{"id":97879,"date":"2020-10-22T20:43:09","date_gmt":"2020-10-22T18:43:09","guid":{"rendered":"https:\/\/prohoster.info\/blog\/administrirovanie\/tehnologii-magnitnoj-zapisi-hdd-prosto-o-slozhnom"},"modified":"2020-10-22T20:43:09","modified_gmt":"2020-10-22T18:43:09","slug":"tehnologii-magnitnoj-zapisi-hdd-prosto-o-slozhnom","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/administrirovanie\/tehnologii-magnitnoj-zapisi-hdd-prosto-o-slozhnom","title":{"rendered":"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/bd1ce14af7aeed6c2c698d047ee2c036.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nPrv\u00fd na svete pevn\u00fdm diskom, IBM RAMAC 305, ktor\u00fd bol predstaven\u00fd v roku 1956, mal kapacitu iba 5 MB d\u00e1t a v\u00e1\u017eil 970 kg, pri\u010dom jeho rozmery sa podobali priemyseln\u00e9mu chladi\u010du. Modern\u00e9 podnikov\u00e9 vlajkov\u00e9 lode sa m\u00f4\u017eu pochv\u00e1li\u0165 kapacitou u\u017e 20 TB. Predstavte si: pred 64 rokmi by na zaznamenanie tak\u00e9ho mno\u017estva inform\u00e1ci\u00ed bolo potrebn\u00fdch viac ako 4 mili\u00f3ny RAMAC 305, pri\u010dom plocha potrebn\u00e1 na ich uskladnenie by prevy\u0161ovala 9 \u0161tvorcov\u00fdch kilometrov, zatia\u013e \u010do dnes sta\u010d\u00ed mal\u00e1 krabi\u010dka s hmotnos\u0165ou pribli\u017ene 700 gramov! V mnohom sa tak\u00fato neuverite\u013en\u00fa hustotu ukladania podarilo dosiahnu\u0165 v\u010faka vylep\u0161eniu met\u00f3d magnetick\u00e9ho z\u00e1znamu.<noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><br \/>\n\u0164a\u017eko tomu uveri\u0165, no kon\u0161trukcia pevn\u00fdch diskov sa podstatne nezmenila u\u017e takmer 40 rokov, po\u010dn\u00fac rokom 1983: pr\u00e1ve vtedy bol uveden\u00fd prv\u00fd 3,5-palcov\u00fd disk RO351, ktor\u00fd vyvinula \u0161k\u00f3tska spolo\u010dnos\u0165 Rodime. Tento mal\u00fd disk mal dve magnetick\u00e9 platne po 10 MB ka\u017ed\u00e1, teda bol schopn\u00fd poja\u0165 dvakr\u00e1t viac d\u00e1t ako aktualizovan\u00fd ST-412 s rozmerom 5,25 palca, ktor\u00fd bol vydan\u00fd spolo\u010dnos\u0165ou Seagate v tom istom roku pre osobn\u00e9 po\u010d\u00edta\u010de IBM 5160.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/dd90bee93790a14064a573f9e086ff71.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Rodime RO351 \u2014 prv\u00fd na svete 3,5-palcov\u00fd disk<\/i><\/p>\n<p>Napriek inovat\u00edvnosti a kompaktn\u00fdm rozmerom sa RO351 pri svojom uveden\u00ed na trh uk\u00e1zal ako prakticky nepotrebn\u00fd, a v\u0161etky \u010fal\u0161ie pokusy Rodime usadi\u0165 sa na trhu diskov zlyhali, \u010do viedlo v roku 1991 k ukon\u010deniu \u010dinnosti spolo\u010dnosti, ktor\u00e1 sa musela zbavi\u0165 prakticky v\u0161etk\u00fdch svojich akt\u00edv a zn\u00ed\u017ei\u0165 po\u010det zamestnancov na