Francois Gouget wrote:
Indeed during the revert vm1 shows no read traffic (lots of RAM to cache that), but a steady 6 MB/s stream of writes ! In contrast on vm2 writes quickly ramp up to 80 MB/s, then stop after ~5 seconds and QEMU just uses CPU for the last ~4 seconds.
Maybe vm2 mounts its file systems with noatime? (see e.g. http://www.tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/cha... ). For vm3 that wouldn't make such a big difference because of its SSD.
Jonas