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.
Briefly addressing the RAID types you mentioned:
Now, you mentioned not wanting ZFS due to complexity, but really, it is no more complex to manage than BTRFS. It's fairly easy to get it working on any modern Linux distro (Ubuntu has support out-of-the-box, Debian has it packaged as a DKMS module, Arch has it in AUR, and so on).
With ZFS, you could create a RAID-Z1 (equivalent to a RAID-5) without any of the performance penalties or risks that BTRFS RAID-5 has. Both have pretty much them same features, with the main difference that ZFS can't be "re-balanced" to a different disk layout like BTRFS can, but it will also generally not corrupt your data if you look at it wrong. Everything else maps pretty much 1:1 between them. Both support:
Zfs has built-in encryption that can be enabled selectively per dataset, which is handy for some private data.
Also, as long as you avoid raidz, you can now add/remove disks to a pool, and attach/detach mirrors too. That's much more flexible than it used to be.
Too bad raid1 from btrfs has not a zfs equivalent. You can to some extent replicate that via partitioning in zfs, but the simplicity of btrfs raid1 is great for uneven disks.
Has btrfs got its act together with large amounts of snapshots? It used to be a pain point.
My concern with ZFS is I use Fedora, so the kernel updates really frequently. I know that it kicks ass, but I just like having it straightforward in my kernel that I already have installed so that I never have to deal with a
situation. (https://openzfs.github.io/openzfs-docs/Getting%20Started/Fedora/index.html)
Look, there is a reason everyone who actually knows this stuff use ZFS. A good reason. ZFS is really fucking good and BTRFS has absolutely nothing on it. It’s a toy in comparison. ZFS is the gold standard in this class.
You have four sane options:
(Not sure about bit rot recovery when running BTRFS on mdraid. All variants should at least have bit rot detection.)
To reiterate, every storage professional I know has a ZFS-pool at home (and probably everywhere else they can have it, including production pools). They group BTRFS with Ext3, if they even know about it. When I built my home server, the distro and hardware was selected around running ZFS. Distros without good support for ZFS were disregarded right away.