diff --git a/Create.c b/Create.c
index c96b319..1fb4043 100644
--- a/Create.c
+++ b/Create.c
@@ -234,8 +234,15 @@ int Create(struct supertype *st, char *mddev,
 	case 10:
 	case 6:
 	case 0:
-	case LEVEL_LINEAR: /* linear */
 		if (chunk == 0) {
+			chunk = 512;
+			if (verbose > 0)
+				fprintf(stderr, Name ": chunk size defaults to 512K\n");
+		}
+		break;
+	case LEVEL_LINEAR:
+		/* a chunksize of zero 0s perfectly valid (and preferred) since 2.6.16 */
+		if (get_linux_version() < 2006016 && chunk == 0) {
 			chunk = 64;
 			if (verbose > 0)
 				fprintf(stderr, Name ": chunk size defaults to 64K\n");
diff --git a/mdadm.8 b/mdadm.8
index 121fc29..2df353c 100644
--- a/mdadm.8
+++ b/mdadm.8
@@ -440,7 +440,9 @@ before the number of devices in the array is reduced.
 
 .TP
 .BR \-c ", " \-\-chunk=
-Specify chunk size of kibibytes.  The default is 64.
+Specify chunk size of kibibytes.  The default when creating an
+array is 512KB.  To ensure compatibility with earlier versions, the
+default when Building and array with no persistent metadata is 64KB.
 This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10.
 
 .TP
@@ -450,7 +452,8 @@ component will be rounded down to a multiple of this size.
 This is a synonym for
 .B \-\-chunk
 but highlights the different meaning for Linear as compared to other
-RAID levels.
+RAID levels.  The default is 64K if a kernel earlier than 2.6.16 is in
+use, and is 0K (i.e. no rounding) in later kernels.
 
 .TP
 .BR \-l ", " \-\-level=
diff --git a/tests/00linear b/tests/00linear
index ec6a166..d0791c1 100644
--- a/tests/00linear
+++ b/tests/00linear
@@ -3,13 +3,13 @@
 
 mdadm -CR $md0 -l linear -n3 $dev0 $dev1 $dev2
 check linear
-testdev $md0 3 $mdsize0 64 
+testdev $md0 3 $mdsize0 1
 mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 --level=linear -n4 $dev0 $dev1 $dev2 $dev3
 check linear
-testdev $md0 4 $mdsize1 64 
+testdev $md0 4 $mdsize1 1
 mdadm -S $md0
 
 # now with no superblock
diff --git a/tests/00raid0 b/tests/00raid0
index f5122ec..8c3dfc3 100644
--- a/tests/00raid0
+++ b/tests/00raid0
@@ -3,19 +3,19 @@
 
 mdadm -CR $md0 -l raid0 -n3 $dev0 $dev1 $dev2 
 check raid0
-testdev $md0 3 $mdsize0 64 
+testdev $md0 3 $mdsize0 512 
 mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 -l0 -n4 $dev0 $dev1 $dev2 $dev3 
 check raid0
-testdev $md0 4 $mdsize1 64 
+testdev $md0 4 $mdsize1 512 
 mdadm -S $md0
 
 # now with no superblock
 mdadm -B $md0 -l0 -n5 $dev0 $dev1 $dev2 $dev3 $dev4 
 check raid0
-testdev $md0 5 $size 64
+testdev $md0 5 $size 512
 mdadm -S $md0
 
 
diff --git a/tests/00raid10 b/tests/00raid10
index 6fffb74..283bfcd 100644
--- a/tests/00raid10
+++ b/tests/00raid10
@@ -13,6 +13,6 @@ do
  esac
  mdadm --create --run --level=raid10 --layout $lo --raid-disks 6 -x 1 $md0 $devs
  check resync ; check raid10
- testdev $md0 $m $mdsize0 $[64*cm]
+ testdev $md0 $m $mdsize0 $[512*cm]
  mdadm -S $md0
 done
diff --git a/tests/00raid4 b/tests/00raid4
index ddb16b1..fa6eab5 100644
--- a/tests/00raid4
+++ b/tests/00raid4
@@ -3,13 +3,13 @@
 
