[pbs-devel] [PATCH proxmox-backup] docs: add zfs_arc_min < zfs_arc_max note

[Fabian Grünbichler]

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---

Notes:
    this can happen via the PVE integration, which always sets the base64 flag
    except for the special value '/'.

 docs/local-zfs.rst | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/docs/local-zfs.rst b/docs/local-zfs.rst
index f36aefe8..bc20c841 100644
--- a/docs/local-zfs.rst
+++ b/docs/local-zfs.rst
@@ -246,6 +246,19 @@ host. Use your preferred editor to change the configuration in
 
 This example setting limits the usage to 8GB.
 
+.. IMPORTANT:: In case your desired `zfs_arc_max` value is lower than or equal to
+   `zfs_arc_min` (which defaults to 1/32 of the system memory), `zfs_arc_max`
+   will be ignored unless you also set `zfs_arc_min` to at most `zfs_arc_max -
+   1`.
+
+.. code-block:: console
+
+  options zfs zfs_arc_max=8589934592 zfs_arc_min=8589934591
+
+For example, to set the target ARC size to 8GB on a system with 256GB of total
+memory (or more), `zfs_arc_min` needs to be set to `8GB - 1` (`zfs_arc_max -
+1`) in order for `zfs_arc_max` to be honored.
+
 .. IMPORTANT:: If your root file system is ZFS you must update your initramfs every time this value changes:
 
 .. code-block:: console
-- 
2.20.1