I missed a step in the calculation. The total_memory_kb I mentioned
earlier is also multiplied by the value of the
mgr/cephadm/autotune_memory_target_ratio before doing the subtractions for
all the daemons. That value defaults to 0.7. That might explain it seeming
like it's getting a value lower than expected. Beyond that, I'd think
'i'd
need a list of the daemon types and count on that host to try and work
through what it's doing.
On Wed, Mar 27, 2024 at 10:47 AM Mads Aasted <mads2a(a)gmail.com> wrote:
Hi Adam.
So doing the calculations with what you are stating here I arrive at a
total sum for all the listed processes at 13.3 (roughly) gb, for everything
except the osds, leaving well in excess of +4gb for each OSD.
Besides the mon daemon which i can tell on my host has a limit of 2gb ,
none of the other daemons seem to have a limit set according to ceph orch
ps. Then again, they are nowhere near the values stated in min_size_by_type
that you list.
Obviously yes, I could disable the auto tuning, but that would leave me
none the wiser as to why this exact host is trying to do this.
On Tue, Mar 26, 2024 at 10:20 PM Adam King <adking(a)redhat.com> wrote:
> For context, the value the autotune goes with takes the value from
> `cephadm gather-facts` on the host (the "memory_total_kb" field) and then
> subtracts from that per daemon on the host according to
>
> min_size_by_type = {
> 'mds': 4096 * 1048576,
> 'mgr': 4096 * 1048576,
> 'mon': 1024 * 1048576,
> 'crash': 128 * 1048576,
> 'keepalived': 128 * 1048576,
> 'haproxy': 128 * 1048576,
> 'nvmeof': 4096 * 1048576,
> }
> default_size = 1024 * 1048576
>
> what's left is then divided by the number of OSDs on the host to arrive
> at the value. I'll also add, since it seems to be an issue on this
> particular host, if you add the "_no_autotune_memory" label to the host,
> it will stop trying to do this on that host.
>
> On Mon, Mar 25, 2024 at 6:32 PM <mads2a(a)gmail.com> wrote:
>
>> I have a virtual ceph cluster running 17.2.6 with 4 ubuntu 22.04 hosts
>> in it, each with 4 OSD's attached. The first 2 servers hosting mgr's
have
>> 32GB of RAM each, and the remaining have 24gb
>> For some reason i am unable to identify, the first host in the cluster
>> appears to constantly be trying to set the osd_memory_target variable to
>> roughly half of what the calculated minimum is for the cluster, i see the
>> following spamming the logs constantly
>> Unable to set osd_memory_target on my-ceph01 to 480485376: error parsing
>> value: Value '480485376' is below minimum 939524096
>> Default is set to 4294967296.
>> I did double check and osd_memory_base (805306368) +
>> osd_memory_cache_min (134217728) adds up to minimum exactly
>> osd_memory_target_autotune is currently enabled. But i cannot for the
>> life of me figure out how it is arriving at 480485376 as a value for that
>> particular host that even has the most RAM. Neither the cluster or the host
>> is even approaching max utilization on memory, so it's not like there are
>> processes competing for resources.
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