 mdadm -CfR $md0 -l 4 -n3 $dev0 $dev1 $dev2 
 check resync ; check raid[45]
-testdev $md0 2 $mdsize0 64
+testdev $md0 2 $mdsize0 512
 mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 --level=raid4 -n4 $dev0 $dev1 $dev2 $dev3 
 check recovery; check raid[45]
-testdev $md0 3 $mdsize1 64
+testdev $md0 3 $mdsize1 512
 mdadm -S $md0
 
 
diff --git a/tests/00raid5 b/tests/00raid5
index 71f3654..0caf935 100644
--- a/tests/00raid5
+++ b/tests/00raid5
@@ -3,13 +3,13 @@
 
 mdadm -CfR $md0 -l 5 -n3 $dev0 $dev1 $dev2 
 check resync
-testdev $md0 2 $mdsize0 64
+testdev $md0 2 $mdsize0 512
 mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 --level=raid5 -n4 $dev0 $dev1 $dev2 $dev3 
 check recovery
-testdev $md0 3 $mdsize1 64
+testdev $md0 3 $mdsize1 512
 mdadm -S $md0
 
 # now same again with explicit layout
@@ -19,13 +19,13 @@ do
 
   mdadm -CfR $md0  -l 5 -p $lo -n3 $dev0 $dev1 $dev2 
   check resync ; check raid5
-  testdev $md0 2 $mdsize0 64
+  testdev $md0 2 $mdsize0 512
   mdadm -S $md0
 
   # now with version-1 superblock
   mdadm -CR $md0 -e1 --level=raid5 --layout $lo -n4 $dev0 $dev1 $dev2 $dev3 
   check recovery ; check raid5
-  testdev $md0 3 $mdsize1 64
+  testdev $md0 3 $mdsize1 512
   mdadm -S $md0
 
 done
diff --git a/tests/00raid6 b/tests/00raid6
index 81834aa..4b293e2 100644
--- a/tests/00raid6
+++ b/tests/00raid6
@@ -3,13 +3,13 @@
 
 mdadm -CfR $md0 -l 6 -n4 $dev0 $dev1 $dev2 $dev3 
 check resync ; check raid6
-testdev $md0 2 $mdsize0 64
+testdev $md0 2 $mdsize0 512
 mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 --level=raid6 -n5 $dev0 $dev1 $dev2 $dev3 $dev4 
 check resync ; check raid6
-testdev $md0 3 $mdsize1 64
+testdev $md0 3 $mdsize1 512
 mdadm -S $md0
 
 
diff --git a/tests/02lineargrow b/tests/02lineargrow
index 78477a3..3f7c1a9 100644
--- a/tests/02lineargrow
+++ b/tests/02lineargrow
@@ -10,13 +10,13 @@ do
 	1.2 ) sz=$mdsize12 ;;
   esac
   mdadm -CRf $md0 --level linear -e $e --raid-disks=1 $dev1
-  testdev $md0 1 $sz 64
+  testdev $md0 1 $sz 1
 
   mdadm --grow $md0 --add $dev2
-  testdev $md0 2 $sz 64
+  testdev $md0 2 $sz 1
 
   mdadm --grow $md0 --add $dev3
-  testdev $md0 3 $sz 64
+  testdev $md0 3 $sz 1
 
   mdadm -S $md0
 done
diff --git a/tests/02r5grow b/tests/02r5grow
index 2247570..0b46f60 100644
--- a/tests/02r5grow
+++ b/tests/02r5grow
@@ -10,11 +10,11 @@ testdev $md0 2 $[size/2] 32
 mdadm --grow $md0 --size max
 check resync
 check wait
-testdev $md0 2 $mdsize0 64
+testdev $md0 2 $mdsize0 32
 
 mdadm --grow $md0 --size $[size/2]
 check nosync
-testdev $md0 2 $[size/2] 64
+testdev $md0 2 $[size/2] 32
 
 mdadm -S $md0
 
diff --git a/tests/02r6grow b/tests/02r6grow
index cdcc46a..1a7042c 100644
--- a/tests/02r6grow
+++ b/tests/02r6grow
@@ -10,11 +10,11 @@ testdev $md0 2 $[size/2] 32
 mdadm --grow $md0 --size max
 check resync
 check wait
-testdev $md0 2 $mdsize0 64
+testdev $md0 2 $mdsize0 32
 
