"busy" disk trouble

[Michal Jaegermann]

On Sat, Sep 30, 2006 at 02:32:52AM +0200, ronald wrote:
> Michal Jaegermann wrote:
> >>>??? Neither fuser, nor lsof, nor searches for anything else reveal
> >>>why /dev/sdb1 could be "in use".
> 
> my disk was not accessible caused by a membership in a raid system month 
> ago, but still containing a label/signature from that.
> i could fdisk the drive, but couldn't not swap on it or delete/create 
> partitions/file systems on it.

You were right that problems were caused by dmraid.  This is
a "recycled" disk and I was not even really aware that in the past
it was used in RAID.  It turns out that mkinitrd adds such
disk to dm map and after a boot every partition on such disk
either "does not exist", even if it is there, or is "busy".
All of that without a trace of a hint anywhere why there is a
problem.  Talk about the least surprise!

It is not enough to remove that signature with 'dmraid -r -E ...'
from such disk.  One has to rebuild mkinitrd as well before
that disk becomes accesible.  Does some piece of documentation
even mentions such things?  I am not aware so far.

   Michal