diff --git a/Makefile b/Makefile
index ed16079ae..ff1779776 100644
--- a/Makefile
+++ b/Makefile
@@ -75,7 +75,7 @@ $(BUILD_DIR)/current_version: $(call depv,CURRENT_VERSION)
 upgrade-versions: $(BUILD_DIR)/upgrade_versions
 $(BUILD_DIR)/upgrade_versions: $(call depv,UPGRADE_VERSIONS)
 	echo -n > $@
-	$(foreach diff,$(UPGRADE_VERSIONS),echo $(diff) >> $@;)
+	$(foreach upgrade_version,$(UPGRADE_VERSIONS),echo $(upgrade_version) >> $@;)
 
 # Macroses for make
 include $(SOURCE_DIR)/rules.mk
diff --git a/config.mk b/config.mk
index 4db60bd1b..a3bc6f063 100644
--- a/config.mk
+++ b/config.mk
@@ -33,38 +33,8 @@ PRODUCT_NAME:=mos
 # to come from DEPS_DIR "as is"
 CURRENT_VERSION:=$(PRODUCT_VERSION)
 
-# This variable is used for building diff repos.
-# If it is not set then diff repo will not be built.
-# If it is set then diff $(BASE_VERSION)->$(CURRENT_VERSION)
-BASE_VERSION:=6.0
-
 PACKAGE_VERSION=6.1.0
-# UPGRADE_VERSIONS?=\
-#	6.0:5.1 \
-#	5.1 \
-#	5.0.3:5.0
-#
-# It means we need to put into a tarball
-#
-# 0) 5.1 -> 6.0   diff mirror and other 6.0   files
-# 1) 5.1          full mirror and other 5.1   files
-# 2) 5.0 -> 5.0.3 diff mirror and other 5.0.3 files
-#
-# * It is prohibited to have multiple bundles for
-# a particular version. E.g. 6.0 bundle can be one of
-#   ** 6.0          full bundle
-#   ** X.Y.Z -> 6.0 diff bundle
-#
-# * If a key (version before colon) is
-# the same as $(CURRENT_VERSION) then
-# a mirror (full or diff) will be built.
-#
-# * If a key does not match $(CURRENT_VERSION) then
-# a mirror (full or diff) is supposed to be
-# available as an artifact from a previous build job.
-#
-UPGRADE_VERSIONS?=\
-	$(CURRENT_VERSION)
+UPGRADE_VERSIONS?=$(CURRENT_VERSION)
 
 # Path to pre-built artifacts
 DEPS_DIR_CURRENT?=$(DEPS_DIR)/$(CURRENT_VERSION)
@@ -80,10 +50,6 @@ DOCKER_ART_NAME?=fuel-images.tar.lrz
 VERSION_YAML_ART_NAME?=version.yaml
 CENTOS_REPO_ART_NAME?=centos-repo.tar
 UBUNTU_REPO_ART_NAME?=ubuntu-repo.tar
-# actual name for a diff repo will be
-# $(DIFF_CENTOS_REPO_ART_BASE)-NEWVERSION-OLDVERSION.tar
-DIFF_CENTOS_REPO_ART_BASE?=diff-centos-repo
-DIFF_UBUNTU_REPO_ART_BASE?=diff-ubuntu-repo
 PUPPET_ART_NAME?=puppet.tgz
 OPENSTACK_YAML_ART_NAME?=openstack.yaml
 TARGET_UBUNTU_IMG_ART_NAME?=ubuntu_target_images.tar
@@ -177,8 +143,6 @@ LOCAL_MIRROR_UBUNTU:=$(LOCAL_MIRROR)/ubuntu
 LOCAL_MIRROR_UBUNTU_OS_BASEURL:=$(LOCAL_MIRROR_UBUNTU)
 LOCAL_MIRROR_DOCKER:=$(LOCAL_MIRROR)/docker
 LOCAL_MIRROR_DOCKER_BASEURL:=$(LOCAL_MIRROR_DOCKER)
-DIFF_MIRROR_CENTOS_BASE:=$(LOCAL_MIRROR)/centos_updates
-DIFF_MIRROR_UBUNTU_BASE:=$(LOCAL_MIRROR)/ubuntu_updates
 