minimum. Av\u0161ak Rodime nebolo s\u00faden\u00e9 skrachova\u0165: \u010doskoro sa na \u0148u za\u010dali obraca\u0165 najv\u00e4\u010d\u0161\u00ed v\u00fdrobcovia diskov, ktor\u00ed mali z\u00e1ujem o licenciu na pou\u017eitie patentovan\u00e9ho form\u00e1tu vyvinut\u00e9ho \u0161k\u00f3tmi. V s\u00fa\u010dasnosti je 3,5 palca be\u017en\u00fdm \u0161tandardom v\u00fdroby ako pre spotrebite\u013esk\u00e9 HDD, tak aj pre podnikov\u00e9 \u00falo\u017eisk\u00e1.<\/p>\n<p>S pr\u00edchodom neur\u00f3nov\u00fdch siet\u00ed, Deep Learningu a internetu vec\u00ed (IoT) objem vytv\u00e1ran\u00fdch d\u00e1t \u013eu\u010fmi vzr\u00e1stol explos\u00edvne. Pod\u013ea odhadov analytickej agent\u00fary IDC dosiahne do roku 2025 mno\u017estvo inform\u00e1ci\u00ed generovan\u00fdch ako samotn\u00fdmi \u013eu\u010fmi, tak aj okolit\u00fdmi zariadeniami 175 zettabajtov (1 ZB = 10^21 bajtov), a to aj napriek tomu, \u017ee v roku 2019 to predstavovalo 45 ZB, v roku 2016 - 16 ZB a v roku 2006 celkov\u00fd objem d\u00e1t vyprodukovan\u00fdch od za\u010diatku v\u0161eobecnej hist\u00f3rie nepresiahol 0,16 (!) ZB. S informa\u010dn\u00fdm v\u00fdbuchom pom\u00e1haj\u00fa modern\u00e9 technol\u00f3gie, medzi ktor\u00fdmi maj\u00fa vylep\u0161en\u00e9 met\u00f3dy z\u00e1pisu d\u00e1t v\u00fdznamn\u00e9 miesto.<\/p>\n<h2>LMR, PMR, CMR a TDMR: ak\u00fd je rozdiel?<\/h2>\n<p>\nPrinc\u00edp fungovania pevn\u00fdch diskov je pomerne jednoduch\u00fd. Ten\u0161ie kovov\u00e9 dosky pokryt\u00e9 vrstvou ferromagnetick\u00e9ho materi\u00e1lu (kry\u0161talick\u00e1 l\u00e1tka schopn\u00e1 udr\u017eiava\u0165 magnetiz\u00e1ciu aj bez vonkaj\u0161ieho magnetick\u00e9ho po\u013ea pri teplote pod Curieho bodom) sa pohybuj\u00fa vo\u010di blokom zapisovac\u00edch hl\u00e1v vysokou r\u00fdchlos\u0165ou (5400 ot\u00e1\u010dok za min\u00fatu alebo viac). Pri dodan\u00ed elektrick\u00e9ho pr\u00fadu na zapisovaciu hlavu vznik\u00e1 striedav\u00e9 magnetick\u00e9 pole, ktor\u00e9 men\u00ed smer vektora magnetiz\u00e1cie dom\u00e9n (diskr\u00e9tnych oblast\u00ed l\u00e1tky) ferromagnetika. \u010c\u00edtanie d\u00e1t sa uskuto\u010d\u0148uje bu\u010f prostredn\u00edctvom javu elektromagnetickej indukcie (pohyb dom\u00e9n vo\u010di sn\u00edma\u010du sp\u00f4sobuje vznik striedav\u00e9ho elektrick\u00e9ho pr\u00fadu), alebo prostredn\u00edctvom obrovsk\u00e9ho magnetorezist\u00edvneho efektu (pod vplyvom magnetick\u00e9ho po\u013ea sa men\u00ed elektrick\u00fd odpor sn\u00edma\u010da), ako je realizovan\u00e9 v modern\u00fdch \u00falo\u017eisk\u00e1ch. Ka\u017ed\u00e1 dom\u00e9na k\u00f3duje jeden bit inform\u00e1cie, pri\u010dom prij\u00edma logick\u00fa hodnotu \u201e0\u201c alebo \u201e1\u201c v z\u00e1vislosti od smeru vektora magnetiz\u00e1cie.