Appending to backup set requires another member

[hendrywan]

I am running Retrospect 5.0 on an AIT1 Drive, backing up to AIT Data Cartridges 35GB Native/91GB Compressed. Recycled backup of currently about 36GB of data on a Mac OS X Server. Daily backup. Hardware data compression.

 

PROBLEM: A second tape (to the backup set) is asked for on some days but not on other days - inconsistent! For example, one day it says: "Available: 32.5 G, assuming media capacity of 68.4 G" and the next day it says: "Available: Appending requires another member."

 

QUESTION: Why this inconsistency? How do I fix it? Surely it is not because the tape is full (if so, it would be asking for a second tape every day, wouldn't it?).

 

Thanks for any suggestions and solutions.

 

Hendry