Re: Memory. 100TB OSD?

[Christian Wuerdig <christian.wuerdig@xxxxxxxxx>]

Generally the memory requirements are for ceph itself - the rest of
the system will also require some RAM, so you should probably add a
1GB basic footprint anyway. Plus the memory recommendations are more
general guidelines which often are more applicable to systems with
more OSDs for averaging the need between individual OSD processes. So
your basic footprint would probably be more like 4GB RAM for a small
OSD node. At least on my hacked together home toy cluster all nodes
run 4GB RAM and haven't been OOMed yet, although it's still running
Jewel so not sure if Luminous will have a massive impact.

Regarding the OSD size - more OSDs are generally better since access
to a single OSD is generally sequential AFAIK (OPs are queued per
OSD). Some people do run RAID backed OSDs but not of that size.
With Luminous it's not quite clear to me if it's RAM GB/OSD or still
GB/TB or something in between.

On Thu, Aug 31, 2017 at 5:30 AM, Two Spirit <twospirit6905@xxxxxxxxx> wrote:
> I've been seeing luminous OSD spit out error messages about out of
> memory even tho I was within the minimum memory requirements
> documented. 2GB with 2TB. I've also tested with 1.5TB, 1TB, and 500GB
> configurations.
>
> I've got 100TB single chassis file servers in production. Does this
> mean that to run an OSD on them I need 100GB RAM?
>
> And am I supose to run 1 daemon per 10T disk or since I've go the
> disks in a RAID, can I run 1 daemon for the whole of the 100TB
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