Future technology for hard disk

Since January 2011, hard disk manufacturers will adopt a new technology called Advanced Format, which will make a big change to future hard disk technology.

As you know, sector is the smallest storage unit in the hard drive. From the beginning about 30 years ago, when the computer also used DOS operating system, the hard drive was formatted into sectors 512 bytes in size.

Figure 1: Traditional sector structure compared to Advanced Format structure.

Each 512-byte sector includes a data location block (Sync / DAM) and an area to store error correction code ECC (Error Correcting Code). In addition, there is a small space between sectors, so the useful capacity of the hard drive is always smaller than the manufacturer's notice.

Dividing into useful 512-byte sectors with a hard drive with a few megabytes (MB) capacity before. But with the development of technology, today's hard drive capacity is up to terabytes (TB) , and today's 512-byte hard drive sector format has shown limitations, wasting capacity. storage.

Raise sector 512 bytes to 4KB

To overcome this problem, the International Disk Drive Equipment and Materials Association ( IDEMA ) and leading hard disk manufacturers have introduced Advanced Format technology (high-end format). ), to increase the capacity of each sector from 512 bytes to 4,096 bytes (4KB).

Currently, files created from software have almost average size larger than 512 bytes. That's why the 512-byte size of a sector becomes ' outdated ' and is also the reason for manufacturers to increase sector size to 4KB.

Each ECC region in a 512-byte sector structure has a size of 40 bytes. Therefore, 512 byte sectors (equivalent to 4KB) will need 320 bytes to store ECC code. Meanwhile, each sector 4KB only needs 100 bytes to store ECC data, saving up to 220 bytes compared to a 512 byte sector structure.

Figure 2: AF logo of Advanced Format technology.

According to Western Digital , one of the pioneers in using Advanced Format, the new format with 4KB sectors will save more hard drive capacity, reduce wasted space about 8 times, performance will also be increased. up 7-11%. At the same time, Advanced Format technology also improves block error correction by up to 50% through the use of larger ECC code.

Since January 2011, hard disk manufacturers around the world are committed to applying this conversion to their new products, and hard drives using Advanced Format technology will all carry the AF logo.

How does AF affect OS?

As mentioned above, AF technology will help increase system performance by up to 7-11%. But that's only for new operating systems later, such as Windows Vista, Windows 7, Mac OS X Tiger, Leopard, Snow Leopard, and Linux versions after September 2009. According to Seagate, the new AF technology hard drive but running the old OS will be slower.

Figure 3: Data is written to the sector according to Advanced Format technology in the wrong location in Windows XP.

Specifically, drives using AF technology are still backward compatible with a 512-byte sector structure by mapping the logical 512-byte sectors to a physical sector. Unfortunately, this approach will have problems on Windows XP . By default, Windows XP creates the primary partition at the 63 block logical address block (LBA), which is the location where a block is missing to divide it by 8. As a result, the data is overwritten to the two boundaries of the block physical 4KB sector. Reading speed and sequential write speed are not much affected, but the speed of random writing or recording small files will be much slow.

However, to support users who want to use the new AF technology hard drive in Windows XP OS, WD has provided WD Align software (download at wdc.com ) to allow new standard drives to work with Maximum performance on Windows XP.