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Магнитная запись с подогревом ( HAMR ) - это технология магнитного хранения для значительного увеличения объема данных, которые могут храниться на магнитном устройстве, таком как жесткий диск, путем временного нагрева материала диска во время записи, что делает его более восприимчивым к магнитные эффекты и позволяет записывать в гораздо меньшие области (и гораздо более высокие уровни данных на диске).

Первоначально эта технология считалась чрезвычайно труднодостижимой, и в 2013 году были высказаны сомнения относительно ее осуществимости. [1] Записываемые области должны нагреваться на крошечной области - достаточно маленькой, чтобы дифракция препятствовала использованию обычного сфокусированного лазерного нагрева - и требует цикл нагрева, записи и охлаждения продолжительностью менее 1 наносекунды , а также контроль эффектов повторного точечного нагрева пластин дисковода, контакта диска с головкой и соседних магнитных данных, которые не должны подвергаться влиянию. Эти проблемы потребовали разработки наноразмерных поверхностных плазмонов.(лазер с наведением на поверхность) вместо прямого лазерного нагрева, новые типы стеклянных пластин и терморегулирующих покрытий, которые допускают быстрый точечный нагрев, не влияя на контакт с записывающей головкой или близлежащими данными, новые методы установки нагревательного лазера на приводной головки, а также целый ряд других технических проблем, проблем разработки и управления, которые необходимо было преодолеть. [2] [3]

Планируемый преемник HAMR, известный как магнитная запись с нагретыми точками (HDMR), или запись битового массива, также находится в стадии разработки, хотя ожидается, что он будет доступен не ранее 2025 года или позже. [4] [5] Накопители HAMR имеют тот же форм-фактор (размер и компоновку), что и существующие традиционные жесткие диски, и не требуют каких-либо изменений в компьютере или другом устройстве, на котором они установлены; их можно использовать так же, как существующие жесткие диски. [6]

Накопители HAMR емкостью 20 ТБ были выпущены в январе 2021 года. [7] [8]

Обзор [ править ]

Был разработан ряд технологий, позволяющих увеличивать емкость жестких дисков с незначительным влиянием на стоимость. Чтобы увеличить емкость хранилища в стандартном форм-факторе, необходимо хранить больше данных на меньшем пространстве. Новые технологии для достижения этой цели включают перпендикулярную запись (PMR) , заполненные гелием приводы, черепичную магнитную запись (SMR) ; однако все они, по-видимому, имеют аналогичные ограничения в отношении плотности записи (количество данных, которые могут быть сохранены на магнитной пластине заданного размера). HAMR - это метод, который преодолевает этот предел с магнитными носителями.

Ограничение как традиционной, так и перпендикулярной магнитной записи связано с конкурирующими требованиями читаемости, возможности записи и стабильности (известной как трилемма магнитной записи ). Проблема заключается в том, что для надежного хранения данных для очень маленьких битовых размеров магнитный носитель должен быть изготовлен из материала с очень высокой коэрцитивной силой (способностью сохранять свои магнитные домены и выдерживать любые нежелательные внешние магнитные воздействия). [3] Приводная головка должна преодолеть эту коэрцитивную силу при записи данных. [3] [2] Но по мере увеличения плотности записи размер, занимаемый одним битомданных становится настолько маленьким, что самое сильное магнитное поле, которое может быть создано для записи данных с помощью современной технологии, недостаточно сильное, чтобы преодолеть коэрцитивную силу диска (или, с точки зрения разработки, перевернуть магнитный домен), потому что это невозможно чтобы создать необходимое магнитное поле в такой крошечной области. [3] Фактически, существует точка, в которой становится непрактично или невозможно сделать рабочий диск, потому что магнитная запись больше не возможна в таком маленьком масштабе. [3]

