[linux-lvm] Should I expect snapshot origin LV's to be 10x slower?

[Kevin Jamieson]

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