Finally, the only way to get good performance (similar to LVM) was to upgrade ZFS 0.7.1 following these instructions:
I know this is an unsupported method, so I hope zfs 0.7.1 will be fully supported soon.
I haved created a new zvol with volblocksize=4k, asigned to the VM, cloned CentOS with dd to the new disk, and rebooted the VM with the new disk.
The performance increased dramatically! Now I get expected IOPS.
Maybe it would be a good idea to be able to change volblocksize when creating a new...
Hi! I understand your point, however I maded a new test:
I created a new VM, I installed then Centos 7 without LVM and ext4. If I do the fio test inside the VM the results are same ~5000 IOPS. However if I stop the VM and mount the zvol directly in the host (mount /dev/mapper/vm-102-disk-1p2...
Running fio test on a zvol directly on the host gets higher values! About 2x/3x faster! Not as fast as LVM but I think it will be enough.
Why the VM cannot get these IOPS?
I noticed while running FIO test directly on the host, iowait raises up to 50% but when running FIO on the VM, iowait on...
Both setups are similar, only difference is one server is ZFS backed and the other one is LVM.
1] According to Rhinox, zfs raid1 would have same write performance as single drive.
2] I know it, this is what I am testing, I expected to have some write penalty in ZFS, but my benchmarks shows 4x...