diff --git a/resources/boot.cmd b/resources/boot.cmd
index ad80b1b..d847b0d 100644
--- a/resources/boot.cmd
+++ b/resources/boot.cmd
@@ -1,3 +1,54 @@
+# static config
+setenv boot_partition_a 2
+setenv boot_partition_b 3
+setenv boot_limit 2
+setenv boot_partition_base "/dev/mmcblk0p"
+
+
+# set default values if env not set
+if printenv boot_count; then 
+else 
+  setenv boot_count 1
+fi
+
+if printenv boot_partition; then 
+  # check if valid partition a or b
+  if test ${boot_partition} -ne ${boot_partition_a} && test ${boot_partition} -ne ${boot_partition_b}; then
+    setenv boot_partition ${boot_partition_a}
+  fi
+else 
+  setenv boot_partition ${boot_partition_a}
+fi
+
+
+# switch boot partition if boot count exceed limit
+if test ${boot_count} -ge ${boot_limit}; then
+  echo "!!! Boot limit exceed !!!"
+
+  if test ${boot_partition} -eq ${boot_partition_a}; then
+    setenv boot_partition ${boot_partition_b}
+  else
+    setenv boot_partition ${boot_partition_a}
+  fi
+  setenv boot_count 0
+
+  echo "Switch active partition to ${boot_partition_base}${boot_partition}"
+fi
+
+# increase boot_count
+setexpr boot_count ${boot_count} + 1
+
+# store settings
+saveenv
+
+# load bootargs from pi boot loader
 fdt addr ${fdt_addr} && fdt get value bootargs /chosen bootargs
-ext4load mmc 0:2 ${kernel_addr_r} /boot/uImage
+
+# overwrite boot partition
+setexpr bootargs sub " root=[^ ]+" " root=${boot_partition_base}${boot_partition}" "${bootargs}"
+
+# load kernel and boot
+ext4load mmc 0:${boot_partition} ${kernel_addr_r} /boot/uImage
 bootm ${kernel_addr_r} - ${fdt_addr}
+
+reset
\ No newline at end of file
diff --git a/resources/build.sh b/resources/build.sh
index 15c45bd..de7902b 100755
--- a/resources/build.sh
+++ b/resources/build.sh
@@ -10,14 +10,14 @@ set -e
 : ${TIME_ZONE:="Etc/UTC"}
 : ${HOST_NAME:="alpine"}
 : ${ROOT_PASSWORD:="alpine"}
-: ${IMG_NAME:="alpine-${ALPINE_BRANCH}-sdcard.img"}
+: ${IMG_NAME:="alpine-${ALPINE_BRANCH}-sdcard"}
 
 
 # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 # static config
 # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 RES_PATH=/resources/
-BASE_PACKAGES="alpine-base tzdata parted ifupdown e2fsprogs-extra util-linux coreutils linux-rpi2"
+BASE_PACKAGES="alpine-base tzdata parted ifupdown e2fsprogs-extra util-linux coreutils linux-rpi2 uboot-tools"
 
 WORK_PATH="/work"
 OUTPUT_PATH="/output"
@@ -149,9 +149,59 @@ tmpfs          /tmp         tmpfs  defaults        0     0
 tmpfs          /run         tmpfs  defaults        0     0
 EOF
 
-# custom
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+echo ">> Move persistent data to /data"
+
+# prepare /data
+cat >${ROOTFS_PATH}/etc/local.d/20-data_prepare.start <<EOF
+#!/bin/sh
+mkdir -p /data/root/
+
+mkdir -p /data/dropbear/
+if [ ! -f /data/dropbear/dropbear.conf ]; then
+  cp /etc/conf.d/dropbear_org /data/dropbear/dropbear.conf
+fi
+
+EOF
+chmod +x ${ROOTFS_PATH}/etc/local.d/20-data_prepare.start
+
+# link root dir
+rmdir ${ROOTFS_PATH}/root
+ln -s /data/root ${ROOTFS_PATH}/root
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+
+
+# uboot tools config
+cat >${ROOTFS_PATH}/etc/fw_env.config <<EOF
+/uboot/uboot.env  0x0000          0x4000
+EOF
+
+# TODO REMOVE THIS
+# mark system as booted (should be moved to application)
+cat >${ROOTFS_PATH}/etc/local.d/99-uboot.start <<EOF
+#!/bin/sh
+mount -o remount,rw /uboot
+
+fw_setenv boot_count 1
+
+sync
+mount -o remount,ro /uboot
+EOF
+chmod +x ${ROOTFS_PATH}/etc/local.d/99-uboot.start
+
+# copy helper scripts
+cp ${RES_PATH}/scripts/* ${ROOTFS_PATH}/sbin/
+
+
+# TODO configurable
+# dropbear
 chroot_exec apk add dropbear
 chroot_exec rc-update add dropbear
+ln -s /data/dropbear/ ${ROOTFS_PATH}/etc/dropbear
+
+mv ${ROOTFS_PATH}/etc/conf.d/dropbear ${ROOTFS_PATH}/etc/conf.d/dropbear_org
+ln -s /data/dropbear/dropbear.conf ${ROOTFS_PATH}/etc/conf.d/dropbear
 
