Cloned from launchpad blueprint https://blueprints.launchpad.net/cinder/+spec/when-deleting-volume-dd-performance.

Description:

I had in trouble in cinder volume deleting.
I am developing for supporting big data storage such as hadoop in lvm .

it use as a full disk io for deleting of cinder lvm volume because of dd
The high disk I/O affects the other hadoop instance on same host. 

So when i delete the volume, i added disk io schduler, ionice

Used in the following way.

     def _copy_volume(self, srcstr, deststr, size_in_g):
-        self._execute('dd', 'if=%s' % srcstr, 'of=%s' % deststr,
+        self._execute('ionice', '-c3', 'dd', 'iflag=direct', 'oflag=direct',
+                      'if=%s' % srcstr, 'of=%s' % deststr,
                       'count=%d' % (size_in_g * 1024), 'bs=1M',
                       run_as_root=True)

Specification URL (additional information):

None