On Sun, 3 Jul 2022 13:07:41 -0700, Marc MERLIN [off-list ref] wrote:

Is there any way around this, or not without a full reformat/rebuild?

Hi,
I've been able to change the consistency using mdadm v4.2 on a imsm
container. I don't know if it will work for native metadata. Hope this
helps you a little.

The steps I did it:
1. Stop the volume
# mdadm -S /dev/md/<volume_name>
2. Update to ppl
# mdadm --update-subarray=0 --update=ppl /dev/md/<container_name>
3. Assemble incrementally
# mdadm --incremental /dev/md/<container_name>

Thanks,
Lukasz

gargamel:~# mdadm --query --detail /dev/md5
/dev/md5:
           Version : 1.2
     Creation Time : Tue Jan 21 10:35:52 2014
        Raid Level : raid5
        Array Size : 15627542528 (14903.59 GiB 16002.60 GB)
     Used Dev Size : 3906885632 (3725.90 GiB 4000.65 GB)
      Raid Devices : 5
     Total Devices : 5
       Persistence : Superblock is persistent

     Intent Bitmap : Internal

       Update Time : Sun Jul  3 03:02:01 2022
             State : active, checking 
    Active Devices : 5
   Working Devices : 5
    Failed Devices : 0
     Spare Devices : 0

            Layout : left-symmetric
        Chunk Size : 512K

Consistency Policy : bitmap

      Check Status : 99% complete

              Name : gargamel.svh.merlins.org:5  (local to host
gargamel.svh.merlins.org) UUID : ec672af7:a66d9557:2f00d76c:38c9f705
            Events : 642977

    Number   Major   Minor   RaidDevice State
       0       8      193        0      active sync   /dev/sdm1
       6       8      177        1      active sync   /dev/sdl1
       2       8      209        2      active sync   /dev/sdn1
       3       8        1        3      active sync   /dev/sda1
       5       8       17        4      active sync   /dev/sdb1
gargamel:~# mdadm --grow --consistency-policy=ppl /dev/md5
mdadm: Current consistency policy is bitmap, cannot change to ppl

Kernel 5.16.

Thanks,
Marc
-- 
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- A.S.R. 
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