diff --git a/usr/share/rear/conf/GNU/Linux.conf b/usr/share/rear/conf/GNU/Linux.conf

index 5b9343b9..f0c44381 100644

--- a/usr/share/rear/conf/GNU/Linux.conf

+++ b/usr/share/rear/conf/GNU/Linux.conf

@@ -184,6 +184,8 @@ env

 w

 dosfslabel

 sysctl

+blockdev

+lsblk

 )

 # the lib* serves to cover both 32bit and 64bit libraries!

diff --git a/usr/share/rear/lib/layout-functions.sh b/usr/share/rear/lib/layout-functions.sh

index eb45115b..af1069ea 100644

--- a/usr/share/rear/lib/layout-functions.sh

+++ b/usr/share/rear/lib/layout-functions.sh

@@ -365,7 +365,9 @@ get_partition_start() {

     local disk_name=$1

     local start_block start

-    local block_size=$(get_block_size ${disk_name%/*})

+    # When reading /sys/block/.../start or "dmsetup table", output is always in

+    # 512 bytes blocks

+    local block_size=512

     if [[ -r /sys/block/$disk_name/start ]] ; then

         start_block=$(< $path/start)

@@ -548,11 +550,32 @@ get_device_mapping() {

 }

 # Get the size in bytes of a disk/partition.

+# For disks, use "sda" as argument.

 # For partitions, use "sda/sda1" as argument.

 get_disk_size() {

     local disk_name=$1

+    # When a partition is specified (e.g. sda/sda1)

+    # then it has to read /sys/block/sda/sda1/size in the old code below.

+    # In contrast the get_block_size() function below is different

+    # because it is non-sense asking for block size of a partition,

+    # so that the get_block_size() function below is stripping everything

+    # in front of the blockdev basename (e.g. /some/path/sda -> sda)

+    # cf. https://github.com/rear/rear/pull/1885#discussion_r207900308

+

+    # Preferably use blockdev, see https://github.com/rear/rear/issues/1884

+    if has_binary blockdev; then

+        # ${disk_name##*/} translates 'sda/sda1' into 'sda1' and 'sda' into 'sda'

+        blockdev --getsize64 /dev/${disk_name##*/} && return

+        # If blockdev fails do not error out but fall through to the old code below

+        # because blockdev fails e.g. for a CDROM device when no DVD or ISO is attached to

+        # cf. https://github.com/rear/rear/pull/1885#issuecomment-410676283

+        # and https://github.com/rear/rear/pull/1885#issuecomment-410697398

+    fi

-    local block_size=$(get_block_size ${disk_name%/*})

+    # Linux always considers sectors to be 512 bytes long. See the note in the

+    # kernel source, specifically, include/linux/types.h regarding the sector_t

+    # type for details.

+    local block_size=512

     retry_command test -r /sys/block/$disk_name/size || Error "Could not determine size of disk $disk_name"

@@ -565,9 +588,20 @@ get_disk_size() {

 # Get the block size of a disk.

 get_block_size() {

+    local disk_name="${1##*/}" # /some/path/sda -> sda

+

+    # Preferably use blockdev, see https://github.com/rear/rear/issues/1884

+    if has_binary blockdev; then

+        blockdev --getss /dev/$disk_name && return

+        # If blockdev fails do not error out but fall through to the old code below

+        # because blockdev fails e.g. for a CDROM device when no DVD or ISO is attached to

+        # cf. https://github.com/rear/rear/pull/1885#issuecomment-410676283

+        # and https://github.com/rear/rear/pull/1885#issuecomment-410697398

+    fi

+

     # Only newer kernels have an interface to get the block size

-    if [ -r /sys/block/$1/queue/logical_block_size ] ; then

-        echo $( < /sys/block/$1/queue/logical_block_size)

+    if [ -r /sys/block/$disk_name/queue/logical_block_size ] ; then

+        echo $( < /sys/block/$disk_name/queue/logical_block_size)

     else

         echo "512"

     fi