diff --git a/casadm/cas_lib.c b/casadm/cas_lib.c
index 94180d2..6233ccf 100644
--- a/casadm/cas_lib.c
+++ b/casadm/cas_lib.c
@@ -254,6 +254,7 @@ static struct name_to_val_mapping cache_mode_names[] = {
 #ifdef WI_AVAILABLE
 	{ .short_name = "wi", .long_name = "Write-Invalidate", .value = ocf_cache_mode_wi },
 #endif
+	{ .short_name = "wo", .long_name = "Write-Only", .value = ocf_cache_mode_wo },
 	{ NULL }
 };
 
@@ -1062,6 +1063,7 @@ int set_cache_mode(unsigned int cache_mode, unsigned int cache_id, int flush)
 	int fd = 0;
 	int orig_mode;
 	struct kcas_set_cache_state cmd;
+	bool flush_param_required;
 
 	fd = open_ctrl_device();
 	if (fd == -1)
@@ -1073,9 +1075,13 @@ int set_cache_mode(unsigned int cache_mode, unsigned int cache_id, int flush)
 		return FAILURE;
 	}
 
-	/* if flushing mode is undefined, set it to default (but only if original mode is write back mode) */
+	/* If flushing mode is undefined, set it to default unless we're transitioning
+	 * out of lazy write cache mode (like WB or WO), in which case user must explicitly
+	 * state his preference */
+	flush_param_required = ocf_mngt_cache_mode_has_lazy_write(orig_mode) &&
+			!ocf_mngt_cache_mode_has_lazy_write(cache_mode);
 	if (-1 == flush) {
-		if (ocf_cache_mode_wb == orig_mode) {
+		if (flush_param_required) {
 			cas_printf(LOG_ERR, "Error: Required parameter (‘--flush-cache’) was not specified.\n");
 			close(fd);
 			return FAILURE;
@@ -1084,14 +1090,15 @@ int set_cache_mode(unsigned int cache_mode, unsigned int cache_id, int flush)
 		}
 	}
 
-	if (ocf_cache_mode_wb == orig_mode) {
+	if (flush_param_required) {
 		if (1 == flush) {
 			cas_printf(LOG_INFO, "CAS is currently flushing dirty data to primary storage devices.\n");
 		} else {
-			cas_printf(LOG_INFO, "CAS is currently migrating from Write-Back to %s mode.\n"
+			cas_printf(LOG_INFO, "CAS is currently migrating from %s to %s mode.\n"
 				"Dirty data are being flushed to primary storage device in background.\n"
 				"Please find flushing progress via list caches command (‘casadm -L’) or\n"
 				"via statistics command (‘casadm -P’).\n",
+				cache_mode_to_name_long(orig_mode),
 				cache_mode_to_name_long(cache_mode));
 		}
 	}
diff --git a/casadm/cas_lib.h b/casadm/cas_lib.h
index 59e17cf..642198c 100644
--- a/casadm/cas_lib.h
+++ b/casadm/cas_lib.h
@@ -125,15 +125,15 @@ int start_cache(ocf_cache_id_t cache_id, unsigned int cache_init,
 int stop_cache(ocf_cache_id_t cache_id, int flush);
 
 #ifdef WI_AVAILABLE
-#define CAS_CLI_HELP_START_CACHE_MODES "wt|wb|wa|pt|wi"
-#define CAS_CLI_HELP_SET_CACHE_MODES "wt|wb|wa|pt|wi"
-#define CAS_CLI_HELP_SET_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Invalidate"
-#define CAS_CLI_HELP_START_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Invalidate"
+#define CAS_CLI_HELP_START_CACHE_MODES "wt|wb|wa|pt|wi|wo"
+#define CAS_CLI_HELP_SET_CACHE_MODES "wt|wb|wa|pt|wi|wo"
+#define CAS_CLI_HELP_SET_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Invalidate, Write-Only"
+#define CAS_CLI_HELP_START_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Invalidate, Write-Only"
 #else
-#define CAS_CLI_HELP_START_CACHE_MODES "wt|wb|wa|pt"
-#define CAS_CLI_HELP_SET_CACHE_MODES "wt|wb|wa|pt"
-#define CAS_CLI_HELP_START_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through"
-#define CAS_CLI_HELP_SET_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through"
+#define CAS_CLI_HELP_START_CACHE_MODES "wt|wb|wa|pt|wo"
+#define CAS_CLI_HELP_SET_CACHE_MODES "wt|wb|wa|pt|wo"
+#define CAS_CLI_HELP_START_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Only"
+#define CAS_CLI_HELP_SET_CACHE_MODES_FULL "Write-Through, Write-Back, Write-Around, Pass-Through, Write-Only"
 #endif
 
