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