 # Use download.mirantis.com mirror by default. Other possible values are
 # 'msk', 'srt', 'usa', 'hrk'.
diff --git a/mirror/create_diff_mirrors.sh b/mirror/create_diff_mirrors.sh
deleted file mode 100755
index 4623358df..000000000
--- a/mirror/create_diff_mirrors.sh
+++ /dev/null
@@ -1,28 +0,0 @@
-#!/bin/bash
-
-NEWER=$1
-OLDER=$2
-DIFF=$3
-
-# we need to check if OLDER dir exists
-# if not, nothing to compare return exit 1
-test -d ${OLDER} || { echo "${OLDER} path doesn't exist, nothing to compare"; exit 1; }
-
-test -d ${DIFF} || mkdir -p ${DIFF}
-
-function copy_by_checksum (){
-  # compare files by checksum
-  CHECKSUM1=$(md5sum -- $1 | awk '{print $1}')
-  CHECKSUM2=$(md5sum -- $2 | awk '{print $1}')
-
-  # if checksum is different then copy
-  [ $CHECKSUM1 = $CHECKSUM2 ] || cp -av $1 $3
-}
-
-export -f copy_by_checksum
-
-# if file doesn't exists in old, then copy it to diff
-# else compare by checksum
-find ${NEWER} -type f -printf "%f\n" | xargs -i bash -c "test -f ${OLDER}/{} \
-  &&  copy_by_checksum ${NEWER}/{} ${OLDER}/{} ${DIFF} \
-  || cp -av ${NEWER}/{} ${DIFF}/{}"
diff --git a/mirror/diff_mirror_module.mk b/mirror/diff_mirror_module.mk
deleted file mode 100644
index f0e470abc..000000000
--- a/mirror/diff_mirror_module.mk
+++ /dev/null
@@ -1,101 +0,0 @@
-#############################
-# CENTOS DIFF MIRROR ARTIFACT
-#############################
-ifneq ($(BASE_VERSION),)
-.PHONY: centos-diff-repo
-
-DIFF_CENTOS_REPO_ART_NAME:=$(DIFF_CENTOS_REPO_ART_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION).tar
-centos-diff-repo: $(ARTS_DIR)/$(DIFF_CENTOS_REPO_ART_NAME)
-
-$(ARTS_DIR)/$(DIFF_CENTOS_REPO_ART_NAME): $(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME)
-	$(ACTION.COPY)
-
-DIFF_CENTOS_REPO_DEP_FILE:=$(call find-files,$(DEPS_DIR_CURRENT)/$(DIFF_CENTOS_REPO_ART_NAME))
-
-ifneq ($(DIFF_CENTOS_REPO_DEP_FILE),)
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): $(DIFF_CENTOS_REPO_DEP_FILE)
-	$(ACTION.COPY)
-else
-.DELETE_ON_ERROR: $(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME)
-CURRENT_CENTOS_REPO_DEP_FILE:=$(call find-files,$(DEPS_DIR_CURRENT)/$(CENTOS_REPO_ART_NAME))
-ifneq ($(CURRENT_CENTOS_REPO_DEP_FILE),)
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): CURDIR=$(BUILD_DIR)/mirror/$(CURRENT_VERSION)/centos-repo/Packages
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): $(BUILD_DIR)/mirror/centos_repo_current.done
-$(BUILD_DIR)/mirror/centos_repo_current.done: $(CURRENT_CENTOS_REPO_DEP_FILE)
-	mkdir -p $(BUILD_DIR)/mirror/$(CURRENT_VERSION)
-	tar xf $(CURRENT_CENTOS_REPO_DEP_FILE) -C $(BUILD_DIR)/mirror/$(CURRENT_VERSION)
-	$(ACTION.TOUCH)
-else
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): CURDIR=$(LOCAL_MIRROR_CENTOS_OS_BASEURL)/Packages
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): $(BUILD_DIR)/mirror/centos_repo_current.done
-$(BUILD_DIR)/mirror/centos_repo_current.done: \
-		$(BUILD_DIR)/mirror/build.done \
-		$(BUILD_DIR)/packages/build.done \
-		$(BUILD_DIR)/openstack/build.done
-	$(ACTION.TOUCH)
-
-endif
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): BASEDIR=$(BUILD_DIR)/mirror/$(BASE_VERSION)/centos-repo/Packages
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): DIFFDIR=$(DIFF_MIRROR_CENTOS_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION)/Packages
-$(BUILD_DIR)/mirror/$(DIFF_CENTOS_REPO_ART_NAME): | $(LOCAL_MIRROR_CENTOS_OS_BASEURL)/comps.xml
-#	unpacking old version centos mirror
-	mkdir -p $(BUILD_DIR)/mirror/$(BASE_VERSION)
-	tar xf $(DEPS_DIR)/$(BASE_VERSION)/$(CENTOS_REPO_ART_NAME) -C $(BUILD_DIR)/mirror/$(BASE_VERSION)