Коэрцитивная сила многих материалов зависит от температуры. Если температура намагниченного объекта временно поднимется выше его температуры Кюри , его коэрцитивная сила станет намного меньше, пока он не остынет. (Это можно увидеть, нагревая намагниченный объект, такой как игла в пламени : когда объект остынет, он потеряет большую часть своей намагниченности.) HAMR использует это свойство магнитных материалов в своих интересах. Крошечный лазер внутри жесткого диска временно нагреваетобласть записи, так что он ненадолго достигает температуры, при которой материал диска временно теряет большую часть своей коэрцитивной силы. Почти сразу же магнитная головка записывает данные на гораздо меньшей площади, чем это было бы возможно в противном случае. Материал снова быстро остывает, и его коэрцитивность возвращается, чтобы предотвратить легкое изменение записанных данных до тех пор, пока они не будут записаны снова. Поскольку одновременно нагревается только крошечная часть диска, нагретая часть быстро охлаждается (менее 1 наносекунды [2] ), и требуется сравнительно небольшая мощность.

Использование обогрева представляло собой серьезные технические проблемы, потому что по состоянию на 2013 год не было четкого способа сосредоточить необходимое тепло на крошечной области, требуемой в рамках ограничений, налагаемых использованием жесткого диска. Время, необходимое для нагрева, записи и охлаждения, составляет около 1 наносекунды , что предполагает использование лазера или аналогичных средств нагрева, но дифракция ограничивает использование света с обычными длинами волн лазера, потому что они обычно не могут фокусироваться на что-либо вроде небольшой области, которая требуется HAMR. для его магнитных доменов. [2] Традиционные плакированные магнитные пластины также не подходят из-за их теплопроводности.свойств, поэтому необходимо разработать новые приводные материалы. [2] Кроме того, необходимо преодолеть широкий спектр других технических проблем, проблем разработки и управления. [2] Компания Seagate Technology , которая играет важную роль в разработке дисков HAMR, отметила, что проблемы включают «подключение полупроводникового диодного лазера к записывающей головке жесткого диска и установку оптики ближнего поля для отвода тепла», а также масштаб использования, который намного больше, чем предыдущее использование оптики ближнего поля. [1] Отраслевой обозреватель IDC stated in 2013 that "The technology is very, very difficult, and there has been a lot of skepticism if it will ever make it into commercial products", with opinions generally that HAMR is unlikely to be commercially available before 2017.[1]

Seagate stated that they overcame the issue of heating focus by developing nano-scale[3] surface plasmons instead of direct laser-based heating.[2] Based on the idea of a waveguide, the laser "travels" along the surface of a guiding material, which is shaped and positioned in order to lead the beam to the area to be heated (about to be written). Diffraction does not adversely affect this kind of wave-guide based focus, so the heating effect can be targeted to the necessary tiny region.[2] The heating issues also require media that can tolerate rapid spot-heating to over 400° C in a tiny area without affecting the contact between the recording head and the platter, or affecting the reliability of the platter and its magnetic coating.[2] The platters are made of a special "HAMR glass" with a coating that precisely controls how heat travels within the platter once it reaches the region being heated - crucial to prevent power waste and undesired heating or erasure of nearby data regions.[2] Running costs are not expected to differ significantly from non-HAMR drives, since the laser only uses a small amount of power - initially described in 2013 as a few tens of milliwatts[1] and more recently in 2017 as "under 200mW" (0.2 W).[5] This is less than 2.5% of the 7 to 12 watts used by common 3.5 inch hard drives.

Seagate first demonstrated working HAMR prototypes in continual use during a 3-day event during 2015.[4] In December 2017 Seagate announced that pre-release drives had been undergoing customer trials with over 40,000 HAMR drives and "millions" of HAMR read/write heads already built, and manufacturing capacity was in place for pilot volumes and first sales of production units to be shipped to key customers in 2018[3] followed by a full market launch of "20 TB+" HAMR drives during 2019,[5][9] with 40 TB hard drives by 2023, and 100 TB drives by around 2030.[3][2] At the same time, Seagate also stated that HAMR prototypes had achieved 2 TB per square inch areal density (having grown at 30% per year over 9 years, with a "near-future" target of 10 TBpsi). Single-head transfer reliability was reported to be "over 2 PB" (equivalent to "over 35 PB in a 5 year life on a 12 TB drive", stated to be "far in excess" of typical use), and heating laser power required "under 200mW" (0.2 W), less than 2.5% of the 8 or more watts typically used by a hard drive motor and its head assembly.[5] Some commentators speculated that HAMR drives would also introduce the use of multiple actuators on hard drives (for speed purposes), as this development was also covered in a Seagate announcement and also stated to be expected in a similar time-scale.[9][10]

