We are actually able to utilize it with barely 3 nodes (all are M/C/D), using ZFS as the underlying FS and deviating a bit from the standard advice to 100 GB xmx, 300 GB for ZFS ARC cache and the rest kept for overhead.
It’s based on a few Raidz2 vdevs (each four disk wide) under one pool in each node.
We had an earlier cluster with 10 data nodes + 3 Master nodes with 64 GB/12 cores each which did just as well with some different configuration.
We’ve found ODFE to be quite versatile in the process
Adding on top of that, we’ve been able to achieve a performance of 1B+ documents indexed in 2 hours with this setup with no failures or queue on real workload. Which is what led us to deviation from the standard recommendations by Elastic