Proxmox 4.0 with zfs raid 1

[pizza]

I'm testing Proxmox 4.0 with 2x 1TB sata disks and ZFS raid 1. In the past with Proxmox 3.x and mdadm softraid the overal performance was better. Zfs takes a amount of cpu time. Can the performance with zfs improved by simply adding a SSD disk as cache?

With zfs sync=standard (enabled)

FSYNCS-SECOND: 105.66

sync disabled
FSYNCS-SECOND: 16099.22

 

[Erk]

ZFS needs an SSD read (L2ARC) and write (ZIL) cache to perform well.

The CPU usage is most likely the default compression enabled. You need a stack of RAM too for the ARC cache. I tried ZFS on a test system that had only 6GB and the CPU usage went crazy installing the iso for the test VM which was a BlueOnyx distro. It took almost an hour to install, normally takes 10min. the server load was about 7.00 most of the time, CPU running flat out, no L2ARC or ZIL.

 

[pizza]

ZFS needs an SSD read (L2ARC) and write (ZIL) cache to perform well.

The CPU usage is most likely the default compression enabled. You need a stack of RAM too for the ARC cache. I tried ZFS on a test system that had only 6GB and the CPU usage went crazy installing the iso for the test VM which was a BlueOnyx distro.

My server has 8 GB ram, disabling sync speeds up the system with only 2x sata disk and iowait nearly zero. My idea was to replace mdadm (tricky to install with proxmox) with zfs raid1 because Proxmox zfs raid1 is easy to install with the gui.

 

[danb35]

disabling sync speeds up the system with only 2x sata disk and iowait nearly zero.

That suggests that an SLOG would help out.