Incremental Backups in RMAN

[Chucks_k]

Hi all,

I was just wondering using about incremental backup strategy with RMAN. What is the effect of doing an incremenal backup level 0 every day? Does it mean that whole db will be backep daily or does it mean only changed blocks are being backed up?. Reason i ask is that i have been noticing that our backup sizes have been going down and was wondering if this has anything to do with it!

Thanks in advance,
Chucks

[marist89]

Level 0 = Full backup.

Level 1 = Incremental backup.

[Chucks_k]

Thanks for that. So that means taking a full backup would mean the size of backup increasing marginally, so i am now wondering why the backups vary in size i.e it was 12G last night and 25G last week?

[marist89]

All RMAN backups backup blocks that have been used at some point. Blockes never used are not backed up. For example, you have a table that takes up 1000 blocks. You then truncate this table and you have 1000 blocks that have been used, but are empty. Logically, you would think that your backup would skip those empty blocks, but it doesn't. Those blocks continue to be backed up along with blocks that contain data.

I am guessing you are running into a scenario where you had a bunch of empty blocks being backed up and something happened in your DB (drop tablespace, resize datafile down, etc.) that got rid of those empty blocks.

[Latyr]

Originally posted by Chucks_k
What is the effect of doing an incremenal backup level 0 every day? Does it mean that whole db will be backep daily or does it mean only changed blocks are being backed up?.
Chucks [/B]

The only difference between a full backup and a Level 0 Inc backup is that Level 0 Inc backup can be use as a reference for higher level inc backup whereas full backup can not.

Latyr