This may not be the answer you are looking for but one option is Ceph. Several cheap, low-power NAS boxes running Linux/Ceph and throw disk at them. Depending

This may not be the answer you are looking for but one option is Ceph. Several cheap, low-power NAS boxes running Linux/Ceph and throw disk at them. Depending on the data you store you can have 3-way replication of Erasure Coding at your preferred risk/performance level. Disk failures are painless, box failures don't lose data, expansion and re-balancing scales with the number of disks and pretty quickly the limiting factor is your network (4-5 modern spinning disks can easily saturate a 10G network link).