History[edit]

  • In 1954, engineers of PL Corporation working for RCA filed a patent which described the basic principle of using heat in conjunction with a magnetic field to record data.[11] This was followed by many other patents in this area with the initial focus on tape storage.
  • In the 1980s, a class of mass storage device called the magneto-optical drive became commercially available, which used essentially the same technique for writing data to a disk. One advantage of magneto-optic recording over purely magnetic storage at that time was that the bit size was defined by the size of the focused laser spot rather than the magnetic field. In 1988, a 5.25-inch magneto-optic disk could hold 650 megabytes of data with a road map to several gigabytes; a single 5.25 inch magnetic disk had a capacity of around 100 megabytes.[12]
  • In late 1992, Sony introduced MiniDisc, a music recording and playback format intended to replace audio cassettes. Recordable MiniDiscs used heat-assisted magnetic recording, but the discs were read optically via the Kerr effect.[13]
  • "late 1990s" - Seagate commenced research and development related to modern HAMR drives.[3]
  • 2006 - Fujitsu demonstrates HAMR.[14]
  • As of 2007, Seagate believed it could produce 300 terabit (37.5 terabyte (TB)) hard disk drives using HAMR technology.[15] Some news sites erroneously reported that Seagate would launch a 300 TB HDD by 2010. Seagate responded to this news stating that 50 terabit per-square-inch density is well past the 2010 timeframe and that this may also involve a combination of Bit Patterned Media.[16]
  • In early 2009 Seagate achieved 250 Gb per square inch using HAMR. This was half of the density achieved via perpendicular magnetic recording (PMR) at that time.[17]
  • Hard disk technology progressed rapidly and as of January 2012, desktop hard disk drives typically had a capacity of 500 to 2000 gigabytes, while the largest-capacity drives were 4 terabytes.[18] It was recognised as early as 2000[19] that the then current technology for hard disk drives would have limitations and that heat-assisted recording was one option to extend the storage capacity.
  • In March 2012 Seagate became the first hard drive maker to achieve the milestone storage density of 1 terabit per square inch using HAMR technology.[20]
  • In October 2012 TDK announced that they had reached a storage density of 1.5 terabit per square inch, using HAMR.[21] This corresponds to 2 TB per platter in a 3.5" drive.
  • November 2013 — Western Digital demonstrates a working HAMR drive,[22] although not yet ready for commercial sales, and Seagate said they expected to begin selling HAMR based drives around 2016.[23]
  • In May 2014, Seagate said they planned to produce low quantities of 6 to 10 TB capacity hard disks in the "near future", but that this would require "a lot of technical investment as you know, it's also a lot of test investment". Though Seagate had not stated that the new hard disks used HAMR, bit-tech.net speculated that they would.[24] Seagate started shipping 8 TB drives around July 2014, but without saying how that capacity was reached; extremetech.com speculated that shingled magnetic recording was used rather than HAMR.[25]
  • In October 2014 TDK predicted that HAMR hard disks could be commercially released in 2015,[26] which did not materialize.
  • At the Intermag 2015 Conference in Beijing, China, from 11 May to 15 May Seagate reported HAMR recording using a plasmonic near field transducer and high anisotropy granular FePt media at an areal density of 1.402 Tb/in².[27]
  • In October 2014 TDK, who supply hard drive components to the major hard drive manufacturers, stated that HAMR drives up to around 15 TB would probably start to become available by 2016,[28] and that the results from a prototype 10,000 rpm Seagate hard drive with a TDK HAMR head suggested that the standard 5 year durability required by enterprise customers was also achievable.
  • In May 2017, Seagate confirmed that they expected to launch HAMR drives commercially "in late 2018", and the announcement was noted by commentators as being the first time that Seagate had committed to such a specific timeframe for a HAMR drive launch. Commentators at the time suggested a likely capacity at launch could be about 16 TB, although specific capacities and models would not be known until then.[29]
