Editing Hard disk drive (section)

== History ==
{{Main|History of hard disk drives}}
{{Infobox computer hardware
| image = IBM 350 RAMAC.jpg
| caption     = A partially disassembled IBM 350 hard disk drive (RAMAC)
| invent-date = {{Start date and age|1954|12|24}}{{Efn|This is the original filing date of the application which led to US Patent 3,503,060, generally accepted as the definitive hard disk drive patent.<ref>Kean, David W., 1977, ''IBM San Jose: A quarter century of innovation''. San Jose, CA: International Business Machines Corporation. CHM accession number: 102687875.</ref>}}
| invent-name = [[IBM]] team led by [[Rey Johnson]] 
}}

{| class="wikitable floatright" style="max-width: 35em;"
|+ Improvement of HDD characteristics over time
|-
! Parameter !! Started&nbsp;with&nbsp;(1957) !! Improved&nbsp;to!! Improvement
|-
| Capacity<br />(formatted) || 3.75&nbsp;[[megabyte]]s<ref name="350Cap" /> 
|| 36&nbsp;[[terabyte]]s ({{as of|2025|lc=on}})<ref>{{Cite web |last=Athow |first=Desire |date=2025-01-21 |title=Seagate smashes largest HDD world record with 36TB hard drive and reveals a 60TB model is coming |url=https://www.techradar.com/pro/seagate-smashes-largest-hdd-world-record-with-36tb-hard-drive-and-reveals-a-60tb-model-is-coming |access-date=2025-03-18 |website=TechRadar |language=en}}</ref><ref name="x-mozaic"/><ref>[https://investors.seagate.com/news/news-details/2024/Seagates-Breakthrough-30TB-Hard-Drives-Ramp-Volume-Marking-an-Inflection-Point-in-the-Storage-Industry/default.aspx Seagate’s Breakthrough 30TB+ Hard Drives Ramp Volume, Marking an Inflection Point in the Storage Industry]</ref>
|| 9.6-million-to-one{{efn|36,000,000,000,000 ÷ 3,750,000}}
|-
| Physical volume || {{convert|68|cuft|lk=on}}{{Efn|Comparable in size to two large refrigerators.}}<ref name="IBM350" /> || {{convert|2.1|cuin|cm3|lk=on}}<ref name="AutoMK-59">{{cite press release | title = Toshiba Storage Solutions&nbsp;– MK3233GSG | url = https://www.toshiba.co.jp/about/press/2009_11/pr0501.htm | access-date = November 7, 2009 | archive-url = https://web.archive.org/web/20120724122541/http://www.toshiba.co.jp/about/press/2009_11/pr0501.htm | archive-date = July 24, 2012 | url-status = live }}</ref>{{Efn| The 1.8-inch form factor is obsolete; sizes smaller than 2.5 inches have been replaced by flash memory.}} || 56,000-to-one{{efn|68 × 12 × 12 × 12 ÷ 2.1}}
|-
| Weight || {{convert|2000|lb|kg|lk=on|disp=br()|abbr=out}}<ref name="IBM350" /> || {{convert|2.2|oz|g|lk=on|disp=br()|abbr=out}}<ref name="AutoMK-59"/> || 15,000-to-one{{efn|910,000 ÷ 62}}
|-
| Average [[access time]] || approx. 600&nbsp;[[millisecond]]s<ref name="IBM350" /> || 2.5&nbsp;ms to 10&nbsp;ms; RW RAM dependent || about<br />200-to-one{{efn|600 ÷ 2.5}}
|-
| Price || {{US$|9,200}} per megabyte (1961;<ref>Ballistic Research Laboratories "A THIRD SURVEY OF DOMESTIC ELECTRONIC DIGITAL COMPUTING SYSTEMS," March 1961, [http://www.ed-thelen.org/comp-hist/BRL61-ibm03.html#IBM-305-RAMAC section on IBM 305 RAMAC] {{Webarchive|url=https://web.archive.org/web/20150302120119/http://ed-thelen.org/comp-hist/BRL61-ibm03.html#IBM-305-RAMAC |date=March 2, 2015 }} (p. 314-331) states a $34,500 purchase price which calculates to $9,200/MB.</ref> {{US$|97,500}} in 2022)
|| US$14.4 per [[terabyte]] by end of 2022<ref>{{cite web
 |url=https://www.backblaze.com/blog/hard-drive-cost-per-gigabyte/
 |title=Hard Drive Cost Per Gigabyte |last=Klein |first=Andy |date=November 29, 2022
 |publisher=Backblaze |access-date=November 22, 2023}}</ref>
|| 6.8-billion-to-one{{efn|(97,500 ÷ 14.4] *  10^6.}}<!-- seemingly outdated -->
|-
| [[Data density]] || 2,000&nbsp;[[bit]]s per [[square inch]]<ref>{{cite web
 | url =https://www-03.ibm.com/ibm/history/exhibits/storage/storage_magnetic.html
 | title =Magnetic head development
 | website =IBM Archives
 | access-date =August 11, 2014
 | archive-url =https://web.archive.org/web/20150321114231/http://www-03.ibm.com/ibm/history/exhibits/storage/storage_magnetic.html
 | archive-date =March 21, 2015
 | url-status =dead
 }}</ref> || 1.4 [[terabit]]s per square inch in 2023<ref name="WDHC680">{{cite web
 |url=https://www.westerndigital.com/tools/documentRequestHandler?docPath=/content/dam/doc-library/en_us/assets/public/western-digital/product/data-center-drives/ultrastar-dc-hc600-series/data-sheet-ultrastar-dc-hc680.pdf
 |title=Ultrastar DC HC690 Data Sheet |date=October 2023 |publisher=Western Digital
 |access-date=November 22, 2023}}</ref> || 700-million-to-one{{efn|1,400,000,000,000 ÷ 2,000.}}
|-
| Average lifespan || c. 2000 hrs [[MTBF]]{{citation needed|date=November 2016}} || c. 2,500,000 hrs (~285 years) MTBF<ref>{{cite web |url=https://www.hgst.com/products/hard-drives/ultrastar-he12 |title=Ultrastar DC HC500 Series HDD |work=Hgst.com |access-date=February 20, 2019 |archive-url=https://web.archive.org/web/20180829180648/http://www.hgst.com/products/hard-drives/ultrastar-he12 |archive-date=August 29, 2018 |url-status=live }}</ref> || 1250-to-one{{efn|2,500,000 ÷ 2,000.}}
|}