<\/p>\n<p>Dlho sa na pevn\u00e9 disky pou\u017e\u00edvala met\u00f3da pozdl\u017en\u00e9ho magnetick\u00e9ho z\u00e1znamu (Longitudinal Magnetic Recording, LMR), pri ktorej vektor magnetiz\u00e1cie dominoval v rovine magnetickej platne. Napriek relat\u00edvnej jednoduchosti realiz\u00e1cie mala t\u00e1to technol\u00f3gia v\u00fdznamn\u00fa nev\u00fdhodu: aby sa prekonala koercitivita (prechod magnetick\u00fdch \u010dast\u00edc do jednodom\u00e9nov\u00e9ho stavu), musela sa medzi dr\u00e1hami necha\u0165 zna\u010dn\u00e1 bufferov\u00e1 z\u00f3na (tzv. guard space \u2014 ochrann\u00fd priestor). V d\u00f4sledku toho maxim\u00e1lna hustota z\u00e1znamu, ktor\u00fa sa podarilo dosiahnu\u0165 na sklonku tejto technol\u00f3gie, dosahovala len 150 Gbit\/dal.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/a032ba1bcbb118ffd46ff29853a0cad5.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nV roku 2010 bola LMR prakticky \u00faplne vytla\u010den\u00e1 PMR (Perpendicular Magnetic Recording \u2014 kolm\u00e1 magnetick\u00e1 zaznamen\u00e1vanie). Hlavn\u00fd rozdiel tejto technol\u00f3gie od pozdl\u017en\u00e9ho magnetick\u00e9ho z\u00e1znamu spo\u010d\u00edva v tom, \u017ee vektor magnetickej orient\u00e1cie ka\u017ed\u00e9ho domina le\u017e\u00ed pod uhlom 90\u00b0 na povrchu magnetickej platne, \u010do umo\u017enilo podstatne skr\u00e1ti\u0165 vzdialenos\u0165 medzi dr\u00e1hami. <\/p>\n<p>V\u010faka tomu sa podarilo v\u00fdrazne zv\u00fd\u0161i\u0165 hustotu z\u00e1znamu \u00fadajov (a\u017e do 1 Tbit\/dal v s\u00fa\u010dasn\u00fdch zariadeniach), pri\u010dom neboli obetovan\u00e9 r\u00fdchlostn\u00e9 charakteristiky a spo\u013eahlivos\u0165 pevn\u00fdch diskov. V s\u00fa\u010dasnosti je kolm\u00e1 magnetick\u00e1 zaznamen\u00e1vanie dominantn\u00e1 na trhu, a preto sa \u010dasto naz\u00fdva aj CMR (Conventional Magnetic Recording \u2014 be\u017en\u00fd magnetick\u00fd z\u00e1znam). Treba v\u0161ak ch\u00e1pa\u0165, \u017ee medzi PMR a CMR nie je \u017eiadny rozdiel \u2014 je to len in\u00fd variant n\u00e1zvu.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/1ac5e7ecee7774e9c0461bb80fef1b57.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nPri sk\u00faman\u00ed technick\u00fdch parametrov modern\u00fdch pevn\u00fdch diskov sa m\u00f4\u017eete tie\u017e stretn\u00fa\u0165 s tajomnou skratkou TDMR. Najm\u00e4 t\u00fato technol\u00f3giu pou\u017e\u00edvaj\u00fa \u00falo\u017eisk\u00e1 podnikovej triedy <noindex><a rel=\"nofollow\" href=\"https:\/\/documents.westerndigital.com\/content\/dam\/doc-library\/en_us\/assets\/public\/western-digital\/product\/data-center-drives\/ultrastar-dc-hc500-series\/data-sheet-ultrastar-dc-hc530.pdf\">Western Digital Ultrastar 500. s\u00e9ria<\/a><\/noindex>. Z fyzik\u00e1lneho h\u013eadiska TDMR (\u010do sa roz\u0161iruje ako Two Dimensional Magnetic Recording \u2014 dvojdimenzion\u00e1lny magnetick\u00fd z\u00e1znam) sa nijako nel\u00ed\u0161i od zn\u00e1mej PMR: ako v\u017edy, m\u00e1me \u010do do \u010dinenia s neprekr\u00fdvaj\u00facimi sa dr\u00e1hami, pri\u010dom dom\u00e9ny s\u00fa orientovan\u00e9 kolmo na rovinu magnetick\u00fdch platn\u00ed. Rozdiel medzi technol\u00f3giami spo\u010d\u00edva v pr\u00edstupe k \u010d\u00edtaniu inform\u00e1ci\u00ed.