On Sat, Jun 27, 2020 at 08:06:26PM -0600, Chris Murphy wrote:
Just a PSA: btrfs raid1 does not have a concept of automatic
degraded
mount in the face of a device failure. By default systemd will not
even attempt to mount it if devices are missing. And it's not advised
to use 'degraded' mount option in fstab. If you do need to mount
degraded and later the missing device is found (?) you need to scrub
to catch up the formerly missing device to the current state.
An alternative to raid1 might be lsyncd (Live Syncing Daemon). I use
it to sync my single SSD to a HDD in near-real-time, because doing
raid1 with devices that have different performance characteristics
does not work well (the slower device slows down all writes, even when
using write-behind modes of mdraid).
Or maybe even btrfs send/receive between two separate btrfs
filesystems on the two disks? I have no experience with that (or
btrfs at all really).
I'm cautiously optimistic and would like to see btrfs adopted as the
default due to the huge benefit to having data integrity features (I
run FreeNAS at home for that reason), but I'm honestly a bit scared
off by some of the recent comments in this thread.