Storage Per Tape Differs Drastically

[tk421x]

I am having an issue with Retrospect Win 7.6.111. I backup to a VXA 320 External SCSI Drive & x23 160/320GB tapes. There are currently 5 members/tapes in use. The Backup Set Properties states that each tapes storage has been reduced by half as shown below.

 

1-Backup Set A = 174.8 GB Used

2-Backup Set A = 131.9 GB Used (131.9 ÷ 2 = 65.95)

3-Backup Set A = 62.2 GB Used (62.2 ÷ 2 = 31.1)

4-Backup Set A = 35.8 GB Used (35.8 ÷ 2 = 17.9)

5-Backup Set A = 16.4 GB Used

 

As you can see, I should only be on my 3rd tape but instead I'm going on my sixth.

 

So here are my questions:

 

1.) What could be causing this degradation? Is there a setting in Retrospect that I need to change?

2.) Is there a way for me to redistribute the data back to the earlier members regaining my missing space?

 

I can't afford to lose any of the existing data and I can't afford to keep buying tapes when they are expensive and only store 1/10th of what the estimated uncompressed volume should be.

 

Thank you in advance for your help in this matter.

 

[Mayoff]

http://kb.dantz.com/article.asp?article=5658&p=2