-#	copying packages which differ from those in base version
-	mkdir -p $(DIFFDIR)
-	/bin/bash $(SOURCE_DIR)/mirror/create_diff_mirrors.sh $(CURDIR) $(BASEDIR) $(DIFFDIR)
-#	creating diff mirror
-	cp $(LOCAL_MIRROR_CENTOS_OS_BASEURL)/comps.xml $(DIFFDIR)/../comps.xml
-	createrepo -g $(DIFFDIR)/../comps.xml -o $(DIFFDIR)/../ $(DIFFDIR)/../
-	rpm -qi -p $(DIFFDIR)/*.rpm | $(SOURCE_DIR)/iso/pkg-versions.awk > $(DIFF_MIRROR_CENTOS_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION)/centos-versions.yaml
-	tar cf $@ -C $(DIFF_MIRROR_CENTOS_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION) --xform s:^:centos_updates-$(CURRENT_VERSION)-$(BASE_VERSION)/: .
-endif # ifneq ($(DIFF_CENTOS_REPO_DEP_FILE),)
-endif # ifneq ($(BASE_VERSION),)
-
-
-#############################
-# UBUNTU DIFF MIRROR ARTIFACT
-#############################
-ifneq ($(BASE_VERSION),)
-.PHONY: ubuntu-diff-repo
-
-DIFF_UBUNTU_REPO_ART_NAME:=$(DIFF_UBUNTU_REPO_ART_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION).tar
-ubuntu-diff-repo: $(ARTS_DIR)/$(DIFF_UBUNTU_REPO_ART_NAME)
-
-$(ARTS_DIR)/$(DIFF_UBUNTU_REPO_ART_NAME): $(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME)
-	$(ACTION.COPY)
-
-DIFF_UBUNTU_REPO_DEP_FILE:=$(call find-files,$(DEPS_DIR_CURRENT)/$(DIFF_UBUNTU_REPO_ART_NAME))
-
-ifneq ($(DIFF_UBUNTU_REPO_DEP_FILE),)
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): $(DIFF_UBUNTU_REPO_DEP_FILE)
-	$(ACTION.COPY)
-else
-.DELETE_ON_ERROR: $(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME)
-CURRENT_UBUNTU_REPO_DEP_FILE:=$(call find-files,$(DEPS_DIR_CURRENT)/$(UBUNTU_REPO_ART_NAME))
-ifneq ($(CURRENT_UBUNTU_REPO_DEP_FILE),)
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): CURDIR=$(BUILD_DIR)/mirror/$(CURRENT_VERSION)/ubuntu-repo
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): $(BUILD_DIR)/mirror/ubuntu_repo_current.done
-$(BUILD_DIR)/mirror/ubuntu_repo_current.done: $(CURRENT_UBUNTU_REPO_DEP_FILE)
-	mkdir -p $(BUILD_DIR)/mirror/$(CURRENT_VERSION)
-	tar xf $(CURRENT_UBUNTU_REPO_DEP_FILE) -C $(BUILD_DIR)/mirror/$(CURRENT_VERSION)
-	$(ACTION.TOUCH)
-else
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): CURDIR=$(LOCAL_MIRROR_UBUNTU_OS_BASEURL)
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): $(BUILD_DIR)/mirror/ubuntu_repo_current.done
-$(BUILD_DIR)/mirror/ubuntu_repo_current.done: \
-		$(BUILD_DIR)/mirror/build.done \
-		$(BUILD_DIR)/packages/build.done \
-		$(BUILD_DIR)/openstack/build.done
-	$(ACTION.TOUCH)
-
-endif
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): BASEDIR=$(BUILD_DIR)/mirror/$(BASE_VERSION)/ubuntu-repo
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME): DIFFDIR=$(DIFF_MIRROR_UBUNTU_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION)
-$(BUILD_DIR)/mirror/$(DIFF_UBUNTU_REPO_ART_NAME):
-	mkdir -p $(DIFFDIR)
-	rsync -av $(CURDIR)/* $(DIFFDIR)
-	zcat $(DIFFDIR)/dists/$(UBUNTU_RELEASE)/main/binary-amd64/Packages.gz | $(SOURCE_DIR)/iso/pkg-versions.awk > $(DIFF_MIRROR_UBUNTU_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION)/ubuntu-versions.yaml
-	tar cf $@ -C $(DIFF_MIRROR_UBUNTU_BASE)-$(CURRENT_VERSION)-$(BASE_VERSION) --xform s:^:ubuntu_updates-$(CURRENT_VERSION)-$(BASE_VERSION)/: .
-endif # ifneq ($(DIFF_UBUNTU_REPO_DEP_FILE),)
-endif # ifneq ($(BASE_VERSION),)
diff --git a/mirror/module.mk b/mirror/module.mk
index fceffa90f..0bc810bea 100644
--- a/mirror/module.mk
+++ b/mirror/module.mk
@@ -11,7 +11,6 @@ clean-mirror:
 include $(SOURCE_DIR)/mirror/centos/module.mk
 include $(SOURCE_DIR)/mirror/ubuntu/module.mk
 include $(SOURCE_DIR)/mirror/docker/module.mk
-include $(SOURCE_DIR)/mirror/diff_mirror_module.mk
 
