The main takeaway of this picture is that your ZFS pool and thus your file system is based on one or more VDEVs. There are a few things you should take away from it. The schema above illustrates the architecture of ZFS. To understand why using ZFS may cost you extra money, we will dig a little bit into ZFS itself. This is ideal for home users because you can expand as you need. This is also true for many hardware-based RAID solutions.
Other software RAID solutions like Linux MDADM lets you grow an existing RAID array with one disk at a time. This fact is often overlooked, but it's very important when you are planning your build. With ZFS, you either have to buy all storage you expect to need upfront, or you will be wasting a few hard drives on redundancy you don't need. The key issue is that expanding capacity with ZFS is more expensive compared to legacy RAID solutions. But there is a caveat with ZFS that people should be aware of.Īlthough ZFS is free software, implementing ZFS is not free. Many home NAS builders consider using ZFS for their file system. RAIDZ expansion (most requested ZFS feature ever?) is coming, courtesy of Sneak preview at OpenZFS DevSummit!- OpenZFS October 19, 2017 Please note that RAIDZ expansion is under development. The bad news is that adding drives to an existing vdev may accrue some overhead, but the good news is that this overhead can be recovered. I have written a blogpost about this new feature. It will probably be available somewhere around August 2022. It seems that RAIDZ expansion is now being worked on.