(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
WD explains how Advanced Formatting works:
[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.
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.
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
, 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.