Hi, We're considering the merits of enabling CephFS for our main Ceph cluster (which provides object storage for OpenStack), and one of the obvious questions is what sort of hardware we would need for the MDSs (and how many!). These would be for our users scientific workloads, so they would need to provide reasonably high performance. For reference, we have 3060 6TB OSDs across 51 OSD hosts, and 6 dedicated RGW nodes. The minimum specs are very modest (2-3GB RAM, a tiny amount of disk, similar networking to the OSD nodes), but I'm not sure how much going beyond that is likely to be useful in production. I've also seen it suggested that an SSD-only pool is sensible for the CephFS metadata pool; how big is that likely to get? I'd be grateful for any pointers :) Regards, Matthew -- The Wellcome Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.