Wd align - why needed?

WD Internal Drives Desktop & Mobile Drives
1

greetings!

i just bought a 2tb green drive.  why is wd align now needed for these?  didnt need it before.  whats the technical reason??

and after it’s been thru alignment, can it be moved to another machine without the align utility?

i would assume it needs to be re-aligned after deletion of the partition (for whatever reason)

thanks!

2

You don’t need the alignment tool if you’re using Win7, it’s only needed for older OS versions. Win7 will automatically create partitions with proper boundaries. The reason behind this is that if your drive has 4K instead of 512 byte sectors then your partitions on that drive need to be aligned properly (i.e. on 4K boundaries). Some information about drives with 4K sector sizes: http://support.microsoft.com/kb/2510009/en-us

3

i thought sector size was written by the OS when the drive was formated.  only drives more than 2 tb need the larger sector. 

sounds like that’s not the whole story, but thanks for the contribution!

sorry i didnt mention i am on xp 32

ahhh good link thanks

4

Formatting has nothing to do with sector size.  Formatting sets the “Allocation Units”.

On an old hard drive with 512-byte sectors, if you formatted with 4096-byte Allocation Units, then each Allocation Unit of data you write to the disk, occupies 8 physical sectors on the drive.

An Advanced Format drive uses 4096-byte physical sectors to store the data… therefore the Allocation Unit has to be a multiple of 4096 (usually 4096 itself is used).

The “alignment” is basically to do with partitioning… you want partitions to start and end on full sectors, but since older OSes seem to think sectors are ONLY 512 bytes, you can create problems.   The alignment program slightly adjusts the start and end of each partition, to make sure that it starts and ends on a boundary, instead of in the middle of a physical sector.

Once a drive is aligned, you wouldn’t have to re-align it if you moved it to a different computer, but you would have to re-align it if you formatted it or adjusted the size of the partitions.

Drives above 2TB don’t really “need” larger sectors, per se (although it can help with maintaining data integrity as densities increase)… it’s mostly just that it’s more efficient to use larger physical sectors, regardless of drive size, so more and more drives are being produced with 4096-byte physical sectors.  The 2TB issue is a separate matter, as to whether the partition table is MBR or GPT… MBR only has room for 2TB worth of entries… if you try formatting a larger drive with MBR, it will be truncated down to 2TB in size.

5

great!   thanks!

6

RoofingGuy wrote:

Once a drive is aligned, you wouldn’t have to re-align it if you moved it to a different computer, but you would have to re-align it if you formatted it or adjusted the size of the partitions.

 

Unless you formatted it using a Windows 7 computer.