 mdadm --grow $md0 --size $[size/2]
 check nosync
-testdev $md0 2 $[size/2] 64
+testdev $md0 2 $[size/2] 32
 
 mdadm -S $md0
 
diff --git a/tests/03r0assem b/tests/03r0assem
index 55205a3..10e2a66 100644
--- a/tests/03r0assem
+++ b/tests/03r0assem
@@ -6,7 +6,7 @@
 
 mdadm -CR $md2 -l0 -n3 $dev0 $dev1 $dev2 
 check raid0
-tst="testdev $md2 3 $mdsize0 64"
+tst="testdev $md2 3 $mdsize0 512"
 $tst
 uuid=`mdadm -Db $md2 | sed 's/.*UUID=//'`
 mdadm -S $md2
@@ -70,7 +70,7 @@ mdadm -S $md2
 mdadm --zero-superblock $dev0 $dev1 $dev2
 mdadm -CR $md2 -l0 --metadata=1.0 -n3 $dev0 $dev1 $dev2 
 check raid0
-tst="testdev $md2 3 $mdsize1 64"
+tst="testdev $md2 3 $mdsize1 512"
 $tst
 
 uuid=`mdadm -Db $md2 | sed 's/.*UUID=//'`
diff --git a/tests/03r5assem b/tests/03r5assem
index be26cf1..585170f 100644
--- a/tests/03r5assem
+++ b/tests/03r5assem
@@ -3,7 +3,7 @@
 # including with missing devices.
 
 mdadm -CR $md1 -l5 -n3 $dev0 $dev1 $dev2 
-tst="check raid5 ;testdev $md1 2 $mdsize0 64 ; mdadm -S $md1"
+tst="check raid5 ;testdev $md1 2 $mdsize0 512 ; mdadm -S $md1"
 uuid=`mdadm -Db $md1 | sed 's/.*UUID=//'`
 check wait
 eval $tst
diff --git a/tests/03r5assemV1 b/tests/03r5assemV1
index 0f2c83b..5238ede 100644
--- a/tests/03r5assemV1
+++ b/tests/03r5assemV1
@@ -2,7 +2,7 @@
 # create a v-1 raid5 array and assemble in various ways
 
 mdadm -CR -e1 --name one $md1 -l5 -n3 -x2 $dev0 $dev1 $dev2 $dev3 $dev4
-tst="check raid5 ;testdev $md1 2 $mdsize1 64 ; mdadm -S $md1"
+tst="check raid5 ;testdev $md1 2 $mdsize1 512 ; mdadm -S $md1"
 uuid=`mdadm -Db $md1 | sed 's/.*UUID=//'`
 check wait
 
diff --git a/tests/04r0update b/tests/04r0update
index 23c7d65..e13645b 100644
--- a/tests/04r0update
+++ b/tests/04r0update
@@ -1,7 +1,7 @@
 
 # create a raid0, re-assemble with a different super-minor
 mdadm -CR $md0 -l0 -n3 $dev0 $dev1 $dev2 
-testdev $md0 3 $mdsize0 64
+testdev $md0 3 $mdsize0 512
 minor1=`mdadm -E $dev0 | sed -n -e 's/.*Preferred Minor : //p'`
 mdadm -S /dev/md0
 
diff --git a/tests/07autoassemble b/tests/07autoassemble
index bdbc5d3..be3d993 100644
--- a/tests/07autoassemble
+++ b/tests/07autoassemble
@@ -10,7 +10,7 @@ mdadm -Ss
 mdadm -As -c /dev/null --homehost=testing -vvv
 testdev $md1 1 $mdsize0 64
 testdev $md2 1 $mdsize0 64
-testdev $md0 2 $mdsize00 64
+testdev $md0 2 $mdsize00 512
 mdadm -Ss
 
 mdadm --zero-superblock $dev0 $dev1 $dev2 $dev3
@@ -20,5 +20,5 @@ mdadm -CR $md0 -l0 -n2 $md1 $dev2  --homehost=testing
 mdadm -Ss
 mdadm -As -c /dev/null --homehost=testing -vvv
 testdev $md1 1 $mdsize0 64
-testdev $md0 1 $[mdsize0+mdsize00] 64
+testdev $md0 1 $[mdsize0+mdsize00] 512
 mdadm -Ss
diff --git a/tests/07changelevels b/tests/07changelevels
index af27918..633798d 100644
--- a/tests/07changelevels
+++ b/tests/07changelevels
@@ -89,10 +89,10 @@ mdadm $md0 --fail $dev3
 # switch layout to a DDF layout and back to make sure that works.
 
