[PVE-User] Proxmox + ZFS: Performance issues

[Robert Fantini]

if those are not ssd drives, then  adding a zil drive will most likely help.

On Sat, Apr 23, 2016 at 2:15 PM, Ralf <ralf+pve at ramses-pyramidenbau.de>
wrote:

> Hi,
>
> I encounter very bad read/write performance on my mirror-zfs, even on
> hypervisor-side.
>
> After shutting down all VMs, reading and writing from raw ZFS block
> devices VMs runs at maximum 5MiB/s (tested with dd
> if=/dev/rpool/VM/disk-100 of=/dev/null) while reading from the
> underlying raw-disk (/dev/sda) has good performance (~100MiB/s). Of
> course, performance inside VMs is even worse. Any ideas?
>
> This is my setup:
> Proxmox / 4.1-30/9e199213 / Linux 4.4.6-1-pve / ZFS mirror, two disks
>
> ZFS setup:
>
> $ dmesg | grep ZFS
> [    2.882118] ZFS: Loaded module v0.6.5.6-1, ZFS pool version 5000, ZFS
> filesystem version 5
>
> $ zpool status
>         [snip]
>         NAME        STATE     READ WRITE CKSUM
>         rpool       ONLINE       0     0     0
>           mirror-0  ONLINE       0     0     0
>             sdb2    ONLINE       0     0     0
>             sda2    ONLINE       0     0     0
>
> ZFS module parameters:
> $ cat /etc/modprobe/zfs.conf
> options zfs zfs_arc_max=3221225472
>
> Partition alignement:
> $ parted /dev/sda
> (parted) align-check o 2
> 2 aligned
>
> Dedup: off
> Checksumming: on
> Compression: off
>
> Anything helps!
>
> Cheers
>   Ralf
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