Question Backup Size Vs Database Size

[Mike]

Hi,

I have some doubt please clarify!

1. My database size is 100 GB,now i took online backup (progress 11.3)of that database.
now backup size is 75 GB.

Q:- why backup size is lesser than database size?

Please Clarify !

with regards
Mike

 

[TomBascom]

What specific backup command did you run?

Generally you would get this sort of a result because allocated space is not the same as space used. In a simple case - you might have a fixed length storage area of 100GB but you have only actually used 75GB of the space. There is no need to backup the unused portion.

 

[Cringer]

Tricky to say for certain, but one guess would be that you have fixed database extents that have empty space in them that don't need to be

 

[joey.jeremiah]

plus if you compress your backups (with or without -com) the compression ratio is huge (if i'm not mistaken, around 1/7)! since most of it is text.

you may want to check the backsys/ directory in the standard libraries project at the oehive.org.