mount: device or resource busy after enabling multipath
#######################################################

:date: 2013-02-19T23:09:05Z
:category: blog
:tags: linux,heartbeat-cluster
:url: blog/2013/2/19/mount-device-or-resource-busy-after-enabling-multipath.html
:save_as: blog/2013/2/19/mount-device-or-resource-busy-after-enabling-multipath.html
:status: published
:author: Gergely Polonkai

We have a heartbeat cluster with two nodes.  It has been running for several months without
problems.  The shared storage is on an IBM DS3400, on which we have a large volume formatted with
ext4.

Today I decided to reboot the active node for security reasons.  So I’ve switched to the passive
node, which failed at the first step: it was unable to mount the storage (``/dev/sda1``).  After
whining for a few moments, I tried to mount it by hand, which told me

.. code-block:: log

   /dev/sda1 already mounted or /data is busy

I’ve quickly made sure that none of that was true.  After checking this-and-that, it turned out
that the passive node had ``multipathd`` running, so I looked under ``/dev/mapper``, and found two
symlinks there, ``<long-long WWN>`` and ``<long-long WWN>-part1``.  As the partition table and the
disk size was the same as on ``/dev/sda``, I tried to

.. code-block:: shell

   mount /dev/<long-long WWN>-part1 /data

and voilà!  It worked like charm!