With 4gb, it won't do well, from experience. FreeNAS, which is generally the set and forget ZFS option, wants 1gb per Tb of data, but can cope with 1gb per 3tb

With 4gb, it won't do well, from experience. FreeNAS, which is generally the set and forget ZFS option, wants 1gb per Tb of data, but can cope with 1gb per 3tb. It's more of a cache issue with the Cluster and drive size. IIIRC, 6gb or 8gb on FreeNAS enables the read ahead caching and a few other tweaks. But it's still not fast. Once the initial file write/read cache is empty, you get the regular throughout, which is 5-12mb /sec on a slow system, basically however fast the CPU and HDD can search for and supply the data in surges. setting up a HP N54L microserver with 5x 4tb drives and the standard 4gb, (getting the compatible non registered ECC DDR is ridiculous), Gigabit transfers just slow down to USB v1 speed. Booting up with 16gb ECC, I get 85mb/sec Gigabit transfers with no problems. For a box that's job is storing movies and TV, music and photos for plex, it doesn't have to do a lot. Transcoding would be nice, but not worth the extra. All up, 20tb was $1500,$400 on top of the wddriveWD red NAS drives.