Preparing Advanced Format hard drives for Microsoft Windows installations on HP Business Notebook PCs, Workstations, and Desktop PCs

Appendix A: Technical background

Since standards were introduced in 1956, industry-standard HDDs have used 512-byte sectors on

their internal media. However, this relatively small sector size constrains storage capacity and has

also caused manufacturing capabilities to reach a limit.

Under the sponsorship and support of the International Disk Drive Equipment and Materials

Association (IDEMA), manufacturers of industry-standard HDDs are transitioning from 512-byte to 4-

KB sectors on HDDs with SATA interfaces, increasing the utilization of storage space and making the

newer disks easier to manufacture. HDDs with SAS interfaces are expected to transition later, possibly

not before 2013.

HDD manufacturers began shipping these Advanced Format drives (4-KB sectors) in the fourth quarter

of 2010 as newly-announced models. Previously-announced and currently-shipping models are not

expected to transition to media with 4-KB sectors.

By using standard 512-byte sector SATA communications, first-generation Advanced Format drives

maintain backwards-compatibility with current computers. Thus, these drives – sometimes referred to

as 512e drives or translated drives – operate internally at 4 KB and externally at 512 bytes.

However, this disparity in sector sizes can lead to performance issues.

Partition alignment

Modern operating systems use file systems with 4-KB sectors when formatting a partition. However,

when the physical media and file system both use 4-KB sectors, while the SATA interface is 512-byte,

misalignment can occur, impacting write performance.

Note

Misalignment occurs while file system sectors cross physical sector

boundaries.

To address the risk of misalignment, a 512e drive emulates the logical 512-byte interface, taking care

of all physical manipulation in the background, while maintaining backwards compatibility. However,

emulation can affect performance with older operating systems such as Windows XP. This can be

fixed by either reinstalling the operating system with newer install tools that are 4-KB sector-aware or

using a utility that properly aligns the partitions and data on the drive.