Alex Owen wrote:
I have been using commands of the form: time dd if=/dev/zero of=/dev/volgroup/test bs=1M count=100 to get speeds for copying to a LVM device both WITH and WITHOUT a single snapshot. It seems that writes take >=10 times longer the first time a newly snapshot origin device is written to.
You may want to try the kernel patch posted here: http://marc.info/?l=dm-devel&m=118056593528910&w=1 That change gave me a significant speedup in similar tests. Kevin