429:
711:. Increasing the length of the data field through the implementation of Advanced Format using 4096-byte sectors removed this impediment; it increased the efficiency of the data surface area by five to thirteen percent while increasing the strength of the ECC which in turn allowed higher capacity. The format was standardized by an industry consortium in 2005 and by 2011 incorporated in all new products of all hard drive manufacturers.
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264:(CRC) replacing parity per character detection of prior generations. These IBM physical records have three basic parts, a Count field which acts as an ID field, an optional Key field to aid in searching for data and a Data field; in practice, most records had no Key field, indicated by a key length of zero. The structure of these three fields is called the
313:) 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. 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. In 2010 IDEMA completed the
620:. For cluster sizes which are small versus the average file size, the wasted space per file will be statistically about half of the cluster size; for large cluster sizes, the wasted space will become greater. However, a larger cluster size reduces bookkeeping overhead and fragmentation, which may improve
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If a sector is defined as the intersection between a radius and a track, as was the case with early hard drives and most floppy disks, the sectors towards the outside of the disk are physically longer than those nearer the spindle. Because each sector still contains the same number of bytes, the
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than the inner ones, which is an inefficient use of the magnetic surface. The solution is zone bit recording, wherein the disk is divided into zones, each encompassing a small number of contiguous tracks. Each zone is then divided into sectors such that each sector has a similar physical size.
144:
The sector is the minimum storage unit of a hard drive. Most disk partitioning schemes are designed to have files occupy an integral number of sectors regardless of the file's actual size. Files that do not fill a whole sector will have the remainder of their last sector filled with zeroes. In
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A consequence of zone bit recording is that contiguous reads and writes are noticeably faster on outer tracks (corresponding to lower block addresses) than on inner tracks, as more bits pass under the head with each rotation; this difference can be 25% or more.
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Prior to the 1980s, there was little standardization of sector sizes; disk drives had a maximum number of bits per track and various system manufacturers subdivided the track into different sector sizes to suit their OSes and applications. The popularity of the
211:, had ten 100 character sectors per track; each character was six bits and included a parity bit. The number of sectors per track was identical on all recording surfaces. There was no recorded identifier field (ID) associated with each sector.
601:) is a unit of disk space allocation for files and directories. To reduce the overhead of managing on-disk data structures, the filesystem does not allocate individual disk sectors by default, but contiguous groups of sectors, called clusters.
233:(ZBR) which allowed the number of sectors per track to vary as a function of the track's diameter – there are more sectors on an outer track than on an inner track. In the late 1980s ZBR was again used in disk drives then announced by
275:
replaced the CRC on the data field of each record with an error correcting code (ECC) to improve data integrity by detecting most errors and allowing correction of many errors. Ultimately all fields of disk sectors had ECCs.
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A cluster is the smallest logical amount of disk space that can be allocated to hold a file. Storing small files on a filesystem with large clusters will therefore waste disk space; such wasted disk space is called
226:
by IBM, and added to each record a record address field separate from the data in a record. All modern disk drives have sector address fields, called ID fields, separate from the data in a sector.
317:
standard for 4096 sector drives, setting the date for the transition from 512 to 4096 byte sectors as
January 2011 for all manufacturers, and Advanced Format drives soon became prevalent.
338:
is an abstraction over disk sectors possibly encompassing multiple sectors. In other contexts, it may be a unit of a data stream or a unit of operation for a utility. For example, the
195:
is used to ensure that the mechanics of the drive have positioned the read/write head over the correct location. The data area contains the sync bytes, user data and an
245:
187:
area (typically called "ID") and the data area. The sector header contains information used by the drive and controller; this information includes sync bytes,
191:, flaw flag and error detection and correction information. The header may also include an alternate address to be used if the data area is undependable. The
707:
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
334:
has been used loosely to refer to a small chunk of data. Block has multiple meanings depending on the context. In the context of data storage, a
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302:
DASD. CKD DASD supported multiple variable length sectors while the IBM FBA DASD supported sector sizes of 512, 1024, 2048, or 4096 bytes.
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IBM 1301, Models 1 and 2, Disk
Storage and IBM 1302, Models 1 and 2, Disk Storage with IBM 7090, 7094, and 7094 II Data Processing Systems
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IBM 1301, Models 1 and 2, Disk
Storage and IBM 1302, Models 1 and 2, Disk Storage with IBM 1410 and 7010 Data Processing Systems
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in the late 1980s led to a 512-byte sector becoming an industry standard sector size for HDDs and similar storage devices.
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352:. This specifies the size of the chunks of data as delivered by dd, and is unrelated to sectors or filesystem blocks.
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Because outer zones have a greater circumference than inner zones, they are allocated more sectors. This is known as
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and writing speed overall. Typical cluster sizes range from 1 sector (512 B) to 128 sectors (64
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This article is about sectors on magnetic disk drives. For sectors on magnetic drum drives, see
113:. For most disks, each sector stores a fixed amount of user-accessible data, traditionally 512
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On a disk that uses 512-byte sectors, a 512-byte cluster contains one sector, whereas a 4-
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Please help update this article to reflect recent events or newly available information.
