On Tue, Dec 24, 2019 at 2:56 PM Cameron Simpson <cs(a)cskk.id.au> wrote:
Oh yes, one more thing. If you do the RAID1 thing: either make a shiny
new RAID1 and copy to it, or practice the transition with test drives.
Do not risk your high value data by trying to "in place RAID1" it.
I'm not sure if this is even possible with mdadm or lvm. For sure they
have no way of knowing which mirror is correct. But even if it's
possible, it's a bit complicated because it implies repartitioning in
order to make room for the necessary metadata area.
Whereas converting a Btrfs volume from single to raid1 uses balance
code, so it isn't any riskier than a full balance.
--
Chris Murphy