>To run those commands you must first `umount` to pool. Hence it being an offline job. No you don't need to unmount the pool under mdadm. You can do a live res

>To run those commands you must first `umount` to pool. Hence it being an offline job. No you don't need to unmount the pool under mdadm. You can do a live resize of the array. See the link I posted. >How many home users do you know who configure their own home raids using LVM and mdadm? Not many, hence me mentioning Syno and QNAP. >You said, and I quote, "2TB" (ie without any accumulation prefix). I said, quote, "if you add 2TB to a 4x1TB RAID5 array, you get 4TB of storage. If you add another 2TB you get 7TB of storage." >In fact what you've just described were is the exact solution that you called "unacceptable" in ZFS! Again, this is not what ZFS does, the mdadm solution stripes multiple RAID arrays over the same drive, which to my recollection is not a recommended configuration in ZFS by a long shot. >Lots of commercial tools do support that. I thought we were comparing ext4, LVM and mdadm to ZFS though? The commercial tools I mentioned previously use ext4, LVM and mdadm native functionality.