 mdadm -G /dev/md0 --layout=ddf-N-continue --backup-file $bu
-checkgeo md0 raid6 4 $[64*1024] 10
+checkgeo md0 raid6 4 $[512*1024] 10
 dotest 2
 mdadm -G /dev/md0 --layout=ra --backup-file $bu
-checkgeo md0 raid6 4 $[64*1024] 1
+checkgeo md0 raid6 4 $[512*1024] 1
 dotest 2
 
 mdadm -G $md0 -l5 --backup-file $bu
diff --git a/tests/07layouts b/tests/07layouts
index c0c9ea0..91baec0 100644
--- a/tests/07layouts
+++ b/tests/07layouts
@@ -12,7 +12,7 @@ export MDADM_GROW_VERITY=1
 dotest() {
  sleep 0.5
  check wait
- testdev $md0 $1 $mdsize0 64 nd
+ testdev $md0 $1 $mdsize0 512 nd
  blockdev --flushbufs $md0
  cmp -s -n $[textK*1024] $md0 /tmp/RandFile || { echo cmp failed; exit 2; }
  # write something new - shift chars 4 space
@@ -59,7 +59,7 @@ l5[5]=parity-last
 for layout in 0 1 2 3 4 5 0
 do
  mdadm -G $md0 --layout=${l5[$layout]} --backup-file $bu
- checkgeo md0 raid5 5 $[64*1024] $layout
+ checkgeo md0 raid5 5 $[512*1024] $layout
  dotest 4
 done
 
@@ -86,6 +86,6 @@ l6[20]=parity-first-6
 for layout in 0 1 2 3 4 5 8 9 10 16 17 18 19 20 0
 do
  mdadm -G $md0 --layout=${l6[$layout]} --backup-file $bu
- checkgeo md0 raid6 5 $[64*1024] $layout
+ checkgeo md0 raid6 5 $[512*1024] $layout
  dotest 3
 done
diff --git a/tests/07reshape5intr b/tests/07reshape5intr
index b79d548..3a5f115 100644
--- a/tests/07reshape5intr
+++ b/tests/07reshape5intr
@@ -12,7 +12,7 @@ do
   do dd if=/dev/urandom of=$d bs=1024 || true
   done
 
-  mdadm -CR $md0 -amd -l5 -n$disks --assume-clean $devs
+  mdadm -CR $md0 -amd -l5 -c 256 -n$disks --assume-clean $devs
   mdadm $md0 --add $dev6
   echo 20 > /proc/sys/dev/raid/speed_limit_max
   mdadm --grow $md0 -n $[disks+1]
diff --git a/tests/10ddf-create b/tests/10ddf-create
index a32dc0f..12c3820 100644
--- a/tests/10ddf-create
+++ b/tests/10ddf-create
@@ -12,10 +12,10 @@ mdadm -CR /dev/md/ddf0 -e ddf -n 5 $dev8 $dev9 $dev10 $dev11 $dev12
 mdadm -CR r0 -l0 -n5 /dev/md/ddf0 -z 5000
 mdadm -CR r1 -l1 -n2 /dev/md/ddf0
 mdadm -CR r5 -l5 -n3 /dev/md/ddf0
-testdev /dev/md/r0 5 5000 64
-# r0 will use 4992 due to chunk size, so that leave 27776 for the rest
-testdev /dev/md/r1 1 27776 1
-testdev /dev/md/r5 2 27776 64
+testdev /dev/md/r0 5 5000 512
+# r0 will use 4608 due to chunk size, so that leaves 28160 for the rest
+testdev /dev/md/r1 1 28160 1
+testdev /dev/md/r5 2 28160 512
 dd if=/dev/sda of=/dev/md/r0 || true
 dd if=/dev/sda of=/dev/md/r1 || true
 dd if=/dev/sda of=/dev/md/r5 || true