<\/p>\n<p>V bloku magnetick\u00fdch hl\u00e1v pevn\u00fdch diskov, vytvoren\u00fdch pomocou technol\u00f3gie TDMR, pripad\u00e1 na ka\u017ed\u00fa zapisovaciu hlavu dva \u010d\u00edtaj\u00face senzory, ktor\u00e9 vykon\u00e1vaj\u00fa s\u00fa\u010dasn\u00e9 \u010d\u00edtanie \u00fadajov z ka\u017ed\u00e9ho prech\u00e1dzaj\u00faceho traktu. Tak\u00e1to redundantnos\u0165 umo\u017e\u0148uje HDD kontrol\u00f3ru efekt\u00edvne filtrova\u0165 elektromagnetick\u00fd \u0161um, ktor\u00e9ho vznik sp\u00f4sobuje medzi trakov\u00fa interferenciu (Intertrack Interference, ITI).<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/d0faec7be634a35776c87ecebb3d872e.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nRie\u0161enie probl\u00e9mu s ITI zabezpe\u010duje dve mimoriadne d\u00f4le\u017eit\u00e9 v\u00fdhody:<\/p>\n<ol>\n<li>zni\u017eovanie koeficientu ru\u0161enia umo\u017e\u0148uje zv\u00fd\u0161i\u0165 hustotu z\u00e1pisu zmen\u0161en\u00edm vzdialenosti medzi traktami, \u010d\u00edm sa dosiahne n\u00e1rast celkovej kapacity a\u017e o 10 % v porovnan\u00ed s be\u017en\u00fdm PMR;<\/li>\n<li>v kombin\u00e1cii s technol\u00f3giou RVS a trojpozicion\u00e1lnym mikroaktuatorom, TDMR efekt\u00edvne odol\u00e1va rota\u010dnej vibr\u00e1cii sp\u00f4sobenej prev\u00e1dzkou pevn\u00fdch diskov, \u010do napom\u00e1ha dosiahnu\u0165 stabiln\u00fa \u00farove\u0148 v\u00fdkonu aj v najn\u00e1ro\u010dnej\u0161\u00edch podmienkach prev\u00e1dzky.<\/li>\n<\/ol>\n<p><\/p>\n<h2>\u010co je to SMR a ako sa to pou\u017e\u00edva?<\/h2>\n<p>\nVe\u013ekosti zapisovacej hlavy s\u00fa pribli\u017ene 1,7 kr\u00e1t v\u00e4\u010d\u0161ie v porovnan\u00ed s ve\u013ekos\u0165ou \u010d\u00edtaj\u00faceho senzora. Tak\u00e1to v\u00fdznamn\u00e1 rozdielnos\u0165 sa d\u00e1 vysvetli\u0165 jednoducho: ak by sa zapisovac\u00ed modul vyrobil e\u0161te men\u0161\u00edm, sily magnetick\u00e9ho po\u013ea, ktor\u00e9 by mohol generova\u0165, by boli nedostato\u010dn\u00e9 na magnetiz\u00e1ciu dom\u00e9n feromagnetick\u00e9ho vrstvy, a teda \u00fadaje jednoducho nebud\u00fa ulo\u017een\u00e9. V pr\u00edpade \u010d\u00edtaj\u00faceho senzora sa tento probl\u00e9m nevyskytuje. Navy\u0161e: jeho miniaturiz\u00e1cia umo\u017e\u0148uje \u010fal\u0161ie zn\u00ed\u017eenie vplyvu vy\u0161\u0161ie uvedenej ITI na proces \u010d\u00edtania inform\u00e1ci\u00ed.