  • During December 2017 Seagate announced that HAMR drives had been undergoing pre-pilot trials at customers during 2017 with over 40,000 HAMR drives and "millions" of HAMR read/write heads already built, and manufacturing capacity was in place for pilot volumes in 2018 and a full market launch of "20 TB+" HAMR drives during 2019.[5][9] They also stated that HAMR development had achieved 2 Tb per square inch areal density (growing at 30% per year over 9 years with a "near-future" target of 10 Tbpsi), head reliability of "over 2 PB (petabyte)" per head (equivalent to "over 35 PB in a 5 year life on a 12 TB drive", stated to be "far in excess" of typical use) and heating laser power required "under 200mW" (0.2 Watt), less than 2.5% of the 8 or more watts typically used by a hard drive motor and its head assembly.[5]
    Some commentators speculated on this announcement, that HAMR drives might also see the introduction of multiple actuators on hard drives (for speed purposes), as this development was also covered at a similar time and also stated to be expected in a similar time-scale.[9][10]
  • On 6 November 2018, an updated road map from Seagate was reported as suggesting that 16 TB drives in 2018 might be partner-only, with mass production relating to 20 TB drives in 2020.[30] However, on 27 November, Seagate stated that production drives were already shipping and passing "key customer" tests, and the supply chain existed for volume production, with 20 TB drives on development in 2019 and 40 TB drives expected for 2023. Shortly after the above announcement, on 4 December 2018, Seagate also announced it was undertaking final testing and benchmarking of 16 TB HAMR drives intended for commercial release, after which customers would be asked to qualify them (validate that they perform satisfactorily, and confirm their performance data) before general release, with 20 TB drives planned for 2020. Seagate commented that "These are the same tests that customers use to qualify every new drive", and cover power usage, read and write performance, correct responses to SCSI and SATA commands, and other tests.[31] As of early December 2018, the drives would meeting expectations.[32]
  • At the January 2019 Consumer Electronics Show (CES), Seagate showcased HAMR technology, demonstrating successful read/write tasks using an "Exos" drive with a transparent window to show the drive head in action.
  • In February 2019 AnandTech published an update on HAMR, stating detailed product release plans.[33] According to Seagate, 16 TB single actuator HAMR drives were expected to launch commercially in the first half of 2019. They were specified as "over 250 MB/sec, about 80 Input/output operations per second (IOPS), and 5 IOPS per TB" (IOPS/ TB is an important metric for nearline datastores), with a head lifetime of 4 PB and power in use under 12 W, comparable with existing high performance enterprise hard drives.[33] Beyond that, both 20 TB single actuator HAMR drives, and the company's first dual actuator HAMR drives were expected for 2020. (Dual actuator drives were expected for H2 2019, but were likely to initially use existing perpendicular magnetic recording (PMR) rather than HAMR: their 2019 dual actuator PMR drives were stated to reach around twice the data rate and IOPS of single actuators: 480 MB/s, 169 IOPS, 11 IOPS/ TB for a 14 TB PMR drive).[33]
    Seagate also detailed HAMR's road map after launch: the next generation of technologies enabling HAMR drives up to 24 TB were being tested internally with working platters achieving 2.381 Tb/in2 (3 TB per platter) and 10 Tb/in2 in the laboratory,[33] and the third generation of production devices is aiming for 5 Tb/in2 (40 TB drives) by 2023.[34]
  • In October 2019, analysts suspected that HAMR would be delayed commercially until 2022, with 10-platter hard drives using perpendicular recording (expected to be followed by SMR (Shingled magnetic recording) being used as a stopgap solution.[35]
  • During an April 2020 investor earnings call, Seagate's CEO David Mosley stated that demand was being boosted by the 2020 Coronavirus pandemic, and that they expected 20 TB HAMR drives to ship by the end of 2020.[36]
  • In October 2020 Seagate confirmed their intention to begin shipping 20TB HAMR drives in December 2020, with a target of 50TB by 2026.[37]

Thermomagnetic patterning[edit]

