why is there a difference of the data backup between Full Copy-Only and Full Backup - entire database

[ramy_shaker]

Dears ,

I configure a backup job to backup SQL 2008 database using Full Copy-Only , software comression and sql cpmoress  it takes about 160 GB

another backup job with the same selection list  using Full Backup - entire database  , software comression and sql compress it takes about 78 GB

why is there  a difference of the data backup between Full Copy-Only  and Full Backup - entire database

[pkh]

Full Copy-Only backs up the database, but does not disrupt any full and differential database and/or log backup sequence.

[Twinkle]

YOu may refer http://msdn.microsoft.com/en-us/library/ms191495.aspx for more detail.

[ramy_shaker]

Why the backup size is changed between them ?

one of them is 78 GB and the other is 160 GB

[pkh]

Is there any size difference if you do not use either the SQL or software compression? That is, no compression at all.  When you compress data which is already compressed, you might end up with more data than you have started with.

[ramy_shaker]

I configure software compression and sql compression on the both method. but there is a diffrence in size

[pkh · Accepted solution]

To eliminate the effects of compression, you should compare the uncompressed data from both backups.