As for using the "cache" parameter with libvirt: this was buggy in Karmic and works correctly only in Lucid.
See this for details: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/531741
The bug was fixed in libvirt 0.7.5-5ubuntu11 and Lucid's current version is 0.7.5-5ubuntu27.
As for using the "cache" parameter with libvirt: this was buggy in Karmic and works correctly only in Lucid. /bugs.launchpad .net/ubuntu/ +source/ libvirt/ +bug/531741
See this for details: https:/
The bug was fixed in libvirt 0.7.5-5ubuntu11 and Lucid's current version is 0.7.5-5ubuntu27.