A similar technology to Heat-assisted magnetic recording that has been used mainstream other than for magnetic recording is thermomagnetic patterning. Magnetic coercivity is highly dependent on temperature, and this is the aspect that has been explored, using laser beam to irradiate a permanent magnet film so as to lower its coercivity in the presence of a strong external field that has a magnetization direction opposite to that of the permanent magnet film in order to flip its magnetization. Thus producing a magnetic pattern of opposite magnetizations that can be used for various applications.[38]

Setup[edit]

There are different ways in which the setup can be made, but the underlying principle is still the same. A permanent magnetic strip is deposited on a substrate of silicon or glass, and this is irradiated by a laser beam through a pre-designed mask. The mask is designed specifically for this purpose to prevent the laser beam from irradiating some portions on the magnetic film. This is done in the presence of a very strong magnetic field, which can be generated by a Halbach array.[39] The areas that are exposed/irradiated by the laser beam experience a reduction in their coercivity due to heating by the laser beam, and the magnetization of these portions can be easily flipped by the applied external field, creating the desired patterns

Advantages[edit]

  • Can be used to make many types of patterns
  • Useful for magnetic recording, checkered pattern for micro and nanoscale levitation purpose
  • Cheap, as the laser used typically consumes low power[40]
  • Can be easily implemented
  • Can be used for very fine details depending on the finesse with which the laser is used

Disadvantages[edit]

  • Potential loss of magnetization (if Temp. exceeds Curie temperature)
  • Superparamagnetic nature of ferromagnets at very small size limits how small one can go
  • Boundary issues due to undetermined possibilities at the reversal junction
  • Depth of reversal is currently limited[41]
  • Not too efficient on silicon substrate as silicon acts like a heat sink (better on glass substrate)[40]
  • Residual magnetization is a problem due to the depth of reversal which is limited by the penetration depth of the laser beam

See also[edit]

  • Perpendicular recording
  • Exchange spring media
  • Patterned media
  • Shingled magnetic recording
  • Microwave Assisted Magnetic Recording (MAMR) - Also two-dimensional magnetic recording (TDMR), bit-patterned recording (BPR), and "current perpendicular to plane" giant magnetoresistance (CPP/GMR) heads.

References[edit]

