Restore Advanced Format 4k sectors?


I have a number of 2TB WD20EARX (Green) drives which I have previously used in a Windows Home Server (2003). Before I installed 2 of them in that box I used WDAlign to undo the 4k Advanced format sectors and create 512B sectors. That greatly improved performance in that machine. (WHS 2003 is similar to Windows XP in that respect). One of the disks was ‘disk0’ and had the system and a data partition (2 partitions total) so I couldn’t use the 7-8 link on that disk to force a 512B compatibility.

On another drive I simply installed a jumper between pins 7-8 before introducing it to the WHS 2003 where it was used for a single large data partition added to the Drive Extender pool.

Now I am building a Windows 8 machine using Storage Spaces. Before I added the now empty disks to the SS Pool I used PowerShell’s Get-PhysicalDisk|fc to inspect the disk status and notice that even though I have removed the 7-8 links all the disks show 512B sector sizes, which will affect performance in Windows 8.  I wish to restore the original 4k sector size.

So, here’s the question…

How can I undo the WD Align tool’s work of creating 512B sectors and return the disks to the original as-bought 4k sector size of Advanced Format? WD Align appears to only offer the 4k -> 512B direction of realignment and its GUI/wizard does not offer the reverse 512B -> 4k direction. Is there a hidden switch, key sequence, or other incantation to use? Maybe an even more difficult to find WD Unalign application?



The 4096-byte physical sector structure is prerecorded at the factory. There is nothing that any software, including WD Align, can do to change that.

The function of jumper 7-8 is to add a +1 sector offset to each LBA. This means that when Win XP accesses LBA 63, the drive transparently accesses LBA 64 instead. So if the jumper is in place when the drive is partitioned, this means that the first partition will be automatically aligned. If one chooses this jumpering option, then this jumper must remain in place until the next time the drive is partitioned. In contrast to XP, Vista and Windows 7 start the partition at LBA 2048, which is divisible by 8. Therefore the jumper must not be installed for these OSes, otherwise LBA 2048 would be remapped to LBA 2049, thereby misaligning the partition.

I have tried to explain it a little better in the following thread:

As for WD Align, I believe it works by physically moving the data in each sector so that each 4KB cluster falls on a 4KB physical sector boundary. That’s why it takes so long, when the drive is full of data. A better approach, IMHO, would be to remove the 7-8 jumper and repartition the drive using a utility such as GParted which is able to create partitions on 1MiB boundaries (just like Vista and Windows 7). Then you could use WHS 2003 to format these partitions in the usual way.

BTW, AFAIK, the 7-8 alignment jumper may not be functional in all models.