<\/p>\n<p>Tento fakt sa stal z\u00e1kladom \u010derpenej magnetickej z\u00e1pisu (Shingled Magnetic Recording, SMR). Po\u010fme sa pozrie\u0165, ako to funguje. Pri pou\u017e\u00edvan\u00ed tradi\u010dn\u00e9ho PMR sa zapisovacia hlava pos\u00fava vo\u010di ka\u017ed\u00e9mu predch\u00e1dzaj\u00facemu traku na vzdialenos\u0165 rovnaj\u00facu sa jej \u0161\u00edrke + \u0161\u00edrka ochrann\u00e9ho priestoru (guard space).<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/31ff088be66ac435d2875e15fd1f5b67.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nPri pou\u017eit\u00ed \u0161indelov\u00e9ho sp\u00f4sobu magnetick\u00e9ho z\u00e1pisu sa p\u00edsacia hlava pos\u00fava dopredu len o \u010das\u0165 svojej \u0161\u00edrky, tak\u017ee ka\u017ed\u00fd predch\u00e1dzaj\u00faci p\u00e1s je \u010diasto\u010dne prep\u00edsan\u00fd nasleduj\u00facim: magnetick\u00e9 stopy sa prekr\u00fdvaj\u00fa podobne ako stre\u0161n\u00e9 \u0161indle. Tak\u00fdto pr\u00edstup umo\u017e\u0148uje dodato\u010dne zv\u00fd\u0161i\u0165 hustotu z\u00e1pisu, pri\u010dom sa z\u00edska a\u017e 10% kapacity bez negat\u00edvneho vplyvu na proces \u010d\u00edtania. Ako pr\u00edklad m\u00f4\u017eeme uvies\u0165 <noindex><a rel=\"nofollow\" href=\"https:\/\/documents.westerndigital.com\/content\/dam\/doc-library\/en_us\/assets\/public\/western-digital\/product\/data-center-drives\/ultrastar-dc-hc600-series\/data-sheet-ultrastar-dc-hc650.pdf\">Western Digital Ultrastar DC HC 650<\/a><\/noindex> \u2014 prv\u00e9 na svete 3,5-palcov\u00e9 pam\u00e4\u0165ov\u00e9 jednotky s kapacitou 20 TB a rozhran\u00edm SATA\/SAS, ktor\u00fdch vznik bol umo\u017enen\u00fd pr\u00e1ve v\u010faka novej technol\u00f3gii magnetick\u00e9ho z\u00e1pisu. T\u00fdmto sp\u00f4sobom prechod na SMR disky umo\u017e\u0148uje zv\u00fd\u0161i\u0165 hustotu ukladania d\u00e1t v rovnak\u00fdch stojanoch s minim\u00e1lnymi n\u00e1kladmi na moderniz\u00e1ciu IT infra\u0161trukt\u00fary.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/0a80169925f129320348e2789cf42e35.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nNapriek takejto v\u00fdznamnej v\u00fdhode m\u00e1 SMR aj o\u010dividn\u00fa nev\u00fdhodu. Ke\u010f\u017ee sa magnetick\u00e9 stopy prekr\u00fdvaj\u00fa, pri aktualiz\u00e1cii \u00fadajov bude potrebn\u00e9 prep\u00edsa\u0165 nielen po\u017eadovan\u00fa \u010das\u0165, ale aj v\u0161etky nasleduj\u00face stopy v r\u00e1mci magnetickej platne, ktorej objem m\u00f4\u017ee presiahnu\u0165 2 terabajty, \u010do m\u00f4\u017ee vies\u0165 k v\u00e1\u017enemu poklesu v\u00fdkonu.