[pve-devel] [PATCH pve-docs] fix #5644: Moved the section on ZFS

[Alexander Abraham <a.abraham@proxmox.com>]

I moved the section on creating swap partitions on ZFS between
the "Disk Health Monitoring" section and the "Logical Volume
Manager" section. I also incorporated all suggestions Fiona
made, except one: No comma was put before "because" because
the subordinate clause is introduced by "because". One only
puts commas after suboridnate clauses if these introduce a
sentence.

Signed-off-by: Alexander Abraham <a.abraham@proxmox.com>
---
 local-zfs.adoc       | 42 +---------------------------------------
 pve-swap-on-zfs.adoc | 46 ++++++++++++++++++++++++++++++++++++++++++++
 sysadmin.adoc        |  2 ++
 3 files changed, 49 insertions(+), 41 deletions(-)
 create mode 100644 pve-swap-on-zfs.adoc

diff --git a/local-zfs.adoc b/local-zfs.adoc
index c64fb27..3c9564f 100644
--- a/local-zfs.adoc
+++ b/local-zfs.adoc
@@ -1,6 +1,7 @@
 [[chapter_zfs]]
 ZFS on Linux
 ------------
+
 ifdef::wiki[]
 :pve-toplevel:
 endif::wiki[]
@@ -622,47 +623,6 @@ time this value changes:
 You *must reboot* to activate these changes.
 ====
 
-
-[[zfs_swap]]
-SWAP on ZFS
-~~~~~~~~~~~
-
-Swap-space created on a zvol may generate some troubles, like blocking the
-server or generating a high IO load, often seen when starting a Backup
-to an external Storage.
-
-We strongly recommend to use enough memory, so that you normally do not
-run into low memory situations. Should you need or want to add swap, it is
-preferred to create a partition on a physical disk and use it as a swap device.
-You can leave some space free for this purpose in the advanced options of the
-installer. Additionally, you can lower the
-``swappiness'' value. A good value for servers is 10:
-
-----
-# sysctl -w vm.swappiness=10
-----
-
-To make the swappiness persistent, open `/etc/sysctl.conf` with
-an editor of your choice and add the following line:
-
---------
-vm.swappiness = 10
---------
-
-.Linux kernel `swappiness` parameter values
-[width="100%",cols="<m,2d",options="header"]
-|===========================================================
-| Value               | Strategy
-| vm.swappiness = 0   | The kernel will swap only to avoid
-an 'out of memory' condition
-| vm.swappiness = 1   | Minimum amount of swapping without
-disabling it entirely.
-| vm.swappiness = 10  | This value is sometimes recommended to
-improve performance when sufficient memory exists in a system.
-| vm.swappiness = 60  | The default value.
-| vm.swappiness = 100 | The kernel will swap aggressively.
-|===========================================================
-
 [[zfs_encryption]]
 Encrypted ZFS Datasets
 ~~~~~~~~~~~~~~~~~~~~~~
diff --git a/pve-swap-on-zfs.adoc b/pve-swap-on-zfs.adoc
new file mode 100644
index 0000000..aec3a70
--- /dev/null
+++ b/pve-swap-on-zfs.adoc
@@ -0,0 +1,46 @@
+[[zfs_swap]]
+SWAP on ZFS
+-----------
+
+It is strongly recommended to not use a ZFS volume for creating a swap 
+partition because this could lead to deadlocks. These deadlocks could 
+cause the affected system to freeze. The OpenZFS documentation 
+footnote:[https://openzfs.github.io/openzfs-docs/Project%20and%20Community/FAQ.html#using-a-zvol-for-a-swap-device-on-linux]
+warns about using a ZFS volume for creating a swap partition.
+
+[[creating_swap_partitions]]
+Creating SWAP Partitions
+------------------------
+
+We strongly recommend to use enough memory, so that you normally do not
+run into low memory situations. Should you need or want to add swap, it is
+preferred to create a partition on a physical disk and use it as a swap device.
+You can leave some space free for this purpose in the advanced options of the
+installer. Additionally, you can lower the
+``swappiness'' value. A good value for servers is 10: 
+
+----
+# sysctl -w vm.swappiness=10
+----
+
+To make the swappiness persistent, open `/etc/sysctl.conf` with
+an editor of your choice and add the following line:
+
+--------
+vm.swappiness = 10
+--------
+
+.Linux kernel `swappiness` parameter values
+[width="100%",cols="<m,2d",options="header"]
+|===========================================================
+| Value               | Strategy
+| vm.swappiness = 0   | The kernel will swap only to avoid
+an 'out of memory' condition
+| vm.swappiness = 1   | Minimum amount of swapping without
+disabling it entirely.
+| vm.swappiness = 10  | This value is sometimes recommended to
+improve performance when sufficient memory exists in a system.
+| vm.swappiness = 60  | The default value.
+| vm.swappiness = 100 | The kernel will swap aggressively.
+|===========================================================
+
diff --git a/sysadmin.adoc b/sysadmin.adoc
index dd43f73..9b2db52 100644
--- a/sysadmin.adoc
+++ b/sysadmin.adoc
@@ -71,6 +71,8 @@ include::pve-external-metric-server.adoc[]
 
 include::pve-disk-health-monitoring.adoc[]
 
+include::pve-swap-on-zfs.adoc[]
+
 include::local-lvm.adoc[]
 
 include::local-zfs.adoc[]
-- 
2.39.5



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