The section "SWAP on ZFS" was split into two parts. The first part contains general instructions on how to create a swap partition and how to set the level of "swappiness". The second part contains a warning about creating a swap partition on a ZFS volume.The official ZFS documentation, which has been linked in a footnote, explains that creating a swap partition on a ZFS volume could lead to dangerous and undefined behavior.
Signed-off-by: Alexander Abraham <a.abra...@proxmox.com> --- local-zfs.adoc | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/local-zfs.adoc b/local-zfs.adoc index c64fb27..d411222 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -622,14 +622,9 @@ 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. +[[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 @@ -637,18 +632,18 @@ 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"] |=========================================================== @@ -663,6 +658,15 @@ improve performance when sufficient memory exists in a system. | vm.swappiness = 100 | The kernel will swap aggressively. |=========================================================== +[[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. + [[zfs_encryption]] Encrypted ZFS Datasets ~~~~~~~~~~~~~~~~~~~~~~ -- 2.39.5 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