 /**
diff --git a/casadm/cas_main.c b/casadm/cas_main.c
index b2a6359..ee8693a 100644
--- a/casadm/cas_main.c
+++ b/casadm/cas_main.c
@@ -900,7 +900,7 @@ int handle_get_param()
 static cli_option set_state_cache_mode_options[] = {
 	{'c', "cache-mode", "Cache mode. Available cache modes: {"CAS_CLI_HELP_SET_CACHE_MODES"}", 1, "NAME", CLI_OPTION_REQUIRED},
 	{'i', "cache-id", CACHE_ID_DESC, 1, "ID", CLI_OPTION_REQUIRED},
-	{'f', "flush-cache", "Flush all dirty data from cache before switching to new mode. Option is required when switching from Write-Back mode", 1, "yes|no",0},
+	{'f', "flush-cache", "Flush all dirty data from cache before switching to new mode. Option is required when switching from Write-Back or Write-Only mode", 1, "yes|no",0},
 	{0},
 };
 
diff --git a/casadm/statistics_model.c b/casadm/statistics_model.c
index 8d24443..d926b4d 100644
--- a/casadm/statistics_model.c
+++ b/casadm/statistics_model.c
@@ -911,9 +911,8 @@ int cache_stats_conf(int ctrl_fd, const struct kcas_cache_info *cache_info,
 		return FAILURE;
 	print_kv_pair(outfile, "Inactive Core Devices", "%d", inactive_cores);
 
-	print_kv_pair(outfile, "Write Policy", "%s%s",
-		      (flush_progress && cache_info->info.cache_mode != ocf_cache_mode_wb)
-		      ? "wb->" : "", cache_mode_to_name(cache_info->info.cache_mode));
+	print_kv_pair(outfile, "Write Policy", "%s",
+		      cache_mode_to_name(cache_info->info.cache_mode));
 	print_kv_pair(outfile, "Eviction Policy", "%s",
 		      eviction_policy_to_name(cache_info->info.eviction_policy));
 	print_kv_pair(outfile, "Cleaning Policy", "%s",
diff --git a/ocf b/ocf
index 75ec3c7..aeaeafb 160000
--- a/ocf
+++ b/ocf
@@ -1 +1 @@
-Subproject commit 75ec3c7db424e11b6e5fbde5f5afba12b824f849
+Subproject commit aeaeafb639ee20f0320ed859efd4a002810f141d
diff --git a/test/smoke_test/basic/12 b/test/smoke_test/basic/12
index bd827ba..8a4ea6c 100755
--- a/test/smoke_test/basic/12
+++ b/test/smoke_test/basic/12
@@ -6,8 +6,7 @@
 
 # The line below specified that line under it should be used as the test's short description when launching test via run_tests script.
 # The text should not be longer than 80 chars - if it is, the script will strip addititonal characters
-# DESCRIPTION WriteBack mode test: Test files on core devices with different filesystems after flushing and stopping cache
-#             with 'don't flush dirty data on exit' option.
+# DESCRIPTION WB data integrity ext3/ext4/xfs after clean shutdown, no flush
 
 # USE_IN_NIGHTLY
 # USE_IN_BVT
@@ -18,6 +17,8 @@ TESTS_DIR="$(dirname $0)/../"
 . $TESTS_DIR/cas_lib
 start_test $*
 
+CACHE_MODE="wb"
+
 # This is where the real test starts
 
 # Use CACHE_DEVICE and CORE_DEVICE provided by configuration file and remove partitions from those devices
@@ -30,15 +31,15 @@ TARGET_DEVICE_OPTION="$CACHE_DEVICE" PARTITION_SIZE_OPTION="2000M" PARTITION_IDS
 TARGET_DEVICE_OPTION="$CORE_DEVICE" PARTITION_SIZE_OPTION="4000M" PARTITION_IDS_OPTION="1 2 3" make_primary_partitions
 
 # Start cache on CACHE_DEVICE1 (/dev/sdd1, for example) with ID=1 and add a core device using CORE_DEVICE1 (/dev/sde1, for example)
-CACHE_ID_OPTION="1" CACHE_DEVICE_OPTION="${CACHE_DEVICE}1" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION="wb" start_cache
+CACHE_ID_OPTION="1" CACHE_DEVICE_OPTION="${CACHE_DEVICE}1" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
 CACHE_ID_OPTION="1" CORE_DEVICE_OPTION="${CORE_DEVICE}1" add_core
 
 # Start cache on CACHE_DEVICE2 (/dev/sdd2, for example) with ID=2 and add a core device using CORE_DEVICE2 (/dev/sde2, for example)
-CACHE_ID_OPTION="2" CACHE_DEVICE_OPTION="${CACHE_DEVICE}2" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION="wb" start_cache
+CACHE_ID_OPTION="2" CACHE_DEVICE_OPTION="${CACHE_DEVICE}2" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
 CACHE_ID_OPTION="2" CORE_DEVICE_OPTION="${CORE_DEVICE}2" add_core
 
