got a question, very new to raid != 1/0 systems here. I have 2x3TB hard disks + 2x2tb hard disks + 1x1tb hard disk which I would like to "group" in a RAID-X having some sort of fault tollerance. Do you think it's possible without losing space? Which kind of RAID? Actually they're setup (3+3 and 2+2, 1 is mounted alone) in 2 different mdadm arrays mirroring, but the second is pretty much empty and I would like to "group" to expand the first one.

  • Hi alestark! Welcome to AskUbuntu! Have you looked into BTRFS? It will guarantee you fault tolerance and redundancy while making the most of the space available in any combination of disks. Just add all the disks to the one BTRFS volume and then tell it to balance and it will make sure it meets the redundancy and fault tolerance you specify without the need for RAID. Aug 19, 2021 at 4:52
  • thanks for the answer! I'll have a look. Does it provides as well the possibility to swap a faulty drive and replace? In that case will the system reconstruct data by itself? What's the maximum tollerance IYO?
    – alestark
    Aug 19, 2021 at 4:59
  • Absolutely, and you can specify the maximum tolerance even after you've built the array just by "rebalancing" with a new configuration, with different values for metadata vs file data. It is a Copy-on-Write filesystem, though, so it might take a little to get your head around, but when configured right it can be faster than RAID. The main tradeoff being that it can't really tell you how much space is left with any real accuracy. Just don't use "RAID" mode because it's still not really stable. You want to specify the actual redundancy and let BTRFS handle the rest. Aug 19, 2021 at 5:09
  • I will give it a try, I'm using openmediavault and I can see it's not part of the official components list, but via cli it's possible to interact with it. Will search some info about, thanks for the suggestion!
    – alestark
    Aug 19, 2021 at 5:10


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