 $(BUILD_DIR)/mirror/build.done: \
 		$(BUILD_DIR)/mirror/centos/build.done \
diff --git a/upgrade/module.mk b/upgrade/module.mk
index 99c06d0b0..0580f7ffa 100644
--- a/upgrade/module.mk
+++ b/upgrade/module.mk
@@ -73,31 +73,16 @@ endif
 $(BUILD_DIR)/upgrade/openstack_version_$1: $$(ARTS_DIR_$1)/$(OPENSTACK_YAML_ART_NAME)
 	python -c "import yaml; print filter(lambda r: r['fields'].get('name'), yaml.load(open('$$(ARTS_DIR_$1)/$(OPENSTACK_YAML_ART_NAME)')))[0]['fields']['version']" > $$@
 
-ifneq ($2,)
-$(BUILD_DIR)/upgrade/openstack_version_$2: $(DEPS_DIR)/$2/$(OPENSTACK_YAML_ART_NAME)
-	python -c "import yaml; print filter(lambda r: r['fields'].get('name'), yaml.load(open('$(DEPS_DIR)/$2/$(OPENSTACK_YAML_ART_NAME)')))[0]['fields']['version']" > $$@
-endif
-
 $(BUILD_DIR)/upgrade/openstack-part.done: $(BUILD_DIR)/upgrade/openstack-$1-part.done
 