=== 1950s–1960s ===
The first production IBM hard disk drive, the [[IBM 350|350 disk storage]], shipped in 1957 as a component of the IBM 305 RAMAC system. It was approximately the size of two large refrigerators and stored five million six-bit characters (3.75 [[megabyte]]s)<ref name="350Cap">{{cite web
|title=Comment: Time Capsule, 1956 Hard Disk
|url=http://www.oracle.com/technetwork/issue-archive/2014/14-jul/o44timecapsule-2219543.html
|quote=IBM 350 disk drive held 3.75&nbsp;MB
|series=Oracle Magazine
|date=July 2014
|access-date=September 19, 2014
|archive-url=https://web.archive.org/web/20140811202917/http://www.oracle.com/technetwork/issue-archive/2014/14-jul/o44timecapsule-2219543.html
|archive-date=August 11, 2014
|url-status=live
}}</ref> on a stack of 52 disks (100 surfaces used).<ref name="ibm-350-dsu">{{cite web|title=IBM Archives: IBM&nbsp;350 disk storage unit|url=https://www-03.ibm.com/ibm/history/exhibits/storage/storage_350.html|publisher=IBM|access-date=July 26, 2015|date=January 23, 2003|archive-url=https://web.archive.org/web/20150617040819/https://www-03.ibm.com/ibm/history/exhibits/storage/storage_350.html|archive-date=June 17, 2015|url-status=dead}}</ref> The 350 had a single arm with two read/write heads, one facing up and the other down, that moved both horizontally between a pair of adjacent platters and vertically from one pair of platters to a second set.<ref name=ibm-650>{{citation
 |   title = IBM 650 RAMAC Manual of Operations
 |      id = 22-6270-3
 | edition = 4th
 |    date = June 1, 1957
 |   quote = Three mechanically independent access arms are provided for each file unit, and each arm can be independently directed to any track in the file.
 | chapter = 355 DISK STORAGE
 |    page = 17
 }}
</ref><ref name=ibm-7070>{{citation
 |   title = IBM Reference Manual 7070 Data Processing System
 |      id = A22-7003-1
 | edition = 2nd
 |    date = January 1960
 |   quote = Each disk-storage unit has three mechanically independent access arms, all of which can be seeking at the same time. 
 | chapter = Disk Storage
 |     chapter-url = https://bitsavers.org/pdf/ibm/7070/A22-7003-01_7070_Reference_Jan60.pdf
 }}
</ref><ref name=ibm-1401>{{citation
 |   title = Reference Manual IBM 1401 Data Processing System
 |      id = A24-1403-5
 |    date = April 1962
 | edition = 6th
 |   quote = The disk storage unit can have two access arms. One is standard and the other is available as a special feature.
 | chapter = IBM RAMAC 1401 System
 |    page = 63
 |     chapter-url = https://bitsavers.org/pdf/ibm/1401/A24-1403-5_1401_Reference_Apr62.pdf
 }}
</ref>  Variants of the IBM 350 were the [[IBM 355]], [[IBM 7300]] and [[IBM 1405]].

