Storage: ZFS

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tbd. (running zfs on Proxmox VE is not officially supported)

Native ZFS for Linux on Proxmox

2013-03-27: 0.6.1 ZFSOnLinux (ZoL) is now ready for wide scale deployment on everything from desktops to super computers. See announcement

check See the Documentation and Community Resources for more information and help.

using Debian Wheezy packages from zfsonlinux

Important , on each pve kernel upgrade, you'll need to manually install headers, make symlink and rebuild modules.

For PVE on Wheezy [ 3.0+ ].

2013-05-29 - Debian Packages DKMS style packages for Debian are available from the repository. These packages track the latest official upstream tag and are refreshed as new releases are made available from .

also check

  • make sure pve headers are installed. if not :
aptitude install pve-headers-$(uname -r)
  • I think the ln is still needed.
ln -s /lib/modules/$(uname -r)/build /lib/modules/$(uname -r)/source
then follow instructions from , i copied here , but check link in case these changed:
su -
dpkg -i zfsonlinux_1~wheezy_all.deb
apt-get update
apt-get install debian-zfs

you should see zfs and spl module builds... check if OK

# ls -l /lib/modules/$(uname -r)/updates/dkms/
total 3128
-rw-r--r-- 1 root root  340944 May 29 10:25 splat.ko
-rw-r--r-- 1 root root  302104 May 29 10:25 spl.ko
-rw-r--r-- 1 root root   13392 May 29 10:27 zavl.ko
-rw-r--r-- 1 root root   71232 May 29 10:27 zcommon.ko
-rw-r--r-- 1 root root 1935120 May 29 10:27 zfs.ko
-rw-r--r-- 1 root root  130408 May 29 10:27 znvpair.ko
-rw-r--r-- 1 root root   40424 May 29 10:27 zpios.ko
-rw-r--r-- 1 root root  330368 May 29 10:27 zunicode.ko


test the above again and update the instructions as necessary.
does dkms auto build modules when pve kernel is upgraded? for that to happen headers would need to be installed and the ln may be needed.

pve kernel upgrade

currently this needs to be done when a kernel upgrade is done.

  • before reboot
# 1- you need to replace the XX with numbers from new kernel version:
aptitude  install pve-headers-2.6.32-XX-pve

# 2- you need to replace the XX with numbers from new kernel version:
ln -s /lib/modules/2.6.32-XX-pve/build /lib/modules/2.6.32-XX-pve/source

# 3- this will force modules to be  built
#    the more pve kernels installed the longer this takes. [ remove old ones ].
aptitude  reinstall spl-dkms  zfs-dkms

# 4- make sure modules are installed ok:
ls -l /lib/modules/2.6.32-XX-pve/updates/dkms/

# 5- reboot to use new kernel

some might want to put that to motd or save as a text file at /root/

kvm tuning

see thread on prox forum , per user Nemesiz :

  • pool:
zfs set primarycache=all tank
  • kvm config:
  • change cache to Write Back
You can do it using web GUI or manually. Example:
ide0: data_zfs:100/vm-100-disk-1.raw,cache=writeback

if not set this happened:

qm start 4016
kvm: -drive file=/data/pve-storage/images/4016/vm-4016-disk-1.raw,if=none,id=drive-virtio1,aio=native,cache=none: could not open disk image /data/pve-storage/images/4016/vm-4016-disk-1.raw: Invalid argument

Install on a high performance system

As of 2013 high performance servers have 16-64 cores, 256GB-1TB RAM and potentially many 2.5" disks and/or a PCIe based SSD with half a million IOPS. High performance systems benefit from a number of custom settings, for example enabling compression typically improves performance.

  • If you have a good number of disks keep organized by using aliases. Edit /etc/zfs/vdev_id.conf to prepare aliases for disk devices found in /dev/disk/by-id/ :
# run 'udevadm trigger' after updating this file
alias a0        scsi-36848f690e856b10018cdf39854055206
alias b0        scsi-36848f690e856b10018cdf3ce573fdeb6
alias a1        scsi-36848f690e856b10018cdf40f5b277cbc
alias b1        scsi-36848f690e856b10018cdf43a5db1b99b
alias a2        scsi-36848f690e856b10018cdf4575f652ad0
alias b2        scsi-36848f690e856b10018cdf47761587cec

Use flash for caching/logs. If you have only one SSD, use cfdisk to create a small partion for the ZIL (ZFS intent log) and a larger one for the L2ARC (ZFS read cache on disk). Make sure that the ZIL is on the first partition. In our case we have a Express Flash PCIe SSD with 175GB capacity and setup a ZIL with 25GB and a L2ARC cache partition of 150GB

  • edit /etc/modprobe.d/zfs.conf​ to apply several tuning options for high performance servers:
# ZFS tuning for a proxmox machine that reserves 64GB for ZFS
# Don't let ZFS use less than 4GB and more than 64GB
options zfs zfs_arc_min=4294967296
options zfs zfs_arc_max=68719476736
# disabling prefetch is no longer required
options zfs l2arc_noprefetch=0
  • create a zpool of striped mirrors (equivalent to RAID10) with log device and cache and always enable compression:
zpool create -o compression=on -f tank mirror a0 b0 mirror a1 b1 mirror a2 b2 log /dev/rssda1 cache /dev/rssda2​
  • ​​​​​​​​check the status of the newly created pool:
root@proxmox:/# zpool status
  pool: tank
 state: ONLINE
  scan: none requested

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            a0      ONLINE       0     0     0
            b0      ONLINE       0     0     0
          mirror-1  ONLINE       0     0     0
            a1      ONLINE       0     0     0
            b1      ONLINE       0     0     0
          mirror-2  ONLINE       0     0     0
            a2      ONLINE       0     0     0
            b2      ONLINE       0     0     0
          rssda1    ONLINE       0     0     0
          rssda2    ONLINE       0     0     0

errors: No known data errors

Using PVE 2.3 on a 2013 high performance system with ZFS you can install Windows Server 2012 Datacenter Edition with GUI in just under 4 minutes.

zfs links and docs

and this has some very important information to know before implementing zfs on a production system.

check these well written manual pages:

man zfs

man zpool

zfs mounting workaround

The default zfs mount -a script runs too late in the boot process for most system scripts. The following make zfs mounts start on time.

2014-01-22 the info below came from this excellent wiki page:

  • Edit /etc/default/zfs and set ZFS_MOUNT='yes'
  • edit /etc/insserv.conf,
and at the end of the $local_fs line,
add zfs-mount (without a plus).
# All local filesystems are mounted (done during boot phase)
$local_fs       +mountall +mountall-bootclean +mountoverflowtmp +umountfs

edit /etc/init.d/zfs-mount and find three lines near the top, changing them like this:

# Required-Start:
# Required-Stop:
# Default-Start: S

note remove the Required-Start and -Stop entries.

  • Activating init.d changes Then run:
insserv -v -d zfs-mount

I had an issue with pve storage on zfs, before pve would start before zfs and create directories at the zfs mount point. to fix that start single user mode and remove the directories [ make sure they are empty.... ].

also see