how to avoid balance after btrfs replace in raid ?

[DawgG]

i just replaced some old devices in a couple of btrfs-raid-1-systems using the method https://btrfs.wiki.kernel.org/index.php ... le_Devices -> Replacing_Failed_Devices

• 1 umount fs
  2 replace disk
  3 mount in degraded mode
  4 do btrfs replace
  5 done

the first time i formatted the partition on the new device with btrfs, the next time i just used a "raw" partition w/out an fs to replace the old dev/partition with.
in both cases i decided to (had to) rebalance the fs after btrfs replace because

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phobos ~ # btrfs fi df /mnt/backup/
Data, RAID1: total=627.00GiB, used=626.10GiB
Data, single: total=628.00GiB, used=3.50MiB
System, RAID1: total=32.00MiB, used=64.00KiB
System, single: total=64.00MiB, used=128.00KiB
Metadata, RAID1: total=17.00GiB, used=16.79GiB
Metadata, single: total=18.00GiB, used=3.72MiB
GlobalReserve, single: total=512.00MiB, used=0.00B
WARNING: Multiple block group profiles detected, see 'man btrfs(5)'.
WARNING:   Data: single, raid1
WARNING:   Metadata: single, raid1
WARNING:   System: single, raid1

is there a way to avoid this? i was certain the profiles would be inherited from the device still part of the array.
THX for your input!

[Zucca]

Balance basically syncs your data so that in case of raid-1 it ensures you have one copy of each file.
If you remove one drive from the btrfs pool and then balance you will still have intact btrfs pool with one copy redundancy.
If you add one drive to a such pool, you don't need to balance, but you may lose usable space.

If you have lost or removed one drive you need to balance your btrfs or otherwise some files have only single copy.

[DawgG]

THX for your reply.
Reading the link in my initial post i was under the impression that using the "newer" method btrfs replace (instead of first add and second remove) the filesystem on the new device was created using the same profiles as on the replaced device and the still present device (ie all profiles as raid1 at the time of creation) which it obviously is not (hence the warning quoted in my initial post).
i know i have only one copy if i remove one drive from raid1 but i (kind of) expected btrfs replace to fix that in one go replacing the removed drive (ie w/out mandatory balance after replace).