Compressing tapes

[jmobberley]

We are currently using Imitation DLT IV 35/70 tapes. The amount of data to backed up on our servers has surpassed 35GB, so the obvious thing to do is compress the tapes? Well I can't find help anywhere how to do this. In the 'compression type' option box, I changed it from Software to Harware(otherwise Software). This made no difference, and the tape drive is asking for another tape. Am I missing something? I thought about trying to format the tape to see if I could do it there, but the 'Format' option is greyed out in the menu.

Any ideas welcome!

Thanks

 

[jmobberley]

After further investigation of the log files, I have found that in fact 39GB has been "processed", and after calculating the amount using the compression ratios, the actual data amounts to 22.5GB ! Now I'm confused - I could understand it if the amount to be backed up was 60GB and it had been compressed to 40MB, so wouldn't fit on the tape.