zvol default volblocksize - VERY BAD PERFORMANCE

[VGusev2007]

Dear all, I think it is a very bad idea, to create zvol with 8k volblocksize.

Can I change a default block size of zvol when created a vm from web gui?

I want to change it from 8k to 128k.

If you want to see a more about problem, you can go to: https://github.com/zfsonlinux/zfs/issues/824

 

[Nemesiz]

Can you do some test with it ? Snap current volume and send it to you new volume with different block size and compare performance.

 

[VGusev2007]

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?

 

[mir]

If you want to see a more about problem, you can go to: https://github.com/zfsonlinux/zfs/issues/824

But last post says this issue has been resolved?

 

[VGusev2007]

But last post says this issue has been resolved?

yes, but you still have problem with an effectivity of ARC.

 

[melanch0lia]

yes, but you still have problem with an effectivity of ARC.

More details please

 

[VGusev2007]

More details please

You need a more RAM for ARC in this case. There is no other moment with it. 8k - is good size for zvol too.

And I don't use zfs on linux anymore, bacause it has some bugs (my VMs hangs in during heavy disk i/o). I use lvmcache now.