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Advanced Format

Advanced Format (AF) is the standard that improves formatting efficiency by increasing the length of HDD data sectors to be longer than their traditional size of 512 bytes. The Advanced Format standard was formulated by the International Disk Drive Equipment and Materials Association (IDEMA) in which Toshiba Electronic Devices & Storage Corporation and other HDD manufacturers participate. By establishing the Advanced Format standard, IDEMA aims to ensure that the storage devices supplied by various companies will be compatible with file systems and operating systems (OS) generations that support AF sector technology.

Advanced Format improves formatting efficiency and the reliability of recorded data by increasing the length of data sectors and relative strength of the error detection and correction algorithms. The generation one Advanced Format standards stipulate a physical sector size of 4,096 bytes and includes the ability to logically emulate the older 512-byte sectors (sometimes called "512e")in order to maintain compatibility with applications or hardware which demand conventional 512-byte sector technology. During emulation, when the host sends the disk drive data to be stored in increments of 512 bytes, the disk drive places the emulated 512-byte sector at an appropriate position within a larger physical 4,096 bytes sector and then writes the 4,096 bytes sector to the disk media.

Some file systems and operating systems generations have advanced to support the physical 4096-byte sector as the logical sector size. Such host systems are called "4K native (4Kn)" capable. Since both the physical and logical sector length are 4096 bytes, emulation of the older 512-byte sectors is no longer required, allowing the 4Kn host to use the available 4Kn disk storage more efficiently. We have made available HDDs of the 512-byte emulation type, the 4Kn type, and the 512 native type, to provide the sector technology that will fit the host systems’ specification.

Examples of Advanced Format Icons recommended by IDEMA

The symbols below are not necessarily printed on the products with the described features.

512-byte emulation (512e)
The "Advanced Format AF" and "AF" symbols generally mean the disk supports 512-byte emulation; but it may also be used on disks capable of both 512e and 4Kn operation.
4K native (4Kn)
The "Advanced Format 4Kn" and "4Kn" symbols mean the disk drive support 4K byte sector length only.

Toshiba Alignment Tool for Advanced Format Hard Disk Drives (HDD) no longer be available for download

TOSHIBA CORPORATION and its affiliated companies (“Toshiba”) made available a Partition Alignment Tool for customers that use Toshiba 4K Advanced Format (AF) hard disk drives (HDD) in Microsoft® Windows® XP operating system (OS) environments. With Microsoft® ending complete support for its Windows® XP OS on April 8 2014, Toshiba will no longer offer the Partition Alignment Tool.

Customers planning to continue use of Windows® XP along with Toshiba AF HDDs should consider the use of a third party alignment tool as it may help improve overall system performance.

An unaffiliated, 3rd party vendor that provides an alignment tool for use with 4K AF HDDs is, for example, Paragon Software It is important to note that Toshiba does not recommend or endorse Paragon Software or any other 3rd party vendor or 4K alignment utility. The use of such software is entirely at the user’s own discretion and risk, and Toshiba is in no way responsible for such use.

  • Microsoft, Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries.


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