I have 5 hard drives, where I want to keep my data. Some of my files are more important, and some of them are less. So some of them I wish to put on RAID-6, and for some it RAID-5 is sufficient. It is difficult to predict at the moment of creation of the arrays how much space of each type to declare.

What I would do if I didn't hear about zfs, is partition the hard drives into identical 100GB partitions, and as my needs grow, assemble those partitions into md devices using linux-raid. Then, I'd combine those devices using lvm into logical volumes where I'd put my data. So when I'd need more space of e.g. RAID-6, I'd take 100GB partition from each hard drive and assemble them into another RAID-6 md device and would use it as physical storage for the logical volume group dedicated for RAID-6 data. Then I could grow the file system on this logical volume.

On top of RAID-6 and RAID-5 Volume Groups (managed by lvm) would reside completely independent file systems, which I'd later merge with multiple mount --bind into a single directory structure that would reflect the logical structure of data rather that of the storage.

But now, when I heard about the ZFS with all the performance, data-healing and compression capabilities I cannot stop thinking if it can help me. If so, what do you think would be the best setup?