zvol default volblocksize - VERY BAD PERFORMANCE

Can you do some test with it ? Snap current volume and send it to you new volume with different block size and compare performance.
 
Can you do some test with it ? Snap current volume and send it to you new volume with different block size and compare performance.
I can't to do it now, but in the future - may be. I think there is no need to test it. Because a maintainer of zfs tell about wrong of 8k zvol for ARC!!! Can I tune it?