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From: Alexander Abraham <a.abraham@proxmox.com>
To: pve-devel@lists.proxmox.com
Cc: Alexander Abraham <a.abraham@proxmox.com>
Subject: [pve-devel] [ZFS on swap correction 1/1] Section on ZFS and swap corrected.
Date: Tue, 17 Dec 2024 10:30:19 +0100	[thread overview]
Message-ID: <20241217093019.30509-2-a.abraham@proxmox.com> (raw)
In-Reply-To: <20241217093019.30509-1-a.abraham@proxmox.com>

---
 local-zfs.adoc | 36 +-----------------------------------
 1 file changed, 1 insertion(+), 35 deletions(-)

diff --git a/local-zfs.adoc b/local-zfs.adoc
index c64fb27..bcd02f7 100644
--- a/local-zfs.adoc
+++ b/local-zfs.adoc
@@ -627,41 +627,7 @@ You *must reboot* to activate these changes.
 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.
-|===========================================================
+It is strongly recommended to not use a ZFS volume for a swap partition because this could lead to deadlocks freezing thge affected system and other unpredictable behavior. The OpenZFS documentation, which can be viewed https://openzfs.github.io/openzfs-docs/Project%20and%20Community/FAQ.html#using-a-zvol-for-a-swap-device-on-linux[here], warns against using a ZFS volume for a swap partition.
 
 [[zfs_encryption]]
 Encrypted ZFS Datasets
-- 
2.39.5



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  reply	other threads:[~2024-12-17  9:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-17  9:30 [pve-devel] [ZFS on swap correction 0/1] *** Added a warning about using Alexander Abraham
2024-12-17  9:30 ` Alexander Abraham [this message]
2024-12-19 12:01   ` [pve-devel] [ZFS on swap correction 1/1] Section on ZFS and swap corrected Fiona Ebner

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