[matheusmoreira]

How to expand the storage though? I want to be able to buy random drives and add them to the server. RAID and ZFS require identical drives: if I buy a 2 TB drive and a 4 TB drive, the 2 TB difference would be unused. In order to expand the capacity properly, I'd have to replace all the disks one by one with new 4 TB disks as if the old ones had failed. This process requires rebuilding the array and the chance of getting an uncorrectable read error is considerable.

[LoSboccacc]

you add all the disk and replicate on all four the 2T partition, then remove the old disk then extend the partition. this is significantly easier if it all started with lvm on top of the raid but not impossible without.