Deprecate the block_device driver

The BlockDevice Driver continues to be behind,
and not tested very well; and adoption doesn't
appear to be that significant.

The only argument to having/keeping it in the past
has been that it was required for performance, however
most recent data analysis using the LIO driver and LVM
(standard reference driver) seems to indicate that there
in fact may not be a significant performance difference.

Additionally, if higher performance is desired, using a
striping across multiple disks with the LVM reference
drivers will provide higher performance.

Closes-Bug: #1642441
DocImpact

Change-Id: Ic5f8c49e9c707a812cd0dc1d99b1e46a06c60015

cinder/volume/drivers/block_device.py

@@ -17,6 +17,7 @@ import os
 
 from oslo_config import cfg
 from oslo_log import log as logging
+from oslo_log import versionutils
 from oslo_utils import importutils
 from oslo_utils import units
 
@@ -50,9 +51,17 @@ class BlockDeviceDriver(driver.BaseVD, driver.LocalVD,
 
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "Cinder_Jenkins"
+    SUPPORTED = False
 
     def __init__(self, *args, **kwargs):
         super(BlockDeviceDriver, self).__init__(*args, **kwargs)
+        # This driver has been marked as deprecated in the Ocata release, as
+        # per the standard OpenStack deprecation policy it can be removed in
+        # the Queens release.
+        msg = _("The block_device driver is deprecated and will be "
+                "removed in a future release.")
+        versionutils.report_deprecated_feature(LOG, msg)
+
         self.configuration.append_config_values(volume_opts)
         self.backend_name = \
             self.configuration.safe_get('volume_backend_name') or "BlockDev"

releasenotes/notes/deprecate-block-device-driver-d30232547a31fe1e.yaml

@@ -0,0 +1,6 @@
+---
+deprecations:
+  - The block_driver is deprecated as of the Ocata release and will be
+    removed in the Queens release of Cinder.  Instead the LVM driver
+    with the LIO iSCSI target should be used.  For those that desire
+    higher performance, they should use LVM striping.