thanks for the patch! see inline for comments
On 2025-09-18 18:45, Alwin Antreich wrote:
Since bluestore, OSDs adhere to the osd_memory_target and the
recommended amount of memory was increased.
See: https://docs.ceph.com/en/reef/start/hardware-recommendations/#ram
Signed-off-by: Alwin Antreich <[email protected]>
---
pveceph.adoc | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/pveceph.adoc b/pveceph.adoc
index 17efa4d..a2d71e7 100644
--- a/pveceph.adoc
+++ b/pveceph.adoc
@@ -131,14 +131,14 @@ carefully planned out and monitored. In addition to the
predicted memory usage
of virtual machines and containers, you must also account for having enough
memory available for Ceph to provide excellent and stable performance.
-As a rule of thumb, for roughly **1 TiB of data, 1 GiB of memory** will be used
-by an OSD. While the usage might be less under normal conditions, it will use
-most during critical operations like recovery, re-balancing or backfilling.
-That means that you should avoid maxing out your available memory already on
-normal operation, but rather leave some headroom to cope with outages.
-
-The OSD service itself will use additional memory. The Ceph BlueStore backend
of
-the daemon requires by default **3-5 GiB of memory** (adjustable).
+While usage may be less under normal conditions, it will consume more memory
+during critical operations, such as recovery, rebalancing, or backfilling. That
+means you should avoid maxing out your available memory already on regular
+operation, but rather leave some headroom to cope with outages.
+
+The current recommendation is to configure at least **8 GiB of memory per OSD
+daemon** for good performance. The OSD daemon requires, by default, 4 GiB of
+memory.
given how the current latest Ceph docs phrase it [0], I am not sure
here. They sound like the default osd_memory_target of 4G is okay, but
that they might use more in recovery situations and one should calculate
with ~8G.
So unless I understand that wrong, maybe we could phrase it more like
the following?
===
The current recommendation is to calculate with at least 8 GiB of memory
per OSD daemon to give it enough memory if needed. By default, the OSD
daemon is set to use up to 4 GiB of memory in normal scenarios.
===
If I understand it wrong and users should change the osd_memory_target
to 8 GiB, we should document how, or maybe even try to make it
configurable in the GUI/API/pveceph...
[0] https://docs.ceph.com/en/latest/start/hardware-recommendations/#ram
[[pve_ceph_recommendation_network]]
.Network
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