In 1961, IBM announced, and in 1962 shipped, the IBM&nbsp;1301 disk storage unit,<ref>{{cite web|url=https://www-03.ibm.com/ibm/history/exhibits/storage/storage_1301.html|title=IBM Archives: IBM 1301 disk storage unit|work=ibm.com|date=January 23, 2003|access-date=June 25, 2015|archive-url=https://web.archive.org/web/20141219183129/http://www-03.ibm.com/ibm/history/exhibits/storage/storage_1301.html|archive-date=December 19, 2014|url-status=dead}}</ref> which superseded
the IBM&nbsp;350 and similar drives. The 1301 consisted of one (for Model 1) or two (for model 2) modules, each containing 25 platters, each platter about {{convert|1/8|inch|mm|adj=on}} thick and {{convert|24|inch|mm}} in diameter.<ref>{{cite web|url=http://www.computermuseum.li/Testpage/DiskPlatter-1301.htm|title=DiskPlatter-1301|work=computermuseum.li|url-status=dead|archive-url=https://web.archive.org/web/20150328161124/http://www.computermuseum.li/Testpage/DiskPlatter-1301.htm|archive-date=March 28, 2015}}</ref> While the earlier IBM disk drives used only two read/write heads per arm, the 1301 used an array of 48{{efn|40 for user data, one for format tracks, 6 for alternate surfaces and one for maintenance.}} heads (comb), each array moving horizontally as a single unit, one head per surface used. [[Cylinder-head-sector|Cylinder-mode]] read/write operations were supported, and the heads flew about 250 micro-inches (about 6&nbsp;μm) above the platter surface. Motion of the head array depended upon a binary adder system of hydraulic actuators which assured repeatable positioning. The 1301 cabinet was about the size of three large refrigerators placed side by side, storing the equivalent of about 21 million eight-bit bytes per module. Access time was about a quarter of a second.

Also in 1962, IBM introduced the [[IBM 1311|model 1311]] disk drive, which was about the size of a washing machine and stored two million characters on a removable [[disk pack]]. Users could buy additional packs and interchange them as needed, much like reels of [[magnetic tape]]. Later models of removable pack drives, from IBM and others, became the norm in most computer installations and reached capacities of 300 megabytes by the early 1980s. Non-removable HDDs were called "fixed disk" drives.

In 1963, IBM introduced the 1302,<ref name="1301Ref">{{cite book
 |     title = 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
 |        id = A22-6785
 |       url = https://bitsavers.org/pdf/ibm/7090/A22-6785_1301_1302_on_709x.pdf
 | publisher = IBM
 }}
</ref> with twice the track capacity and twice as many tracks per cylinder as the 1301. The 1302 had one (for Model 1) or two (for Model 2) modules, each containing a separate comb for the first 250 tracks and the last 250 tracks.

