We have Decru hardware devices on the wire between our VTL and our robot, and it encrypts at wire speed, i.e. we see no performance impact whatsoever. The only limits are caused by the port speed on the hba or switches.
We had an incredible and annoying array of problems when we started - mostly caused by mixing hosts - Solaris and HP apparently do not coexist well, but once we put the VTL in between and only have the one OS involved we have smooth sailing.
We also use the decru to encrypt some of our disks, so our data at rest is encrypted.
We do have a saying - "do NOT taunt the Decru" - because of the issues in the past...
