Ultimately the protection level you end up running will depend on the amount of data you actually have, as that will determine the size and makeup of the cluster (I wasn't clear if you're asking about the 18 node cluster or some new cluster).  Your SE can take you through those permutations and show you which configurations (from a reliability standpoint) will be valid simply from a capacity standpoint.  Be sure to also consider any performance requirements you might have, i.e. you may want to opt for dense X-series nodes over dense archive (NL or HD) nodes, even though the latter could physically hold your data just fine.  As for the protection  of your small files... at 55 KiB, these files will be mirrored.  At the OneFS default protection of +2d:1n, that means 3x mirrored and so every 55 KiB file will consume 169.5 KiB in the filesystem.  At a protection of +3d:1n1d (a likely setting for a larger cluster), that 55 KiB file will consume 226 KiB and will be 4x mirrored.  You can use these efficiencies to estimate your total needed capacity.  You might also want to discuss future OneFS features like "containerization" with your account team.  For some very specific workflows, the ability to combine small files into large buckets can help tremendously with protection overhead.
Hello,  What would be the best protection level and node count for 55KB files (we store billions of 55k files..) in regards to overhead/efficiency, or does it even really matter with this size?  We are about to purchase a new cluster and would like to get some thoughts on the matter. We currently have an 18 node cluster with multiple pools but are getting killed with the overhead. I'm getting contradicting info from my reps...  Thanks, Oz
Best, most efficient, protection level for small files - 55KB