On Mon, Mar 27, 2017 at 08:20:39PM -0400, Hendrik Boom wrote: > On Mon, Mar 27, 2017 at 08:06:15PM +0200, [email protected] wrote: > > Boot with the disk with the newest version of /boot, connect/power up > > your disk with the older version of /boot, then add the old partition > > to your md-raid mirror. The "old" partition will be automatically > > updated. Didn't that work ? > > Is it really safe to hotplug a SATA disk?
Yes, SATA is specifically designed for that. > Will Devuan recognise it prperly when I do that? Not only that, but you can also disregard most of the advice in this thread and _not_ zero out signatures on the old disk nor "mdadm -r" the slot. MD RAID is smart enough for that; if it doesn't start the resync automatically you'll have to "mdadm --re-add" but it does have information about how stale the old data is, massively reducing the time needed for resync. When done the naive way (only possibility for a new disk or with slot dropped), every single sector will need to be read and written, which on a modern-sized piece of spinning rust takes ages. The RAID has a write-intent bitmap that marks parts of the disk that have been written to some but not yet all member devices. In your case, the bitmap keeps accumulating[1], but on any typical filesystem load it won't reach all-ones even after many months of degraded use. The write-intent bitmap is not mandatory, and it might be for some reason unfit for use. In such case the RAID will silently fall back to a whole-device resync. Such things are far more fun on btrfs RAID -- it not only knows to avoid resyncing empty space[2], can detect and repair silent read errors, but also can cope with _both_ disks having been mounted in the meantime and having different data written to them. But then, at this point I would recommend _not_ using btrfs RAID unless you know what you're doing. Stick to a single device (which might be MD or HW RAID itself...). Meow! [1]. Which is also a reason you want to turn a [U_] RAID to [U] if the other disk is not going to ever come back, and the replacement has yet to arrive. [2]. That's impossible on MD as it presents only a dumb block device to the filesystem above it, and thus has no knowledge about what is and what is not used. -- ⢀⣴⠾⠻⢶⣦⠀ Meow! ⣾⠁⢠⠒⠀⣿⡁ ⢿⡄⠘⠷⠚⠋⠀ Collisions shmolisions, let's see them find a collision or second ⠈⠳⣄⠀⠀⠀⠀ preimage for double rot13! _______________________________________________ Dng mailing list [email protected] https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
