Disk sector

[1] Newer HDDs and SSDs use 4096 byte (4 KiB) sectors, which are known as the Advanced Format (AF).

[3] Geometrically, the word sector means a portion of a disk between a center, two radii and a corresponding arc (see Figure 1, item B), which is shaped like a slice of a pie.

The address identification is used to ensure that the mechanics of the drive have positioned the read/write head over the correct location.

[7] In the late 1980s ZBR was again used in disk drives then announced by Imprimis and Quantum[8] and by 1997 its industry usage was ubiquitous.

[9] The disk drives and other DASDs announced with the IBM System/360 in 1964 used self-formatting variable length sectors,[disputed (for: the literature does not use the term sector for variable-length blocks)  – discuss] termed records or physical records by IBM.

In 2000 the industry trade organization, International Disk Drive Equipment and Materials Association (IDEMA) started work to define the implementation and standards that would govern sector size formats exceeding 512 bytes to accommodate future increases in data storage capacities.

[11] By the end of 2007 in anticipation of a future IDEMA standard, Samsung and Toshiba began shipments of 1.8-inch hard disk drives with 4096 byte sectors.

While sector specifically means the physical disk area, the term block has been used loosely to refer to a small chunk of data.

[13] For example, the Unix program dd allows one to set the block size to be used during execution with the parameter bs=bytes.

This specifies the size of the chunks of data as delivered by dd, and is unrelated to sectors or filesystem blocks.

However, a larger cluster size reduces bookkeeping overhead and fragmentation, which may improve reading and writing speed overall.

In 1998 the traditional 512-byte sector size was identified as one impediment to increasing capacity which at that time was growing at a rate exceeding Moore's Law.