On Thu, Aug 5, 2021 at 4:50 AM José María Terry Jiménez
<jtj(a)tssystems.net> wrote:
El 5/8/21 a las 12:35, François Patte escribió:
Bonjour,
I have a raid-1 array of 2 disks (1 Tb) and I want to replace these disks by 2 2Tb disks.
Just as a point of translation/familiarization/comparison of the same
task with btrfs...
btrfs replace start 1 /dev/sdc /mnt
btrfs replace start 2 /dev/sdd /mnt
btrfs filesystem resize 1:max /mnt
btrfs filesystem resize 2:max /mnt
* btrfs uses a concept of "devid" to keep track of devices; devices
also each have a device item uuid that's totally unambiguous among all
other btrfs file systems, but the devid is unambiguous within a
specific btrfs, unlike /dev/ node which isn't always the same between
reboots.
* use 'btrfs filesystem show' to see devid's
* replace requires the replacement drive is equal to or bigger than
the size of the device being replaced; replace is so much better than
"btrfs device add" followed by "btrfs device remove" (which does file
system resizes automatically) that you're best off shrinking the
source a bit in order to be allowed to use "btrfs replace".
* file system resize is per device, specified by devid; if you don't
specify devid, then devid 1 is assumed
* btrfs replace is derived from the btrfs scrub kernel code, in effect
it makes a virtual and temporary "mirror" between the to-be-replaced
device and replacement device, and does a scrub to quickly replicate
in-use blocks from source to destination.
* btrfs replace works with non-raid profiles, including live migration
from a single drive to a new drive
* you can use 'btrfs replace' even if the drive is missing, even if
you're mounted degraded
* writes go to both the replacee and replacement devices
* following crash/power fail the replace will resume
* reminder that there's a built-in shortcut for all btrfs commands,
you don't need to configure it or set it up; as long as you enter an
unambiguous command, it'll be accepted, if you enter something
ambiguous, it'll make suggestions:
$ sudo btrfs rep sta
btrfs replace: ambiguous token 'sta'
Did you mean one of these ?
start
status
'btrfs rep star' is unambiguous for 'btrfs replace start' - just make
up your own short hand...
--
Chris Murphy