to set media tape "expiration", on the media level via Netbackup, it is different from what the retention period means.

  • watsons's avatar
    watsons
    Level 6
    11 years ago

    retention period is designed for backup image, not the media tape.

    So what setting to "infinity" means is that the image written onto the tape will never expire, so it will consume your media tape capacity. 

    If a tape is FULL with many images of infinity retentiion period, the tape will never get reused until you expire some images inside.

    If a tape is half-full with images of infinity retentiion period, you can still write some more images onto it until it becomes full.

    There is a separate way to set media tape "expiration", on the media level via Netbackup, it is different from what the retention period means.

  • Marianne's avatar
    Marianne
    Level 6
    11 years ago

    Think twice before you select 'Infinity'.

    Do you really have a requirement for 'Infinity' retention or are you selecting this retention because NBU does not have a built-in 5- or 7-year retention?

    If you did not know this - Retention levels can be customized in Host Properties.

  • Stumpr2's avatar
    Stumpr2
    Level 6
    11 years ago

    Expiring images on a tape does not necessarily create room on the tape for more images. NetBackup will only append images to an existing tape. Only by expiring the very last image on the tape can you make space available for reuse. Not much to gain there.

    Always try to minimize retention period. In the US if you have data on a tape that may pertain to a litigation then you may be legally bound to restore the data.

    Infinite retention can cause headaches if the data is not hydrated when new tape drives or backup solutions are entered into the environment. You may think you have data BUT can you restore it?

  • manatee's avatar
    manatee
    Level 6
    11 years ago

    i specifically chose "Infinity" based on finance requirements.

    but now that you mentioned that retention levels can be customized, how can i do that please?

  • manatee's avatar
    manatee
    Level 6
    11 years ago

    the thing is, finance have no policy on up to how many years to keep data. so we have to just archive them for an indefinite amount of time. we don't want to lessen retention period then 5 years from now found out that we can't restore because the image has expired.