this post was submitted on 23 Feb 2026
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Seeking guidance on BTRFS RAID (lemmy.ml)
submitted 1 day ago by GnuLinuxDude@lemmy.ml to c/linux@lemmy.ml
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I'm installing 3x2TB HDDs into my desktop pc. The drives are like-new.

Basically they will replace an ancient 2tb drive that is failing. The primary purpose will basically be data storage, media, torrents, and some games installed. Losing the drives to failure would not be catastrophic, just annoying.

So now I'm faced with how to set up these drives. I think I'd like to do a RAID to present the drives as one big volume. Here are my thoughts, and hopefully someone can help me make the right choice:

  • RAID0: Would have been fine with the risk with 2 drives, but 3 drives seems like it's tempting fate. But it might be fine, anyhow.
  • RAID1: Lose half the capacity, but pretty braindead setup. Left wondering why pick this over RAID10?
  • RAID10: Lose half the capacity... left wondering why pick this over RAID1?
  • RAID5: Write hole problem in event of sudden shutoff, but I'm not running a data center that needs high reliability. I should probably buy a UPS to mitigate power outages, anyway. Would the parity calculation and all that stuff make this option slow?

I've also rejected considering things like ZFS or mdadm, because I don't want to complicate my setup. Straight btrfs is straightforward.

I found this page where the person basically analyzed the performance of different RAID levels, but not with BTRFS. https://larryjordan.com/articles/real-world-speed-tests-for-different-hdd-raid-levels/ (PDF link with harder numbers in the post). So I'm not even sure if his analysis is at all helpful to me.

If anyone has thoughts on what RAID level is appropriate given my use-case, I'd love to hear it! Particularly if anyone knows about RAID1 vs RAID10 on btrfs.

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[–] kaki@sh.itjust.works 5 points 1 day ago* (last edited 1 day ago) (1 children)

I setup BTRFS RAID1 on my NAS recently, here's what I gathered on BTRFS RAID levels:

  • RAID1 vs RAID10:
    • RAID10 theoretically offers better performance (stripping), but the BTRFS implementation isn't well optimized so you don't get that much of a performance boost compared to RAID1.
    • RAID1 may also waste less disk space when using disks of different sizes compared to RAID10, here's a simulator to check: https://www.carfax.org.uk/btrfs-usage/ . In your case it doesn't matter since all your disks are the same size.
  • RAID5/6:
    • It's not only the write-hole, scrubbing is also broken (huge read amplification make performance unusable on large file systems).
    • RAID5/6 is slower than everything else (not a BTRFS problem, it's just parity calculations).
    • I believe the BTRFS developers are getting (relatively) closer to fixing RAID5/6 these days, but they still don't recommend using it. Switching between BTRFS RAID modes can be done pretty easily later without creating a new filesystem, so you could always switch to it later once it's fixed.

In your case, I'd probably use RAID1 or RAID10 for data, and RAID1c3 for metadata.

EDIT: just saw that you don't care that much about losing the data. In that case you don't need any fancy RAID thing, as someone else said just add all your disks in single mode (the default), way simpler and you don't lose any disk space.

[–] GnuLinuxDude@lemmy.ml 1 points 1 day ago

That's a good point about scrubbing on RAID5. I don't think I really want to spend time on that ever. RAID1 at least sounds less complex both in terms of setup and down-the-line maintenance.