[pve-devel] [PATCH pve-docs v5] fix #5644: Moved the swap partition section

[Fiona Ebner]

Am 27.05.25 um 12:35 schrieb Alexander Abraham:
> The section about "Creating SWAP partitions" lives in its own
> file and the warning about creating SWAP partitions on ZFS was
> moved back to the original file with all documentation about
> working with ZVols.
> 
> Signed-off-by: Alexander Abraham <a.abraham at proxmox.com>
> ---
>  local-zfs.adoc       | 42 ++++++----------------------------------
>  pve-swap-on-zfs.adoc | 46 ++++++++++++++++++++++++++++++++++++++++++++

This file should not be here.

>  pve-swap.adoc        | 36 ++++++++++++++++++++++++++++++++++
>  sysadmin.adoc        |  2 ++
>  4 files changed, 90 insertions(+), 36 deletions(-)
>  create mode 100644 pve-swap-on-zfs.adoc
>  create mode 100644 pve-swap.adoc
> 
> diff --git a/local-zfs.adoc b/local-zfs.adoc
> index c64fb27..77d1055 100644
> --- a/local-zfs.adoc
> +++ b/local-zfs.adoc
> @@ -1,6 +1,7 @@
>  [[chapter_zfs]]
>  ZFS on Linux
>  ------------
> +
>  ifdef::wiki[]
>  :pve-toplevel:
>  endif::wiki[]

Already mentioned this in v4:

This hunk seems unrelated. If there is a reason for it, please send it
as a separate patch.

> @@ -622,46 +623,15 @@ 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.
> -|===========================================================
> +Do not use a ZFS volume for creating a swap

Style nit: The line break here is very early, more words fit until the
limit is reached.

> +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.
>  
>  [[zfs_encryption]]
>  Encrypted ZFS Datasets
> diff --git a/pve-swap-on-zfs.adoc b/pve-swap-on-zfs.adoc

> diff --git a/pve-swap.adoc b/pve-swap.adoc
> new file mode 100644
> index 0000000..6aac186
> --- /dev/null
> +++ b/pve-swap.adoc
> @@ -0,0 +1,36 @@
> +[[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[]

Includes the wrong file.

> +
>  include::local-lvm.adoc[]
>  
>  include::local-zfs.adoc[]