> md RAID will require a lengthy reshape Array reshapes are rare, and it'll only use idle IO bandwidth anyway. Redundancy is guaranteed during the whole proces

> md RAID will require a lengthy reshape Array reshapes are rare, and it'll only use idle IO bandwidth anyway. Redundancy is guaranteed during the whole process. So I don't see this as a problem. > BTRFS supports adding a new drive, reshape (balance) is optional Thanks for pointing this out. I didn't know btrfs supported array reshapes. I'm waiting for it to mature (RAID5/6 was only added in 3.19, for example) but I expect I'll switch over at some point, probably at the point it's considered "boring" (exactly the experience I want from my filesystems).