  1. ^ a b c d Stephen Lawson (1 October 2013). "Seagate, TDK show off HAMR to jam more data into hard drives". Computerworld. Retrieved 30 January 2015.
  2. ^ a b c d e f g h i j k "Seagate HAMR technical brief" (PDF).
  3. ^ a b c d e f g h i Hagedoorn, Hilbert. "Backblaze on HAMR HDD Technology". Guru3D.com.
  4. ^ a b "Seagate demos HAMR HDDs, vows to start shipments in 2017".
  5. ^ a b c d e f Re, Mark (23 October 2017). "HAMR: the Next Leap Forward is Now".
  6. ^ https://blog.seagate.com/intelligent/hamr-next-leap-forward-now : "HAMR is transparent to host; passed customer testing using standard code"
  7. ^ Shilov, Anton (23 January 2021). "Seagate Ships 20TB HAMR HDDs Commercially, Increases Shipments of Mach.2 Drives". www.tomshardware.com. Retrieved 26 February 2021.
  8. ^ Lee, Aaron; Tsai, Joseph (15 January 2021). "Seagate to expand HDD storage capacity". www.digitimes.com. Retrieved 26 February 2021.
  9. ^ a b c d Feist, Jason (18 December 2017). "Multi Actuator Technology: A New Performance Breakthrough".
  10. ^ a b https://www.anandtech.com/show/12169/seagates-multi-actuator-technology-to-double-hdd-performance : "Seagate says that the Multi-Actuator Technology is to be deployed on products in the near future, but does not disclose when exactly. As the company's blog post on the matter mentions both MAT and HAMR, it is highly likely that commercial hard drives featuring HAMR due in late 2019 will also have two actuators on a single pivot. At the same time, it does not mean that the MAT is not going to find itself a place in products using conventional PMR."
  11. ^ US patent 2915594, Burns Jr., Leslie L. & Keizer, Eugene O., "Magnetic Recording System", published 1959-12-01, assigned to Radio Corporation of America 
  12. ^ "ST-41200N". seagate.com. Archived from the original on 24 March 2012. Retrieved 30 January 2015. CS1 maint: discouraged parameter (link)
  13. ^ Jan Maes, Marc Vercammen. Digital Audio Technology: A Guide to CD, MiniDisc, SACD, DVD(A), MP3 and DAT. pp. 238–251. ISBN 9781136118623.
  14. ^ "Seagate hits 1 terabit per square inch, 60 TB hard drives on their way". ExtremeTech. Retrieved 30 January 2015.
  15. ^ "Inside Seagate's R&D Labs". WIRED. 2007. Retrieved 30 January 2015.
  16. ^ "300 teraBITS is not 300 TB! And 3 TB isn't 300 TB!". dvhardware.net. Retrieved 30 January 2015.
  17. ^ "Laser-Heated Hard Drives Could Break Data Density Barrier". ieee.org. Archived from the original on 10 September 2015. Retrieved 30 January 2015.
  18. ^ "Seagate Is The First Manufacturer To Break The Capacity Ceiling With A New 4 TB GoFlex Desk Drive". seagate.com. 7 September 2011. Archived from the original on 30 January 2015. Retrieved 30 January 2015. CS1 maint: discouraged parameter (link)
  19. ^ Kryder, M.H., "Magnetic recording beyond the superparamagnetic limit," Magnetics Conference, 2000. INTERMAG 2000 Digest of Technical Papers. 2000 IEEE International , vol., no., pp. 575, 4–8 April 2005 doi:10.1109/INTMAG.2000.872350
  20. ^ "Seagate Reaches 1 Terabit Per Square Inch Milestone In Hard Drive Storage With New Technology Demonstration | News Archive | Seagate US". Seagate.com.
  21. ^ "[CEATEC] TDK Claims HDD Areal Density Record". Nikkei Technology Online. 2 October 2013. Retrieved 30 January 2015.
  22. ^ "Western Digital Demos World's First Hard Drive with HAMR Technology - X-bit labs". xbitlabs.com. 13 November 2013. Archived from the original on 12 September 2014. Retrieved 30 January 2015. CS1 maint: discouraged parameter (link)
  23. ^ Bill Oliver. "WD Demos Future HDD Storage Tech: 60 TB Hard Drives". Tom's IT Pro. Archived from the original on 9 June 2015. Retrieved 30 January 2015.
  24. ^ "Seagate hints at 8 TB, 10 TB hard drive launch plans". bit-tech. Retrieved 30 January 2015.
  25. ^ "Seagate starts shipping 8 TB hard drives, with 10 TB and HAMR on the horizon". ExtremeTech. Retrieved 30 January 2015.
  26. ^ "TDK: HAMR technology could enable 15 TB HDDs already in 2015". kitguru.net. Retrieved 30 January 2015.
  27. ^ Ju, Ganping; Peng, Yingguo; Chang, Eric K. C.; Ding, Yinfeng; Wu, Alexander Q.; Zhu, Xiaobin; Kubota, Yukiko; Klemmer, Timothy J.; Amini, Hassib; Gao, Li; Fan, Zhaohui; Rausch, Tim; Subedi, Pradeep; Ma, Minjie; Kalarickal, Sangita; Rea, Chris J.; Dimitrov, Dimitar V.; Huang, Pin-Wei; Wang, Kangkang; Chen, Xi; Peng, Chubing; Chen, Weibin; Dykes, John W.; Seigler, Mike A.; Gage, Edward C.; Chantrell, Roy; Thiele, Jan-Ulrich (5 November 2015). "High Density Heat-Assisted Magnetic Recording Media and Advanced Characterization—Progress and Challenges". IEEE Transactions on Magnetics. 51 (11): 2439690. Bibcode:2015ITM....5139690J. doi:10.1109/TMAG.2015.2439690.
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External links[edit]

  • 2002 Information by Seagate about HAMR
  • Seagate HAMR technical brief describing what needed to be done to develop HAMR, as at 2017