Thank you for your reply. I did check the source and found the same block, however I’m not familiar enough to understand where I would see this condition indicated? As of now the array seems perfectly normal: https://gist.github.com/jstephenson/0b615aab33bb8157a3876471ef50424e James On Fri, 6 May 2022 at 12:48, Guoqing Jiang <guoqing.jiang@xxxxxxxxx> wrote: > > > > On 5/6/22 6:42 PM, James Stephenson wrote: > > Hi, > > > > First time using this (and indeed any) mailing list, so apologies if I > > violate any etiquette I'm not aware of! > > > > I'm trying to add a write-back journal device to an existing RAID 6 > > array, and it's proving difficult. Essentially I did this: > > > > 1. Put the array in read-only > > 2. Attempt to add a journal device to the array > > 3. md said no because the array has a bitmap > > 4. I tried to remove the bitmap, and it said no: 'md: couldn't update > > array info. -16' > > 5. I rebooted > > 6. The array wouldn't start, and to my surprise was listed as having a > > journal device. Here's what it looked like: > > https://gist.github.com/jstephenson/1db2008c4243c2539d029f1f4706dc14 > > 7. It was _very_ unhappy, and refused to do anything: 'md/raid:md126: > > array cannot have both journal and bitmap' > > 8. The only thing I could do was to zero the superblock on the journal > > device, and then fortunately everything assemble again nicely (with > > bitmap still in place) > > > > So, after a bit of messing around the array is back to where I > > started—RAID 6 with internal bitmap. However, I still cannot remove > > its bitmap. > > > > 1. sudo mdadm --grow /dev/md126 --bitmap=none > > 2. md: couldn't update array info. -16 > > -16 means EBUSY, so probably the array needs resync or recovery per > > https://elixir.bootlin.com/linux/v5.10.106/source/drivers/md/md.c#L7374 > > Thanks, > Guoqing
