Re: RMAN - size of backup set

Andy Kent wrote:
> We have an old 8i system which does disk-to-disk RMAN backups. The
> database comprises 25GB of datafiles of which only 15GB of the space is
> actually allocated to blocks. Yet the level 0 backup sets run to 21GB
> (which happens to be almost identical to the total size of datafiles
> minus TEMP and RBS - don't know if this is relevant). Any pointers as
> to why? I thought RMAN only backed up actual used block - what do we
> have to do to get the backup down to this size?
>
> Our scripts set limits of 1,500,000kB on piece sizes, but the resultant
> files are not in multiples of that figure.
>
> It's 8.1.7 on Solaris 5.8.
>
> Thanks
>
> Andy

RMAN skips blocks that have never been touched. Once a block has been touched, it will go to backup, even if it is empty.

-- 
Sybrand Bakker
Senior Oracle DBA