Filesystem setup suggestions?
My BTRFS RAID6 filesystem recently locked up read-only on me, so now I'm redoing my filesystems and am looking for suggestions since I'm not going to go back to BTRFS RAID6. I was on BTRFS before because it allowed the mixed drive sizes, and cannot really afford to get more drives right now to have a proper ZFS setup and still be able to store all my current stuff.
I'm currently trialing UnRAID, but I'm copying stuff from my backups to it and it seems so slow. Through rsync, I'm getting about 50 megabyte/second, and now I'm looking into if there's something else I could be using instead.
I could move back to BTRFS RAID1, but then the whole reason I was on RAID6 BTRFS in the first place was because I was running out of hard drive space and needed some more. One reason I would want to switch back to BTRFS RAID1 is I'd be able to do the easy inplace conversion to RAID5/6 when that is stable again, but I don't know how long that'll be and I'm not sure I want to wait that long.
And then I had the terrible idea of running BTRFS RAID0 on top of MDADM (like a RAID50). I could make 3 arrays, each made of drives of the same size (6TB, 4TB, 3TB). I'd have to look into if BTRFS can properly shrink devices, and this would allow me to shrink/expand in the future, with some work.
Any suggestions, comments, criticism, ideas?
Posted Sep 5, 2016, 8:26 AM UTC
It depends on how much your value the data I suppose. If you have a failure, what is the result? If a drive begins corrupting the array do you want to be able to recover? Are you syncing off site?
I run BTRFS in raid 0. I do this because I have disks at a bunch of different sizes and any other configuration sacrifices too much disk space for my needs. I don't really care if the data survives catastrophe and make sure anything I want to keep isn't only stored on those disks because I know if I lose one I'm toast. That works for me, it might not work for you.
why would you run btrfs on mdadm and not just change the filesystem of each drive to btrfs and add them to a storage pool configured as raid 0 if that is an option?
Well the idea is with mdadm i'd have the drives set up as RAID5 to give me redundancy, but it'll still let me have all the nice things in BTRFS.
How about ZFS on linux or freeNAS?
I don't think ZFS handles different sized drives either. I think I could pool them the same way as I was planning to with mdadm, but last I checked I couldn't just add or remove a single drive in zfs.
You can add single drives, ZFS just wont rebalance the data onto that drive (to make each drive evenly full) which will hurt performance. You'd also be losing redundancy/fault tolerance.
It sounds to me like you don't want/need traditional raid, and just want a pool of drives you can add to as you go, in which case unraid is probably the way to go.
Reliability - Performance - Flexibility, pick 2.