From: Fiona Ebner <f.ebner@proxmox.com>
To: Proxmox VE development discussion <pve-devel@lists.proxmox.com>,
Alexander Abraham <a.abraham@proxmox.com>
Subject: Re: [pve-devel] [PATCH pve-docs v5] fix #5644: Moved the swap partition section
Date: Tue, 27 May 2025 13:35:22 +0200 [thread overview]
Message-ID: <82d7b678-ab0c-451a-a17d-7acffa37e114@proxmox.com> (raw)
In-Reply-To: <20250527103550.42279-1-a.abraham@proxmox.com>
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@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[]
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prev parent reply other threads:[~2025-05-27 11:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-27 10:35 Alexander Abraham
2025-05-27 11:35 ` Fiona Ebner [this message]
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