Re: RMAN backup size is almost bigger twice than all of tablespace used size?

Hello Quanwen,
I guess you are referring to RMAN's unused block compression feature.

Do you meet all requirements to make unused block compression kick in - see here "8.3.2.1 About Unused Block Compression": https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/rman-backup-concepts.html#GUID-74FF41AF-D1EE-4DB1-AC0D-56FC83CAA91D

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Website: www.soocs.de
Twitter: _at_OracleSK

> Quanwen Zhao <quanwenzhao_at_gmail.com> hat am 15.11.2023 15:14 CET geschrieben:
>
> Hello everyone!
>
> Recenty I've notice that there has oracle product system with 19.13, RMAN backup size is almost bigger twice than all of tablespace used size?
>
> Such as, all of tablespace used size is 600 GB and total size is 2500 GB, RMAN backup size (generated backup sets) is 1300 GB.
>
> Generally speaking, RMAN backup size is almost equal to all of tablespace used size.
>
> Firstly I suspect oracle recyclebin has occupied the massive data but the parameter recyclebin is off.
>
> Now I have to infer business tablespace has produced plenty of table fragments or HWM (High Water Mask) or discontinuous free data blocks.
>
> How to troubleshoot it for me? Any suggestion would be very appreciated!
>
> Best Regards
> Quanwen Zhao

--
http://www.freelists.org/webpage/oracle-l