Re: flummoxed why I can't umount my md device. fuser and lsof show no files locked

[Roman Mamedov <rm@romanrm.ru>]

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On Mon, 20 Jun 2011 18:48:40 +0100
Simon McNair <simonmcnair@gmail.com> wrote:

> I wanted to run 'mkfs.ext4 -n /dev/md0' to see what settings it would 
> choose that were different to mine but it keeps saying:
> "/dev/md0 is apparently in use by the system; will not make a filesystem 
> here!".
> 
> I also can't stop the array using 'mdadm --stop /dev/md0' as it says 
> mdadm: failed to stop array /dev/md0: Device or resource busy.  pretty 
> much the same error occurs when trying lvchange -an /media/local/Raid
> 
> I've no problem with any of this except I can't find out what process 
> has a handle on the mount and/or why.  so I can't stop/kill it.
> 
> I tried lsof | grep /media/local/Raid and fuser -m /media/local/Raid to 
> no avail.  I also tried ps aux | grep Raid.  I've stopped pretty much 
> everything in init.d including samba,nfs,mediatomb,squeezebox and 
> anything I can think of that I've installed.
> 
> Any advice/ideas please ?

I don't see you mention actually running "umount /media/local/Raid" (and
perhaps listing the error messages you get after that). Perhaps it goes
without saying and you did this, but in case not, remember that "mdadm --stop"
will not try to auto-unmount the filesystem for you first.

Other ideas, AFAIK lsof and fuser won't show you a process that holds the
filesystem mounted in case it doesn't have any files open there, but instead
just has its *current directory* on the FS. So if you launched something while
cd'ed somewhere in /media/local/Raid, and it's still running (maybe the
superuser shell you currently work in?), that'd be your reason.

- 
With respect,
Roman

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