Hi Gary, On Sat, Sep 26, 2026 at 08:14:02PM -0400, Gary Dale wrote: > The flaw in the logic is that the drive is obviously working as it is part > of a RAID array.
I have tried to explain multiple times that this is not an accurate description. An accurate description is that parts of your drive are in active RAID arrays. That isn't the same as "all of my drive is in a RAID array". Linux can only see I/O errors when it encounters them. If one part of a drive is bad, but it is never read from or written to, Linux will never know. So it is perfectly possible to have an unreadable part of a drive that you can't put into an MD array, but other parts of the drive are in working MD arrays. > What isn't working it getting one partition to rejoin the > array it used to belong to. As far as I was aware this was because you saw in your logs that Linux encountered an I/O error when you tried to do that. > Anyway, a successful write to the partition had no impact. So to elaborate, are you saying that you looked at the logs to find out which sector could not be read, confirmed it could not be read with hdparm (or dd) and then wrote over it with hdparm, as suggested? Or do you mean that you wrote over every sector of the partition in some other way? The reason why I keep saying about confirming if things can be read with other tools is precisely to rule out hardware problems (one or more unreadable sectors). I know you did manage to do a SMART long self-test that came out fine, but if the kernel is reporting an I/O error I still think it would be good to confirm whether that sector is readable generally or not. > There is something about the partition that mdadm doesn't like as evidenced > by the error message: > #mdadm --manage /dev/md0 --add /dev/sda1 > mdadm: add new device failed for /dev/sda1 as 7: Invalid argument > mdadm: Cannot read superblock on /dev/sda1 And when this happens are there any relevant logs in the journal? If there's an I/O error does it mention a sector number? Is it the same sector number every time? Can you read that sector number with other tools? > Either it is in the disk I am trying to add or it is in the array > information. It may be a good time to ask on the linux-raid mailing list. THanks, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting