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In modern disk drives, each physical sector is made up of two basic parts, the sector
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is used, may even be discontiguous within a track. This should not be confused with
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A "lost cluster" occurs when a file is deleted from the directory listing, but the
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A cluster need not be physically contiguous on the disk; it may span more than one
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allows one to set the block size to be used during execution with the parameter
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305 RAMAC Random Access Method of
Accounting and Control Manual of Operation
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Porter, James (October 1988). "Rigid
Magnetic Disk Drive Specifications".
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168:(see Figure 1, item B), which is shaped like a slice of a pie. Thus, the
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Porter, James (June 1997). "Rigid
Magnetic Disk Drive Specifications".
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by IBM. They detected errors in all fields of their records with a
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Also in 1961 Bryant with its 4000 series introduced the concept of
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While sector specifically means the physical disk area, the term
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in 1964 used self-formatting variable length sectors, termed
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International Disk Drive
Equipment and Materials Association
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371:"Data cluster" redirects here. Not to be confused with
1096:"Errors Caused by Cross-Linked Files or Lost Clusters"
650:(FAT) still shows the clusters allocated to the file.
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4.0. However the term cluster is still widely used.
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of parts of this article (those related to article)
495:. Unsourced material may be challenged and removed.
172:(Figure 1, item C) refers to the intersection of a
355:In Linux, disk sector size can be determined with
968:Reference Manual for IBM 3330 Series Disk Storage
643:, as the sectors are still logically contiguous.
444:may be compromised due to out-of-date information
145:practice, operating systems typically operate on
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241:and by 1997 its industry usage was ubiquitous.
284:beginning in the 1980s and the advent of the
29:Logical or physical division of storage media
978:
133:. Newer HDDs and SSDs use 4096 byte (4
1072:"Disk Sector and Block Allocation For File"
416:Learn how and when to remove these messages
218:introduced variable length sectors, termed
366:
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953:1997 DISK/TREND REPORT, RIGID DISK DRIVES
938:1988 DISK/TREND REPORT, RIGID DISK DRIVES
832:Computer Science Handbook, Second Edition
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573:Learn how and when to remove this message
555:Learn how and when to remove this message
305:In 2000 the industry trade organization,
1150:, National Semiconductor, archived from
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359:and block size can be determined with
1028:from the original on 14 December 2020
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493:adding citations to reliable sources
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940:. DISK/TREND, Inc. p. 63, 122.
248:and other DASDs announced with the
149:, which may span multiple sectors.
24:
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612:) cluster contains eight sectors.
357:sudo fdisk -l | grep "Sector size"
137:) sectors, which are known as the
34:Track (moving medium) § Drums
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1011:Skinner, Heather (29 June 2010).
925:. Bryant Computer Products. 1963.
397:This section has multiple issues.
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991:"The Advent of Advanced Format"
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802:Hamington, Suzie (2004-01-01).
480:needs additional citations for
405:or discuss these issues on the
361:sudo blockdev --getbsz /dev/sda
207:The first disk drive, the 1957
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298:(FBA DASDs) to its line of
121:(HDDs), and 2048 bytes for
43:Figure 1: Disk structures:
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835:. CRC Press. p. 86.
680:outer sectors have lower
367:Sectors versus clusters
293:fixed-block architecture
291:In the 1970s, IBM added
152:Geometrically, the word
1119:Mueller, Scott (2002).
593:(sometimes also called
262:cyclic redundancy check
1052:unix.stackexchange.com
193:address identification
189:address identification
160:between a center, two
101:is a subdivision of a
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648:File Allocation Table
373:clustered file system
326:Sectors versus blocks
273:IBM 3330 disk storage
216:IBM 1301 disk storage
197:error-correcting code
156:means a portion of a
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1186:Units of information
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489:improve this article
209:IBM 350 disk storage
164:and a corresponding
687:zoned bit recording
637:sector interleaving
955:. DISK/TREND, Inc.
779:"UDF - OSDev Wiki"
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585:In computer
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482:verification
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93:In computer
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18:Data cluster
1123:, p. 1354.
1032:14 December
709:Moore's Law
682:bit density
618:slack space
246:disk drives
170:disk sector
1175:Categories
1161:2010-03-10
1106:2020-08-03
1081:2015-12-13
1057:2015-12-13
997:2013-11-18
788:2024-09-01
765:References
515:newspapers
402:improve it
653:The term
545:June 2011
408:talk page
271:The 1970
214:The 1961
1026:Archived
715:See also
606:kibibyte
350:bs=bytes
235:Imprimis
127:DVD-ROMs
993:. IDEMA
868:. 1957.
655:cluster
635:or, if
622:reading
591:cluster
529:scholar
343:program
254:records
239:Quantum
220:records
203:History
131:BD-ROMs
123:CD-ROMs
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536:JSTOR
522:books
332:block
311:IDEMA
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162:radii
115:bytes
105:on a
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237:and
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129:and
117:for
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375:or
300:CKD
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