 # Start cache on CACHE_DEVICE3 (/dev/sdd3, for example) with ID=3 and add a core device using CORE_DEVICE3 (/dev/sde3, for example)
-CACHE_ID_OPTION="3" CACHE_DEVICE_OPTION="${CACHE_DEVICE}3" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION="wb" start_cache
+CACHE_ID_OPTION="3" CACHE_DEVICE_OPTION="${CACHE_DEVICE}3" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
 CACHE_ID_OPTION="3" CORE_DEVICE_OPTION="${CORE_DEVICE}3" add_core
 
 # Create filesystems on cached devices - we do this using run_cmd because it is not in the API (and probably won't be).
diff --git a/test/smoke_test/basic/13 b/test/smoke_test/basic/13
new file mode 100755
index 0000000..2db81cd
--- /dev/null
+++ b/test/smoke_test/basic/13
@@ -0,0 +1,86 @@
+#!/bin/bash
+#
+# Copyright(c) 2012-2019 Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+#
+
+# The line below specified that line under it should be used as the test's short description when launching test via run_tests script.
+# The text should not be longer than 80 chars - if it is, the script will strip addititonal characters
+# DESCRIPTION WO data integrity ext3/ext4/xfs after clean shutdown, no flush
+
+# USE_IN_NIGHTLY
+# USE_IN_BVT
+# Standard beginning for every test - get the main tests directory and
+# link the cas_lib file for CAS API, then use "start_test $*" to pass params
+# and do other necessary checks and setup
+TESTS_DIR="$(dirname $0)/../"
+. $TESTS_DIR/cas_lib
+start_test $*
+
+CACHE_MODE="wo"
+
+# This is where the real test starts
+
+# Use CACHE_DEVICE and CORE_DEVICE provided by configuration file and remove partitions from those devices
+TARGET_DEVICE_OPTION="$CACHE_DEVICE" remove_partitions
+TARGET_DEVICE_OPTION="$CORE_DEVICE" remove_partitions
+
+# Create 3 primary partitions on CACHE_DEVICE, each of 2000M size
+TARGET_DEVICE_OPTION="$CACHE_DEVICE" PARTITION_SIZE_OPTION="2000M" PARTITION_IDS_OPTION="1 2 3" make_primary_partitions
+# Create 3 primary partitions on CORE_DEVICE, each of 4000M size
+TARGET_DEVICE_OPTION="$CORE_DEVICE" PARTITION_SIZE_OPTION="4000M" PARTITION_IDS_OPTION="1 2 3" make_primary_partitions
+
+# Start cache on CACHE_DEVICE1 (/dev/sdd1, for example) with ID=1 and add a core device using CORE_DEVICE1 (/dev/sde1, for example)
+CACHE_ID_OPTION="1" CACHE_DEVICE_OPTION="${CACHE_DEVICE}1" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
+CACHE_ID_OPTION="1" CORE_DEVICE_OPTION="${CORE_DEVICE}1" add_core
+
+# Start cache on CACHE_DEVICE2 (/dev/sdd2, for example) with ID=2 and add a core device using CORE_DEVICE2 (/dev/sde2, for example)
+CACHE_ID_OPTION="2" CACHE_DEVICE_OPTION="${CACHE_DEVICE}2" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
+CACHE_ID_OPTION="2" CORE_DEVICE_OPTION="${CORE_DEVICE}2" add_core
+
+# Start cache on CACHE_DEVICE3 (/dev/sdd3, for example) with ID=3 and add a core device using CORE_DEVICE3 (/dev/sde3, for example)
+CACHE_ID_OPTION="3" CACHE_DEVICE_OPTION="${CACHE_DEVICE}3" CACHE_FORCE_OPTION="1" CACHE_MODE_OPTION=$CACHE_MODE start_cache
+CACHE_ID_OPTION="3" CORE_DEVICE_OPTION="${CORE_DEVICE}3" add_core
+
+# Create filesystems on cached devices - we do this using run_cmd because it is not in the API (and probably won't be).
+# The test framework will accept invoking the commands directly (e.g. "mkfs.ext3 [...]" without the "run_cmd"), but the
+# results have to be checked manually by the test.
+TARGET_DEVICE_OPTION="${DEVICE_NAME}1-1" FILESYSTEM_TYPE="ext3" make_filesystem
+TARGET_DEVICE_OPTION="${DEVICE_NAME}2-1" FILESYSTEM_TYPE="ext4" make_filesystem
+TARGET_DEVICE_OPTION="${DEVICE_NAME}3-1" FILESYSTEM_TYPE="xfs" make_filesystem
+
