[[storage_zfs]]
ZFS over ISCSI Backend
----------------------
ifdef::wiki[]
:pve-toplevel:
:title: Storage: ZFS over ISCSI
endif::wiki[]

Storage pool type: `zfs`

This backend accesses a remote machine having a ZFS pool as storage and an iSCSI
target implementation via `ssh`. For each guest disk it creates a ZVOL and,
exports it as iSCSI LUN. This LUN is used by {pve} for the guest disk.

The following iSCSI target implementations are supported:

* LIO (Linux)
* IET (Linux)
* ISTGT (FreeBSD)
* Comstar (Solaris)

NOTE: This plugin needs a ZFS capable remote storage appliance, you cannot use
it to create a ZFS Pool on a regular Storage Appliance/SAN


Configuration
~~~~~~~~~~~~~

In order to use the ZFS over iSCSI plugin you need to configure the remote
machine (target) to accept `ssh` connections from the {pve} node. {pve} connects to the target for creating the ZVOLs and exporting them via iSCSI.
Authentication is done through a ssh-key (without password protection) stored in
`/etc/pve/priv/zfs/<target_ip>_id_rsa`

The following steps create a ssh-key and distribute it to the storage machine
with IP 192.0.2.1:

----
mkdir /etc/pve/priv/zfs
ssh-keygen -f /etc/pve/priv/zfs/192.0.2.1_id_rsa
ssh-copy-id -i /etc/pve/priv/zfs/192.0.2.1_id_rsa.pub root@192.0.2.1
ssh -i /etc/pve/priv/zfs/192.0.2.1_id_rsa root@192.0.2.1
----

The backend supports the common storage properties `content`, `nodes`,
`disable`, and the following ZFS over ISCSI specific properties:

pool::

The ZFS pool/filesystem on the iSCSI target. All allocations are done within that
pool.

portal::

iSCSI portal (IP or DNS name with optional port).

target::

iSCSI target.

iscsiprovider::

The iSCSI target implementation used on the remote machine

comstar_tg::

target group for comstar views.

comstar_hg::

host group for comstar views.

lio_tpg::

target portal group for Linux LIO targets

nowritecache::

disable write caching on the target

blocksize::

Set ZFS blocksize parameter.

sparse::

Use ZFS thin-provisioning. A sparse volume is a volume whose
reservation is not equal to the volume size.


.Configuration Examples (`/etc/pve/storage.cfg`)
----
zfs: lio
   blocksize 4k
   iscsiprovider LIO
   pool tank
   portal 192.0.2.111
   target iqn.2003-01.org.linux-iscsi.lio.x8664:sn.xxxxxxxxxxxx
   content images
   lio_tpg tpg1
   sparse 1

zfs: solaris
   blocksize 4k
   target iqn.2010-08.org.illumos:02:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx:tank1
   pool tank
   iscsiprovider comstar
   portal 192.0.2.112
   content images

zfs: freebsd
   blocksize 4k
   target iqn.2007-09.jp.ne.peach.istgt:tank1
   pool tank
   iscsiprovider istgt
   portal 192.0.2.113
   content images

zfs: iet
   blocksize 4k
   target iqn.2001-04.com.example:tank1
   pool tank
   iscsiprovider iet
   portal 192.0.2.114
   content images
----

Storage Features
~~~~~~~~~~~~~~~~

The ZFS over iSCSI plugin provides a shared storage, which is capable of
snapshots. You need to make sure that the ZFS appliance does not become a single
point of failure in your deployment.

.Storage features for backend `iscsi`
[width="100%",cols="m,m,3*d",options="header"]
|==============================================================================
|Content types  |Image formats  |Shared |Snapshots |Clones
|images         |raw            |yes    |yes        |no
|==============================================================================