Clarification on Ceph OSD Memory Recommendation

[ryantw]

Hi all,

I'm wondering about this recommendation for memory requirements for Ceph from the Proxmox VE admin guide: "1 TiB of data, 1 GiB of memory"

I've not seen this elsewhere. Ceph's offical docs have a recommendation of 4 GiB per OSD, though are clear that OSDs can benefit from more memory.

I'm trying to understand where the 1 GiB per 1 TiB recommendation fits:

• It sounds like this is in addition to the per-OSD memory requirement? 4 GiB + 1 GiB per TiB for every OSD?
• If I have ten 10 TiB drives, for a total of ten OSDs and 100 TiB storage, would I really need to dedicate 140 GiB of memory to OSDs?
• Does this recommendation mean that the osd_memory_target parameter should be adjusted, or is this memory anticipated to be used in some other way?
• Is this recommendation due to the co-location of Proxmox and VMs on the same hardware as Ceph in any way?

Thanks in advance.