X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=align%2Fvirt-alignment-scan.pod;h=5eb9312d368602b5ebfd071c33ee9f626a2a2d8f;hb=22c72b911e65b93cfd049f42e6bd1b9ad7d55299;hp=dcc71b4a223bb20d2685c1f9a4c952dd1e3eb1fe;hpb=df711241fff32036acbc3fae10486816cbdd8ef9;p=libguestfs.git

diff --git a/align/virt-alignment-scan.pod b/align/virt-alignment-scan.pod
index dcc71b4..5eb9312 100755
--- a/align/virt-alignment-scan.pod
+++ b/align/virt-alignment-scan.pod
@@ -229,8 +229,10 @@ data combined, and the two blocks written back (4x I/O).
 New versions of the Linux kernel expose the physical and logical block
 size, and minimum and recommended I/O size.
 
-For a typical hard drive with 512 byte sectors:
+For a typical consumer hard drive with 512 byte sectors:
 
+ $ cat /sys/block/sda/queue/hw_sector_size
+ 512
  $ cat /sys/block/sda/queue/physical_block_size
  512
  $ cat /sys/block/sda/queue/logical_block_size
@@ -240,6 +242,19 @@ For a typical hard drive with 512 byte sectors:
  $ cat /sys/block/sda/queue/optimal_io_size
  0
 
+For a new consumer hard drive with 4Kbyte sectors:
+
+ $ cat /sys/block/sda/queue/hw_sector_size
+ 4096
+ $ cat /sys/block/sda/queue/physical_block_size
+ 4096
+ $ cat /sys/block/sda/queue/logical_block_size
+ 4096
+ $ cat /sys/block/sda/queue/minimum_io_size
+ 4096
+ $ cat /sys/block/sda/queue/optimal_io_size
+ 0
+
 For a NetApp LUN:
 
  $ cat /sys/block/sdc/queue/logical_block_size
@@ -258,8 +273,8 @@ is 64K.
 For detailed information about what these numbers mean, see
 L<http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newstorage-iolimits.html>
 
-[Thanks to Mike Snitzer for providing NetApp data and additional
-information.]
+[Thanks to Matt Booth for providing 4K drive data.  Thanks to Mike
+Snitzer for providing NetApp data and additional information.]
 
 =head2 1 MB PARTITION ALIGNMENT
 
@@ -275,24 +290,15 @@ will start at a multiple of 2048 sectors.
 
 =head2 SETTING ALIGNMENT
 
-Currently there is no virt tool for fixing alignment problems in
-guests.  This is a difficult problem to fix because simply moving
-partitions around breaks the bootloader, necessitating either manual
-reinstallation of the bootloader using a rescue disk, or complex and
-error-prone hacks.
-
-L<virt-resize(1)> does not change the alignment of the first
-partition, but it does align the second and subsequent partitions to a
-multiple of 64 or 128 sectors (depending on the version of
-virt-resize, 128 in virt-resize E<ge> 1.13.19).  For operating systems
-that have a separate boot partition, virt-resize could be used to
-align the main OS partition, so that the majority of OS accesses
-except at boot will be aligned.
-
-The easiest way to correct partition alignment problems is to
-reinstall your guest operating systems.  If you install operating
-systems from templates, ensure these have correct partition alignment
-too.
+L<virt-resize(1)> can change the alignment of the partitions of some
+guests.  Currently it can fully align all the partitions of all
+Windows guests, and it will fix the bootloader where necessary.  For
+Linux guests, it can align the second and subsequent partitions, so
+the majority of OS accesses except at boot will be aligned.
+
+Another way to correct partition alignment problems is to reinstall
+your guest operating systems.  If you install operating systems from
+templates, ensure these have correct partition alignment too.
 
 For older versions of Windows, the following NetApp document contains
 useful information: L<http://media.netapp.com/documents/tr-3747.pdf>
@@ -372,4 +378,4 @@ GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
-Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.