{{Anchor|fixed-head}}Some high-performance HDDs were manufactured with one head per track, ''e.g.'', Burroughs B-475 in 1964, [[History of IBM magnetic disk drives#IBM 2305|IBM&nbsp;2305]] in 1970, so that no time was lost physically moving the heads to a track and the only latency was the time for the desired block of data to rotate into position under the head.<ref>Microsoft Windows NT Workstation 4.0 Resource Guide 1995, Chapter 17 – Disk and File System Basics</ref> Known as fixed-head or head-per-track disk drives, they were very expensive and are no longer in production.<ref name="CHAUDHURI2008">{{Cite book |last=Chaudhuri |first=P. Pal |title=Computer Organization and Design |url=https://books.google.com/books?id=5LNwVRpfkRgC&q=%22fixed+head%22&pg=PA568 |date=April 15, 2008 |publisher=PHI Learning Pvt. Ltd. |isbn=978-81-203-3511-0 |page=568|edition=3rd }}</ref>

=== 1970s ===
In 1973, IBM introduced a new type of HDD code-named "[[IBM 3340|Winchester]]". Its primary distinguishing feature was that the disk heads were not withdrawn completely from the stack of disk platters when the drive was powered down. Instead, the heads were allowed to "land" on a special area of the disk surface upon spin-down, "taking off" again when the disk was later powered on. This greatly reduced the cost of the head actuator mechanism but precluded removing just the disks from the drive as was done with the disk packs of the day. Instead, the first models of "Winchester technology" drives featured a removable disk module, which included both the disk pack and the head assembly, leaving the actuator motor in the drive upon removal. Later "Winchester" drives abandoned the removable media concept and returned to non-removable platters.

In 1974, IBM introduced the swinging arm actuator, made feasible because the Winchester recording heads function well when skewed to the recorded tracks. The simple design of the IBM GV (Gulliver) drive,<ref>"Design of a Swinging Arm Actuator for a disk file" J. S. HEATH IBM J. RES. DEVELOP. July 1976</ref> invented at IBM's UK Hursley Labs, became IBM's most licensed electro-mechanical invention<ref>US 3,849,800 Magnetic disk apparatus. Cuzner, Dodman, Heath, & Rigbey</ref> of all time, the actuator and filtration system being adopted in the 1980s eventually for all HDDs, and still universal nearly 40 years and 10 billion arms later.

Like the first removable pack drive, the first "Winchester" drives used platters {{convert|14|in}} in diameter. In 1978, IBM introduced a swing arm drive, the IBM 0680 (Piccolo), with eight-inch platters, exploring the possibility that smaller platters might offer advantages. Other eight-inch drives followed, then {{convert|5+1/4|in|abbr=on}} drives, sized to replace the contemporary [[floppy disk drive]]s. The latter were primarily intended for the then fledgling personal computer (PC) market.

=== 1980s–1990s ===
Over time, as recording densities were greatly increased, further reductions in disk diameter to 3.5" and 2.5" were found to be optimum. Powerful rare-earth magnet materials became affordable during this period and were complementary to the swing arm actuator design to make possible the compact form factors of modern HDDs.

As the 1980s began, HDDs were a rare and very expensive additional feature in PCs, but by the late 1980s, their cost had been reduced to the point where they were standard on all but the cheapest computers.

Most HDDs in the early 1980s were sold to PC end users as an external, add-on subsystem. The subsystem was not sold under the drive manufacturer's name but under the subsystem manufacturer's name such as [[Corvus Systems]] and [[Tallgrass Technologies]], or under the PC system manufacturer's name such as the [[Apple ProFile]]. The [[IBM PC/XT]] in 1983 included an internal 10&nbsp;MB HDD, and soon thereafter, internal HDDs proliferated on personal computers.

External HDDs remained popular for much longer on the [[Apple Macintosh]]. Many Macintosh computers made between 1986 and 1998 featured a [[SCSI]] port on the back, making external expansion simple. Older compact Macintosh computers did not have user-accessible hard drive bays (indeed, the [[Macintosh 128K]], [[Macintosh 512K]], and [[Macintosh Plus]] did not feature a hard drive bay at all), so on those models, external SCSI disks were the only reasonable option for expanding upon any internal storage.

=== 21st century ===
HDD improvements have been driven by increasing [[Density (computer storage)|areal density]], listed in the table above. Applications expanded through the 2000s, from the [[mainframe computer]]s of the late 1950s to most [[mass storage]] applications including computers and consumer applications such as storage of entertainment content.

