WD Gives You Up To 11% More Space With Advanced Format

WD (Western Digital) is starting to use a new hard disk drive format that enables 7-11% greater capacity on hard disk drives. The disk expansion technique is known as Advanced Format. This technique takes advantage of changes in the industry in drive sector sizes and consolidates overhead information to free up additional space for data storage. As a result of Advanced Format, a 1TB drive could potentially gain more than 100GB in capacity. Other drive manufacturers are also adopting Advanced Format to squeeze more capacity out of existing hard drive technology.

As WD explains, there are three basic methods to increase the capacity on a hard drive: increase the bit density with Advanced Formatting, increase the number of tracks per inch, or increase the number of disk platters. Since boosting bit density takes advantage of space that's already available on every track of a hard disk drive platter, WD chose this route.

WD explains how Advanced Formatting works:
Each [hard disk] track is composed of a series of sectors. Currently the user data on the media is stored in 512 byte sectors. The storage industry is improving this legacy architecture by changing the size of the sectors on the media to store 4,096 bytes of data rather than 512 bytes of data.

Each sector has a gap, Sync/DAM (lead-in) and error correction information. Legacy architecture is very inefficient for ECC (Error Correction Code). It requires lots of overhead to support multiple blocks of ECC.

With Advanced Format technology we can remove Sync/DAM blocks, inter-sector gaps and 8 separate blocks of ECC, and gain approximately 7-11% in disk space.
As an additional benefit, Advanced Format can increase data integrity by providing a more efficient error correction scheme using longer ECC code words. This improves error correction by 50% according to WD.

WD's Caviar Green drives, which are available in capacities up to 2TB, currently use Advanced Format. WD expects to offer additional models and capacities in the future.

Advanced Format is compatible with Windows Vista, Windows 7, and Mac OS X; it's not optimized for Windows XP or older operating systems. For users with older operating systems, WD's Align software utility can be used to align partitions on the Advanced Format drive to ensure it provides full performance for certain configurations.