R11.1 - Compression rate to a USB Drive

[Stat1c]

Window 2000 Server SP4.
Running R11.1
Device is a USB connected HP C7438A (Product DW027A) (Firmware ZU5A)
At the moment am getting 47gb onto the tape before it's asking for another tape, with a throughput of averaging 235 mb/min
The media is DAT72.
As USB connected drives are pretty new to me, does anyone use the same kind of set up and get nearer to the Golden 6mb/s compression transfer rate and closer to the 72gb Compressed capacity?
Am currently testing with the latest firmware on the HP drive of ZU75, but am wanting to know if i'm flogging a dead horse.

Thanks

Get Fat Up!

 

[DaveNeubauer]

I have a similar problem. Same USB tape drive running on Server 2003, using ARCserve r11.5. I should be able to get 36 GB per tape, but I am using five tapes to backup 134.6 GB of data. I checked and I'm using hardware compression. Very strange.