software compression vs hardware compression

Hi all,

I just wanted to share my experience.

I'm usually using hardware compression on my backup server (because all data to be backuped ,1.2TB, are local) to save it some CPU. As a result my backup were going quite fast (about 4 hours) but the load balancing was far from my expectation (backups were ranging from 250MB to 600MB or more; I regularly hit end-of-tape on my LTO3).

Recently, I had too much of this bad load-balancing, and I turned on software compression, just to give it a chance. As a result my backup was approx. 3 times slower so I decided to turn it off again.

But, what is great, is that, since I turned software compression on once, amanda seems to have a fairly good idea about how the data will be compressed by the hardware and the load-balancing is now far better (ranging from 400MB to 500MB).

So the conclusion are:

(1) Amanda does a really better job at load-balancing when using software compression (that's not just a "commercial" argument from Amanda's developers ;-p)
(2) Software compression eats a lot of CPU

Voilà,

Thanks amanda folks,

Cyrille