> Normally we fear expanding a home server because resizing a RAID always means copying terabytes of data off somewhere else, wiping the lot and constructing a new one including the original disks.
This is just wrong. Only last week I resized my RAID5 array from 2 drives (basically RAID1) to 4 drives. Reshaping and resizing the ext4 partition was all done online with minimal performance impact. The only bit that took a long time was the reshaping, and even then it managed to add a new 2TB drive in only a few hours.
Even upgrading the entire array to use a larger size of disk is pretty easy. You do need all the disks to be the same size though :(
It's also wrong on the opposite front: ZFS cannot change geometries on the fly. I am a fairly big fan of ZFS, but the ability to mix disk sizes and change numbers of disks in a RAIDZ set is not why--it effectively cannot do either.
This is just wrong. Only last week I resized my RAID5 array from 2 drives (basically RAID1) to 4 drives. Reshaping and resizing the ext4 partition was all done online with minimal performance impact. The only bit that took a long time was the reshaping, and even then it managed to add a new 2TB drive in only a few hours.
Even upgrading the entire array to use a larger size of disk is pretty easy. You do need all the disks to be the same size though :(