[pve-devel] [PATCH docs] storage: add minimal zfs over iscsi doc

[Stoiko Ivanov <s.ivanov@proxmox.com>]

mostly copied from the wiki-page[0], and adapted to include LIO as
target provider.

Additionally I added a note to explain that the plugin needs ZFS on
the target side (and does not make your SAN speak ZFS)

Tested during the PVE 7.0 tests for the plugin I did.

[0] https://pve.proxmox.com/wiki/Storage:_ZFS_over_iSCSI

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
I plan on adding this about once per Debian release (while testing and
wondering why we don't have that in our reference docs) - but the plan
usually gets replaced by something more urgent (and fun).

 pve-storage-zfs.adoc | 139 +++++++++++++++++++++++++++++++++++++++++++
 pvesm.adoc           |   2 +
 2 files changed, 141 insertions(+)
 create mode 100644 pve-storage-zfs.adoc

diff --git a/pve-storage-zfs.adoc b/pve-storage-zfs.adoc
new file mode 100644
index 0000000..6801873
--- /dev/null
+++ b/pve-storage-zfs.adoc
@@ -0,0 +1,139 @@
+[[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
+|==============================================================================
diff --git a/pvesm.adoc b/pvesm.adoc
index c8e2347..98c8c44 100644
--- a/pvesm.adoc
+++ b/pvesm.adoc
@@ -436,6 +436,8 @@ include::pve-storage-cephfs.adoc[]
 
 include::pve-storage-btrfs.adoc[]
 
+include::pve-storage-zfs.adoc[]
+
 
 ifdef::manvolnum[]
 include::pve-copyright.adoc[]
-- 
2.30.2