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BTRFS RAID1 has numerous advantages compared to regular RAID1. It does not mirrors whole disks, but chunks of the disk, usually 1GB chunks. This has numerous im

BTRFS RAID1 has numerous advantages compared to regular RAID1. It does not mirrors whole disks, but chunks of the disk, usually 1GB chunks. This has numerous implications: - drive size can be mixed without usable space loss (kind of, with some combinations you end up losing a bit) - you don't need an even number of drives - you don't need a raid0 atop several raid1 to use e.g. 6 drives, it's all one big raid - a drive can be swapped for a bigger or smaller drive without issue, meaning spare drives don't need to be identical etc.

justsomehnguy 5y ago
Just use LVM thin-provisioned RAID1 volume.
matheusmoreira 5y ago
This is such a great feature, it makes it really easy and convenient to expand btrfs arrays. It's such a pity that the parity support is still unstable. Now that ZFS has RAID-Z expansion I don't need to wait anymore.
brnt 5y ago
How would a Btrfs RAID1 array of (equally sized) spinning rust and SSDs work? Will it slow down to the speed of the HDD, or will I get SSD speeds and will the HDD eventually catch up? If not by default, then by option?
- rhn_mk1 5y ago
  For the reading, btrfs currently chooses one of the drives at random, I think based on the PID of the process that's doing the reading. For writing, you have to wait for the slow one.
- etbe 5y ago
  If you want to mix SSD and hard drives then you probably want bcache.