Hi, In my continuing goal to remove the bad blocks log from any of my arrays and not have one on any new arrays I create, I wrote this article: https://strugglers.net/~andy/blog/2020/09/13/debian-installer-mdadm-configuration-and-the-bad-blocks-controversy Shortly afterwards someone on Hacker News¹ said that it is possible to remove the BBL by failing and re-adding devices, like so: # mdadm /dev/md127 --fail /dev/sda --remove /dev/sda --re-add /dev/sda --update=no-bbl I tried that on Ubuntu 18.04: $ mdadm --version mdadm - v4.1-rc1 - 2018-03-22 $ sudo mdadm --fail /dev/md0 /dev/sdb1 --remove /dev/sdb1 --re-add /dev/sdb1 --update=no-bbl mdadm: set /dev/sdb1 faulty in /dev/md0 mdadm: hot removed /dev/sdb1 from /dev/md0 mdadm: --re-add for /dev/sdb1 to /dev/md0 is not possible $ sudo mdadm --add /dev/md0 /dev/sdb1 --update=no-bbl mdadm: --update in Manage mode only allowed with --re-add. $ sudo mdadm --add /dev/md0 /dev/sdb1 mdadm: added /dev/sdb1 $ sudo mdadm --examine-badblocks /dev/sdb1 Bad-blocks list is empty in /dev/sdb1 I tried it on Debian buster: $ mdadm --version mdadm - v4.1 - 2018-10-01 $ sudo mdadm --fail /dev/md6 /dev/sdb1 --remove /dev/sdb1 --re-add /dev/sdb1 --update=no-bbl mdadm: set /dev/sdb1 faulty in /dev/md6 mdadm: hot removed /dev/sdb1 from /dev/md6 mdadm: --re-add for /dev/sdb1 to /dev/md6 is not possible So, is that supposed to work and if so, why doesn't it work for me? In both cases these are simple two device RAID-1 metadata version 1.2 arrays. Neither has bitmaps. Thanks, Andy ¹ https://news.ycombinator.com/item?id=24479235