Advanced Format technology makes it possible to build 9.5 mm high 2.5” hard disks with 500 GB per platter. The result is a range of slim and speedy storage giants.

The race to achieve higher and higher hard disk capacities recently entered its next stage. While Western Digital just expanded the GoFlex line with its very first 3.5" 4 TB drive, physically smaller disks are setting records of their own. Now, the very largest 2.5” models (represented by Samsung’s M8 [HN-M101MBB] and Western Digital’s Scorpio Blue [WD10JPVT]) offer 1 TB of storage space.

That’s only half of the innovation, however. After all, 1 TB 2.5“ hard disks have been around since mid-2009. Back then, 1 TB drives used three 333 GB platters, which bumped their height to 12.5 mm (0.5“) and thus prevented them from being installed in most notebooks. Samsung and Western Digital resolved this issue; their 1 TB drives now only sport two 500 GB platters, resulting in a z-height of 9.5 mm (0.374“), which is suitable for laptops.

Advanced Format (AF) Leads to Higher Data Density

The breathtaking speed at which storage density progresses can be partly attributed to the Advanced Format (AF), though up until now it mostly benefited 3.5“ drives. AF sports a sector size of 4 KB, eight times the size of traditional 512-byte sectors. Thus, this format has only one-eighth of the gaps between sectors and one-eighth of the synchronization and error correcting blocks. According to disk manufacturers, AF is responsible for increasing disk capacity by 7 to 11 percent on its own.

In order to maintain compatibility with the outside world, AF-based hard disks emulate 512-byte sectors. Current Windows and Linux systems work flawlessly with AF-based drives; you simply can’t tell the difference. However, older operating systems like Windows XP, Windows Server 2003, and Windows Home Server may exhibit performance problems because they don’t align their partitions to 4 KB boundaries. You can overcome that limitation by downloading an alignment tool from each manufacturer’s website.

Comparison Test of Six 2.5“ Hard Disks with 3 Gb/s SATA Interfaces

Only two of the notebook hard disks we tested offer 1 TB of storage capacity, namely the Samsung M8 HN-M101MBB and Western Digital Scorpio Blue WD10JPVT. The main topic of this test is, however, Advanced Format, as three of the remaining four test candidates are AF-equipped: Hitachi’s Travelstar 5K750 HTS547575A9E384 (750 GB), Samsung’s Spinpoint M8 HN-M500MBB (500 GB), and Western Digital’s Scorpio Black WD7500BPKT (750 GB). In total, five of the six hard disks we’re testing employ AF technology.

The only exception is Toshiba and its MK6461GSYN (640 GB), which does not merely emulate 512-byte sectors, but still uses them internally. The Japanese manufacturer didn’t miss the AF train; it already announced its MQ01ABD100, a 1 TB drive that features 4 KB sectors and a 9.5 mm (0.374“) height.