diff --git a/elements/overcloud-partition-uefi/block-device-default.yaml b/elements/overcloud-partition-uefi/block-device-default.yaml
index 515a3dd5d..990316806 100644
--- a/elements/overcloud-partition-uefi/block-device-default.yaml
+++ b/elements/overcloud-partition-uefi/block-device-default.yaml
@@ -19,7 +19,7 @@
         size: 8MiB
       - name: boot
         type: 'BC13C2FF-59E6-4262-A352-B275FD6F7172'
-        size: 500MB
+        size: 500MiB
         mkfs:
           type: ext4
           mount:
@@ -29,7 +29,9 @@
               fsck-passno: 1
       - name: root
         flags: [ boot ]
-        size: 5500MB
+        # The passed-in DIB_IMAGE_SIZE is       6GiB, 6144MiB
+        # Otherwise, there is a 2MiB overhead
+        size: 5618MiB
 - lvm:
     name: lvm
     base: [ root ]
@@ -44,25 +46,27 @@
     lvs:
         - name: lv_root
           base: vg
-          extents: 69%VG
+          # Volume sizes should be a multiple of 4MiB (1 LVM extent)
+          # so this is rounded down from 3706MiB
+          size: 3704MiB
         - name: lv_tmp
           base: vg
-          extents: 4%VG
+          size: 240MiB
         - name: lv_var
           base: vg
-          extents: 15%VG
+          size: 952MiB
         - name: lv_log
           base: vg
-          extents: 4%VG
+          size: 240MiB
         - name: lv_audit
           base: vg
-          extents: 3%VG
+          size: 192MiB
         - name: lv_home
           base: vg
-          extents: 4%VG
+          size: 240MiB
         - name: lv_srv
           base: vg
-          extents: 1%VG
+          size: 48MiB
 - mkfs:
     name: fs_root
     base: lv_root