 
 rm -rf ${ROOTFS_PATH}/var/cache/apk/*
@@ -259,7 +309,7 @@ image boot.vfat {
   vfat {
     label = "boot"
   }
-  size = 32M
+  size = 100M
 }
 EOF
 make_image ${BOOTFS_PATH} ${WORK_PATH}/genimage_boot.cfg
@@ -315,5 +365,12 @@ image sdcard.img {
 EOF
 make_image ${IMAGE_PATH} ${WORK_PATH}/genimage_sdcard.cfg
 
+echo ">> Compress images"
 # copy final image
-cp ${IMAGE_PATH}/sdcard.img ${OUTPUT_PATH}/${IMG_NAME}
+gzip -c ${IMAGE_PATH}/sdcard.img > ${OUTPUT_PATH}/${IMG_NAME}.img.gz
+gzip -c ${IMAGE_PATH}/rootfs.ext4 > ${OUTPUT_PATH}/${IMG_NAME}_update.img.gz
+
+# create checksums
+cd ${OUTPUT_PATH}/
+sha256sum ${IMG_NAME}.img.gz > ${IMG_NAME}.img.gz.sha256
+sha256sum ${IMG_NAME}_update.img.gz > ${IMG_NAME}_update.img.gz.sha256
diff --git a/resources/resizedata.sh b/resources/resizedata.sh
index 3689938..30e269a 100755
--- a/resources/resizedata.sh
+++ b/resources/resizedata.sh
@@ -1,4 +1,10 @@
 #!/bin/sh -e
+
+# resize already done?
+if [ -f /data/resize_done ]; then
+  return 0
+fi
+
 logger -t "rc.resizedata" "Expanding root partition"
 
 # Detect root partition device
@@ -57,4 +63,4 @@ partprobe /dev/${ROOT_DEV} &&
 
 mount -a
 
-chmod -x /etc/local.d/90-resizedata.start
\ No newline at end of file
+touch /data/resize_done
diff --git a/resources/scripts/ab_active b/resources/scripts/ab_active
new file mode 100755
index 0000000..f6c66ec
--- /dev/null
+++ b/resources/scripts/ab_active
@@ -0,0 +1,11 @@
+ #!/bin/bash
+set -e
+
+# get current partition index
+current_idx=$(rdev | sed 's#/dev/mmcblk0p\([^ ]*\).*#\1#')
+
+if [ $current_idx -eq 2 ]; then
+    echo "Active partition: A"
+else
+    echo "Active partition: B"
+fi
diff --git a/resources/scripts/ab_flash b/resources/scripts/ab_flash
new file mode 100755
index 0000000..034210c
--- /dev/null
+++ b/resources/scripts/ab_flash
@@ -0,0 +1,40 @@
+ #!/bin/bash
+set -e
+
+image_file=$1
+
+if [ -z $image_file ]; then
+    echo "USAGE: $0 [IMAGE_PATH]"
+    return 1
+fi
+
+# change to directory containing update file
+cd $(dirname $image_file)
+
+# check integrity of image
+sha256sum -c ${image_file}.sha256
+
+# get current partition index
+current_idx=$(rdev | sed 's#/dev/mmcblk0p\([^ ]*\).*#\1#')
+
+if [ $current_idx -eq 2 ]; then
+    echo "Start update for partition B"
+    flash_idx=3
+else
+    echo "Start update for partition A"
+    flash_idx=2
+fi
+
+flash_device="/dev/mmcblk0p${flash_idx}"
+
+# flash device
+gunzip -c ${image_file} | dd of=${flash_device} status=progress
+
+
+# switch active partition
+mount -o remount,rw /uboot
+fw_setenv boot_partition ${flash_idx}
+sync
+mount -o remount,ro /uboot
+
+echo "Update complete -> please reboot"