In the 2000s and 2010s, NAND began supplanting HDDs in applications requiring portability or high performance. NAND performance is improving faster than HDDs, and applications for HDDs are eroding. In 2018, the largest hard drive had a capacity of 15&nbsp;TB, while the largest capacity SSD had a capacity of 100&nbsp;TB.<ref name= "100TB 2018"/> In 2018, HDDs were forecast to reach 100&nbsp;TB capacities around 2025 (but so far in 2025 the reality is far off),<ref>{{cite web|last=Mott |first=Nathaniel |url=http://tomshardware.com/news/seagate-hamr-100tb-drives-2025,38035.html |title=Seagate Wants to Ship 100TB HDDs by 2025 |work=Tomshardware.com |date=November 7, 2018 |access-date=February 20, 2019}}</ref> but {{as of|2019|lc=on}}, the expected pace of improvement was pared back to 50&nbsp;TB by 2026.<ref name= "blocks WWrevenue August2019" >{{cite web |url= https://blocksandfiles.com/2019/09/23/seagate-assumes-ssds-wont-kill-disk-drives/ |title= How long before SSDs replace nearline disk drives? |last= Mellor |first= Chris |date= September 23, 2019 |quote= the total addressable market for disk drives will grow from $21.8bn in 2019 |access-date= November 15, 2019 }}</ref> Smaller form factors, 1.8-inches and below, were discontinued around 2010. The cost of solid-state storage (NAND), represented by [[Moore's law]], is improving faster than HDDs. NAND has a higher [[price elasticity of demand]] than HDDs, and this drives market growth.<ref name= Appleton >{{cite web |url= https://www.cnet.com/news/flash-goes-the-notebook/ |title= Flash goes the notebook |last= Kanellos |first= Michael |date= January 17, 2006 |website= CNET |access-date= May 15, 2018 |archive-url= https://web.archive.org/web/20180519203122/https://www.cnet.com/news/flash-goes-the-notebook/ |archive-date= May 19, 2018 |url-status= live }}</ref> During the late 2000s and 2010s, the [[Marketing#Product life cycle|product life cycle]] of HDDs entered a mature phase, and slowing sales may indicate the onset of the declining phase.<ref name= lifecycle >{{cite web |url= https://www.inc.com/encyclopedia/industry-life-cycle.html |title= Industry Life Cycle - Encyclopedia - Business Terms |work= Inc. |access-date= May 15, 2018 |archive-url= https://web.archive.org/web/20180708234048/https://www.inc.com/encyclopedia/industry-life-cycle.html |archive-date= July 8, 2018 |url-status= live }}</ref>

The [[2011&nbsp;Thailand floods]] damaged the manufacturing plants and impacted hard disk drive cost adversely between 2011 and 2013.<ref>{{cite web
 | url = https://blog.backblaze.com/2012/10/09/backblaze_drive_farming/
 | title = Farming hard drives: how Backblaze weathered the Thailand drive crisis
 | year = 2013
 | access-date = May 23, 2014
 | website = blaze.com
 | archive-url = https://web.archive.org/web/20140625060029/http://blog.backblaze.com/2012/10/09/backblaze_drive_farming/
 | archive-date = June 25, 2014
 | url-status = live
 }}</ref>

In 2019, [[Western Digital]] closed its last Malaysian HDD factory due to decreasing demand, to focus on SSD production.<ref>{{cite web |url=https://www.theregister.com/2018/07/17/western_digital_petaling_jaya_malaysia/ |title=Western Digital formats hard disk drive factory as demand spins down |work=The Register |last=Mellor |first=Chris |date=July 17, 2018 |access-date=July 21, 2021}}</ref> All three remaining HDD manufacturers have had decreasing demand for their HDDs since 2014.<ref>{{cite web |url=https://www.extremetech.com/computing/273849-western-digital-to-close-hdd-plant-increase-ssd-production |title=Western Digital to Close HDD Plant, Increase SSD Production |work=extremetech.com |last=Hruska |first=Joel |date=July 20, 2018 |access-date=July 21, 2021 }}</ref>