+# Specify a temporary file used for md5sums - note that it resides in $TMP_DIR, which is a special directory defined in cas_config.
+# Everytime we use temporary files, they should be placed in that special directory. Its contents are cleared after every test.
+MD5_FILE="$TMP_DIR/cas_md5_sum_"
+
+# Mount the filesystems, then create the example files and save their MD5 sums locally in the temporary place
+# Note the usage of ${MOUNTPOINT} - mount_cache always mounts using following formula: ${MOUNTPOINT}-${CACHE_ID_OPTION}-${CORE_ID_OPTION}.
+for ID in 1 2 3 ; do
+    CACHE_ID_OPTION="$ID" CORE_ID_OPTION="1" mount_cache
+    run_cmd "dd if=/dev/urandom of=${MOUNTPOINT}-${ID}-1/test bs=50M count=1"
+    run_cmd "md5sum ${MOUNTPOINT}-${ID}-1/test > ${MD5_FILE}_${ID}"
+done
+
+# Umount & stop the caches, then mount the core devices
+# Note the usage of ${MOUNTPOINT} - mount_cache always mounts using following formula: ${MOUNTPOINT}-${CACHE_ID_OPTION}-${CORE_ID_OPTION}.
+for ID in 1 2 3 ; do
+    run_cmd "umount ${MOUNTPOINT}-${ID}-1"
+    CACHE_ID_OPTION="$ID" flush_cache
+    CACHE_ID_OPTION="$ID" CACHE_DONT_FLUSH_DATA_OPTION="1" stop_cache
+    run_cmd dd if=/dev/zero of="${CACHE_DEVICE}${ID}" bs=1M count=1 oflag=direct
+    run_cmd "mount ${CORE_DEVICE}${ID} ${MOUNTPOINT}-${ID}-1"
+done
+
+# Now check for files' presence and umount core devices
+# Note the usage of ${MOUNTPOINT} - mount_cache always mounts using following formula: ${MOUNTPOINT}-${CACHE_ID_OPTION}-${CORE_ID_OPTION}.
+for ID in 1 2 3 ; do
+    run_cmd "test -f ${MOUNTPOINT}-${ID}-1/test"
+    run_cmd "md5sum -c ${MD5_FILE}_${ID}"
+    run_cmd "umount ${MOUNTPOINT}-${ID}-1"
+done
+
+# Always return 0 at the end of the test - if at any point something has failed
+# in the API functions, test will end and return a proper result.
+# If you need to check other things during the test and end the test earlier, you
+# should end the test using "end_test $retval" function
+end_test 0
diff --git a/test/smoke_test/cas_functions b/test/smoke_test/cas_functions
index 521ba17..ed65bfd 100644
--- a/test/smoke_test/cas_functions
+++ b/test/smoke_test/cas_functions
@@ -359,7 +359,7 @@ iteration() {
     fi
     if [ -n "$CACHE_MODE_OPTION" ] ; then
         if [ "$CACHE_MODE_OPTION" == "all" ] ; then
-            L_CACHE_MODE_OPTION="wa wb wt pt"
+            L_CACHE_MODE_OPTION="wa wb wt pt wo"
         else
             L_CACHE_MODE_OPTION="$CACHE_MODE_OPTION"
         fi
diff --git a/utils/casadm.8 b/utils/casadm.8
index 36637d3..9bb0eea 100644
--- a/utils/casadm.8
+++ b/utils/casadm.8
@@ -62,6 +62,13 @@ to the core device. Pass-Through mode may be used in case if user doesn't want t
 cache any workload, for example in case if there are some maintenance operations
 causing cache pollution.
 
+.TP
+.B Write-Only (wo)
+In Write-Only mode write operations are handled exactly like in Write-Back mode. Read
+operations do not promote data to cache. Reads are typically serviced by the core
+device, unless corresponding cache lines are dirty.
+
+
 .SH COMMANDS
 .TP
 .B -S, --start-cache
diff --git a/utils/opencas.py b/utils/opencas.py
index 7a9a527..b0e7900 100644
--- a/utils/opencas.py
+++ b/utils/opencas.py
@@ -261,7 +261,7 @@ class cas_config(object):
                         format(self.device))
 
         def check_cache_mode_valid(self, cache_mode):
-            if cache_mode.lower() not in ['wt', 'pt', 'wa', 'wb']:
+            if cache_mode.lower() not in ['wt', 'pt', 'wa', 'wb', 'wo']:
                 raise ValueError('Invalid cache mode {0}'.format(cache_mode))
 
         def check_cleaning_policy_valid(self, cleaning_policy):