Hi Steven,
It really depends on how large the active dataset size is that's being
accessed across all of the clients. The biggest consumer of memory in
the OSD typically is the onode cache. Reading onodes from disk is
expensive, so keeping the onode cache hit rate high (especially on NVMe)
is a pretty big performance win.
The suggestions you mentioned are probably fairly reasonable as an
initial rule-of-thumb, but you may want to scale up/down depending on
various factors. IE 8GB memory targets might be fine for NVMe backed
OSDs if the drives are smaller and if most of the data being stored is
cold. On the other hand, you might want more than 6GB per OSD if you
have big HDDs with many active users all storing tiny objects.
Mark
On 7/31/25 7:17 AM, Steven Vacaroaia wrote:
Hi
What is the best practice / your expert advice about using
osd_memory_target_autotune
on hosts with lots of RAM ?
My hosts have 1 TB RAM , only 3 NVMEs , 12 HDD and 12 SSD
Should I disable autotune and allocate more RAM?
I saw some suggestion for 16GB to NVME , 8GB to SSD and 6 to HDD
Many thanks
Steven
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