Optimize the dd command to improve performance

Use if=/dev/zero: Instead of reading from /dev/urandom,
which is slow for generating random data, use /dev/zero
to write zeros to the disk. Zeros are generated much faster.
Omit conv=fsync: The conv=fsync option forces dd to
synchronize the data after each write, which can be slow for
large writes.

Change-Id: Id845c60c39072a03171fa5906461eb254c2736a7

manila_tempest_tests/config.py

@@ -336,4 +336,17 @@ ShareGroup = [
                      "attempt to create an IPv6 subnet on the project network "
                      "they create for ping and SSH to the client test VM "
                      "where data path testing is performed."),
+    cfg.StrOpt("dd_input_file",
+               default="/dev/zero",
+               help="The input file (if) in the dd command specifies the "
+                    "source of data that dd will read and process, which can "
+                    "be a device, a regular file, or even standard input "
+                    "(stdin). dd copies, transforms, or performs actions on "
+                    "this data based on provided options and then writes it "
+                    "to an output file or device (of). When using /dev/zero "
+                    "in storage systems with default compression, although "
+                    "it generates highly compressible null bytes (zeros), "
+                    "writing data from /dev/zero might not yield significant "
+                    "space savings as these systems are already optimized for "
+                    "efficient compression."),
 ]

manila_tempest_tests/tests/scenario/manager_share.py

@@ -229,8 +229,7 @@ class ShareScenarioTest(manager.NetworkScenarioTest):
     def write_data_to_mounted_share_using_dd(self, remote_client,
                                              output_file,
                                              block_size,
-                                             block_count,
+                                             block_count):
-                                             input_file='/dev/zero'):
         """Writes data to mounted share using dd command
 
         Example Usage for writing 512Mb to a file on /mnt/
@@ -243,13 +242,12 @@ class ShareScenarioTest(manager.NetworkScenarioTest):
         :param block_size: The size of an individual block in bytes
         :param block_count: The number of blocks to write
         :param output_file: Path to the file to be written
-        :param input_file: Path to the file to read from
         """
         block_count = int(block_count)
         remote_client.exec_command(
-            "sudo sh -c \"dd bs={} count={} if={} of={} conv=fsync"
+            "sudo sh -c \"dd bs={} count={} if={} of={} iflag=fullblock\""
-            " iflag=fullblock\""
+            .format(block_size, block_count, CONF.share.dd_input_file,
-            .format(block_size, block_count, input_file, output_file))
+                    output_file))
 
     def read_data_from_mounted_share(self,
                                      remote_client,

manila_tempest_tests/tests/scenario/test_share_extend.py

@@ -76,8 +76,7 @@ class ShareExtendBase(manager.ShareScenarioTest):
                   .format(three_quarter_blocks))
         self.write_data_to_mounted_share_using_dd(remote_client,
                                                   '/mnt/t1', '64M',
-                                                  three_quarter_blocks,
+                                                  three_quarter_blocks)
-                                                  '/dev/urandom')
         ls_result = remote_client.exec_command("sudo ls -lAh /mnt/")
         LOG.debug(ls_result)
 
@@ -86,8 +85,7 @@ class ShareExtendBase(manager.ShareScenarioTest):
         self.assertRaises(
             exceptions.SSHExecCommandFailed,
             self.write_data_to_mounted_share_using_dd,
-            remote_client, '/mnt/t2', '64M', over_one_quarter_blocks,
+            remote_client, '/mnt/t2', '64M', over_one_quarter_blocks)
-            '/dev/urandom')
         ls_result = remote_client.exec_command("sudo ls -lAh /mnt/")
         LOG.debug(ls_result)
 
@@ -129,8 +127,7 @@ class ShareExtendBase(manager.ShareScenarioTest):
             self.write_data_to_mounted_share_using_dd(remote_client,
                                                       output_file,
                                                       block_size,
-                                                      block_count,
+                                                      block_count)
-                                                      '/dev/urandom')
         except exceptions.SSHExecCommandFailed as e:
             if 'stale file handle' in str(e).lower():
                 LOG.warning("Client was disconnected during extend process")
@@ -139,8 +136,7 @@ class ShareExtendBase(manager.ShareScenarioTest):
                 self.write_data_to_mounted_share_using_dd(remote_client,
                                                           output_file,
                                                           block_size,
-                                                          block_count,
+                                                          block_count)
-                                                          '/dev/urandom')
             else:
                 raise
 

manila_tempest_tests/tests/scenario/test_share_manage_unmanage.py

@@ -105,7 +105,7 @@ class ShareManageUnmanageBase(manager.ShareScenarioTest):
         LOG.debug('Step 6b - writing 640mb')
         self.write_data_to_mounted_share_using_dd(remote_client,
                                                   '/mnt/t1', 1024,
-                                                  2048, '/dev/zero')
+                                                  2048)
         ls_result = remote_client.exec_command("sudo ls -lA /mnt/")
         LOG.debug(ls_result)
 

manila_tempest_tests/tests/scenario/test_share_shrink.py

@@ -79,7 +79,7 @@ class ShareShrinkBase(manager.ShareScenarioTest):
         LOG.debug('Step 6 - writing {} * 64MB blocks'.format(blocks))
         self.write_data_to_mounted_share_using_dd(remote_client,
                                                   '/mnt/t1', '64M',
-                                                  blocks, '/dev/urandom')
+                                                  blocks)
         ls_result = remote_client.exec_command("sudo ls -lAh /mnt/")
         LOG.debug(ls_result)
 
@@ -120,7 +120,7 @@ class ShareShrinkBase(manager.ShareScenarioTest):
         self.assertRaises(
             exceptions.SSHExecCommandFailed,
             self.write_data_to_mounted_share_using_dd,
-            remote_client, '/mnt/t1', '64M', blocks, '/dev/urandom')
+            remote_client, '/mnt/t1', '64M', blocks)
 
         LOG.debug('Step 12 - unmount')
         self.unmount_share(remote_client)

zuul.d/manila-tempest-jobs.yaml

@@ -157,6 +157,7 @@
               backend_names: LONDON,PARIS
               multi_backend: true
               image_password: manila
+              dd_input_file: /dev/urandom
 
 - job:
     name: manila-tempest-plugin-zfsonlinux