 .DELETE_ON_ERROR: $(BUILD_DIR)/upgrade/openstack-part.tar
 
-ifneq ($2,)
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: CENTOS_REPO_ART=$(DIFF_CENTOS_REPO_ART_BASE)-$1-$2.tar
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: CENTOS_REPO_ART_TOPDIR=centos_updates-$1-$2
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: UBUNTU_REPO_ART=$(DIFF_UBUNTU_REPO_ART_BASE)-$1-$2.tar
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: UBUNTU_REPO_ART_TOPDIR=ubuntu_updates-$1-$2
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: $(BUILD_DIR)/upgrade/openstack_version_$2
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: $$(ARTS_DIR_$1)/$(DIFF_CENTOS_REPO_ART_BASE)-$1-$2.tar
-$(BUILD_DIR)/upgrade/openstack-$1-part.done: $$(ARTS_DIR_$1)/$(DIFF_UBUNTU_REPO_ART_BASE)-$1-$2.tar
-else
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: CENTOS_REPO_ART=$(CENTOS_REPO_ART_NAME)
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: CENTOS_REPO_ART_TOPDIR=centos-repo
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: UBUNTU_REPO_ART=$(UBUNTU_REPO_ART_NAME)
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: UBUNTU_REPO_ART_TOPDIR=ubuntu-repo
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: $$(ARTS_DIR_$1)/$(CENTOS_REPO_ART_NAME)
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: $$(ARTS_DIR_$1)/$(UBUNTU_REPO_ART_NAME)
-endif
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: BASE=$(BUILD_DIR)/upgrade/openstack-$1-part
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: OPENSTACK_VERSION=$$(shell cat $(BUILD_DIR)/upgrade/openstack_version_$1)
 $(BUILD_DIR)/upgrade/openstack-$1-part.done: CENTOS_BASE=$$(BASE)/upgrade/repos/$$(OPENSTACK_VERSION)/centos/x86_64
@@ -119,11 +104,6 @@ $(BUILD_DIR)/upgrade/openstack-$1-part.done: \
 #	OPENSTACK-YAML
 	mkdir -p $$(RELEASES_BASE)
 	cp $$(ARTS_DIR_$1)/$(OPENSTACK_YAML_ART_NAME) $$(RELEASES_BASE)/$$(OPENSTACK_VERSION).yaml
-#	METADATA-YAML
-ifneq ($2,)
-	grep -q "diff_releases:" $(BUILD_DIR)/upgrade/metadata.yaml 2>/dev/null || echo "diff_releases:" > $(BUILD_DIR)/upgrade/metadata.yaml
-	echo "  $$(OPENSTACK_VERSION): $$(shell cat $(BUILD_DIR)/upgrade/openstack_version_$2)" >> $(BUILD_DIR)/upgrade/metadata.yaml
-endif
 #	VERSION-YAML
 	mkdir -p $$(RELEASE_VERSIONS_BASE)
 	cp $$(ARTS_DIR_$1)/$(VERSION_YAML_ART_NAME) $$(RELEASE_VERSIONS_BASE)/$$(OPENSTACK_VERSION).yaml
@@ -134,10 +114,12 @@ endif
 endef
 
 
-$(foreach diff,$(UPGRADE_VERSIONS),$(eval $(call build_openstack_part,$(shell echo $(diff) | awk -F':' '{print $$1}'),$(shell echo $(diff) | awk -F':' '{print $$2}'))))
+$(foreach upgrade_version,$(UPGRADE_VERSIONS),$(eval $(call build_openstack_part,$(upgrade_version))))
 
 
 $(BUILD_DIR)/upgrade/openstack-part.done:
+#   This is for backward compatibility with upgrade script.
+#   It tries to figure out whether a particular update bundle diffirential or not.
 	grep -q "diff_releases:" $(BUILD_DIR)/upgrade/metadata.yaml 2>/dev/null || echo "diff_releases: {}" > $(BUILD_DIR)/upgrade/metadata.yaml
 	tar rf $(BUILD_DIR)/upgrade/openstack-part.tar -C $(BUILD_DIR)/upgrade/ metadata.yaml --xform s:^:upgrade/releases/:
 	$(ACTION.TOUCH)