Retention Period Question

[steven_man]

 The backup schedule as follow:

Sunday (Full Backup) , Monday - Friday  (Incremental Backup). Assume the first Full backup job is star at is 12:00 AM at 1 Jan (Sun) . The complete time is 2:00 AM  at 1 Jan (Sun). Then incremental backup is start at 12:00 AM and end at 1:00 AM every Monday to Friday.

All backup jobs configure to backup files to local disk storage. The retension policy is 2 weeks. 

Withins two weeks, I can keep 2 sets of Full Backup and 10 sets of Incremental Backup.

The two questions I want to know:

1) After two weeks (15 Jan, Sun), the last Full backup set should be expired at 2:00 AM. Am I right? 

2) When this Full backup set is expired, will it release disk space immediately? Because 5 x incremental backup are relied on this Full Backup to restore.

Is it necessary to wait for more than 5 days (20 Jan, Fri)  to expire Full backup set and then free up the disk space occuiped by this Full Backup Set?

This information above can help to caculation the size of local storage.

[Colin_Weaver]

You haven't defined your BE version

2010 R3 and earlier use media sets as such the disk media will become overwritable at the end of the overwrite protection period and eventually be overwritten at the start of another backup job. There is no protection for incremental sets being dependent on the full.

2012 uses DLM (unless RDX disk is involved) and DLM will not let a full set be reclaimed(deleted) unless all the dependent incremantal and differential sets can also be reclaimed (so is based on the retention date/time of the last incremental.. However the process to look for reclaimable media and to delete it happens in the background at set intervals (not an immediate process).

DLM will also not let the last copy of a resource be reclaimed, although we are looking at this perhaps being a customizable setting in the future.

EDIT: More info on DLM here 

https://www-secure.symantec.com/connect/blogs/data-lifecycle-management-be-2012  

for more info on media sets see the article Craig mentions below.

[CraigV]

Hi Steven,

The link below will assist you with understanding retention in BE:

http://www.symantec.com/docs/TECH5459

Thanks!

[steven_man]

The version of my Backup Exec server is 2012

[Colin_Weaver]

In that case - my comments about DLM (as long as standard disk storage) apply - data will only be reclaimed, when certain conditions (which include the retention time and the retention time of any dependent sets are met) . Data that can be reclaimed is deleted by a regular background process, so within a few hours of the expiry of all applicable retention times as the backround process runs on a repetitve schedule and not all the time.

You should rewad the DLM blog I linked in my first post.

[pkh · Accepted solution]

2) When this Full backup set is expired, will it release disk space immediately?

No.  Assuming this full backup is taken on 1 Jan (Sun)

1) Even though the full backup has expired, the incremental backups taken on 2 - 6 Jan has not expired and are dependent on it for a restore.  It is only after the last incremental backup taken on 6 Jan has expired, then the entire chain from 1 Jan to 6 Jan is eligible for grooming

2) Even when a media set is eligible for grooming, it would not be deleted and the disk space freed until the next grooming cycle.  The data is groomed every 4 hours or when there is a low disk space condition.