Backup with compression wierd size

Derekg

I have many DB's being backed up with level 4 compression. All the backup files appear to have normal sizes (ie 80-90% compressed) however one database takes a very long time to backup and only appears to be 20-30% compressed over regular SQL 2005 backups.

What would cause this behavior?

petey

Highly possible that the data in that database is not very compressible, e.g. perhaps it's already been compressed or it's encrypted.

A simple test to check if this is the case is to take a regular backup, and try compressing the backup file using a regular compression app e.g. Winzip or 7-zip, and compare the compression ratio with that of SQL Backup.

Thanks.