Re: Deleting mdadm RAID arrays

On Wednesday February 6, admin@domeny.pl wrote:

quoted

Maybe the kernel has  been told to forget about the partitions of
/dev/sdb.

But fdisk/cfdisk has no problem whatsoever finding the partitions .

It is looking at the partition table on disk.  Not at the kernel's
idea of partitions, which is initialised from that table...

What does

  cat /proc/partitions

say?

quoted

mdadm will sometimes tell it to do that, but only if you try to
assemble arrays out of whole components.

quoted

If that is the problem, then
   blockdev --rereadpt /dev/sdb

I deleted LVM devices that were sitting on top of RAID and reinstalled mdadm.

% blockdev --rereadpt /dev/sdf
BLKRRPART: Device or resource busy

Implies that some partition is in use.

% mdadm /dev/md2 --fail /dev/sdf1
mdadm: set /dev/sdf1 faulty in /dev/md2

% blockdev --rereadpt /dev/sdf
BLKRRPART: Device or resource busy

% mdadm /dev/md2 --remove /dev/sdf1
mdadm: hot remove failed for /dev/sdf1: Device or resource busy

OK, that's weird.  If sdf1 is faulty, then you should be able to
remove it.  What does
  cat /proc/mdstat
  dmesg | tail

say at this point?

NeilBrown