<\/p>\n<p>Rie\u0161en\u00edm tejto problematiky je zl\u00fa\u010denie ur\u010dit\u00e9ho po\u010dtu st\u00f4p do samostatn\u00fdch skup\u00edn, naz\u00fdvan\u00fdch z\u00f3ny. Hoci tak\u00fdto pr\u00edstup k organiz\u00e1cii ukladania \u00fadajov trochu zni\u017euje celkov\u00fa kapacitu HDD (preto\u017ee medzi z\u00f3nami je potrebn\u00e9 zachov\u00e1va\u0165 dostato\u010dn\u00e9 pr\u00e1zdne miesta, ktor\u00e9 zabra\u0148uj\u00fa prep\u00edsaniu st\u00f4p z susedn\u00fdch skup\u00edn), umo\u017e\u0148uje to v\u00fdrazne ur\u00fdchli\u0165 proces aktualiz\u00e1cie \u00fadajov, preto\u017ee sa teraz z\u00fa\u010dast\u0148uje iba obmedzen\u00fd po\u010det st\u00f4p.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/5b7dc2182759c1ebeb559cfb32972544.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n\u0160indelov\u00fd magnetick\u00fd z\u00e1pis predpoklad\u00e1 nieko\u013eko variant realiz\u00e1cie:<\/p>\n<ul>\n<li><b>Drive Managed SMR (SMR riaden\u00e1 diskom)<\/b><\/li>\n<\/ul>\n<p>\nHlavnou v\u00fdhodou je absencia potreby modifik\u00e1cie softv\u00e9ru a\/alebo hardv\u00e9ru hostite\u013ea, preto\u017ee riadenie procesu z\u00e1pisu \u00fadajov preber\u00e1 ovl\u00e1da\u010d HDD. Tak\u00e9to disky m\u00f4\u017eu by\u0165 pripojen\u00e9 k akejko\u013evek s\u00fastave, v ktorej je pr\u00edtomn\u00e9 potrebn\u00e9 rozhranie (SATA alebo SAS), po \u010dom je pam\u00e4\u0165ov\u00e1 jednotka okam\u017eite pripraven\u00e1 na pr\u00e1cu.<\/p>\n<p>Nev\u00fdhodou tohoto p\u0159\u00edstupu je prom\u011bnlivost \u00farovn\u011b v\u00fdkonu, co\u017e zp\u016fsobuje, \u017ee Drive Managed SMR je nevhodn\u00fd pro podnikov\u00e9 aplikace, kde je konzistence v\u00fdkonu syst\u00e9mu kriticky d\u016fle\u017eit\u00e1. P\u0159esto se tyto disky osv\u011bd\u010duj\u00ed v sc\u00e9n\u00e1\u0159\u00edch, kde je k dispozici dostatek \u010dasu na prov\u00e1d\u011bn\u00ed pozad\u00ed defragmentace dat. Nap\u0159\u00edklad DMSMR \u00falo\u017ei\u0161t\u011b <noindex><a rel=\"nofollow\" href=\"https:\/\/documents.westerndigital.com\/content\/dam\/doc-library\/en_us\/assets\/public\/western-digital\/product\/internal-drives\/wd-red-hdd\/product-brief-western-digital-wd-red-hdd.pdf\">WD Red<\/a><\/noindex>, optimalizovan\u00e9 pro vyu\u017eit\u00ed v mal\u00fdch NAS se 8 z\u00e1suvkami, budou skv\u011blou volbou pro archivaci nebo z\u00e1lohovac\u00ed syst\u00e9m, kter\u00fd p\u0159edpokl\u00e1d\u00e1 dlouhodob\u00e9 uchov\u00e1n\u00ed z\u00e1loh.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/39c9fc7858441835e60ea27f88d21b59.png\" style=\"display:block;margin: 0 auto;\" \/><\/p>\n<ul>\n<li><b>Host Managed SMR (SMR \u0159\u00edzen\u00fd hostitelem)<\/b><\/li>\n<\/ul>\n<p>\nHost Managed SMR je nejpreferovan\u011bj\u0161\u00ed variantou implementace z\u00f3nov\u00e9ho z\u00e1pisu pro podnikov\u00e9 prost\u0159ed\u00ed. V tomto p\u0159\u00edpad\u011b m\u00e1 spr\u00e1va datov\u00fdch tok\u016f a operac\u00ed \u010dten\u00ed\/z\u00e1pisu na starosti samotn\u00fd hostitelsk\u00fd syst\u00e9m, kter\u00fd k tomu vyu\u017e\u00edv\u00e1 roz\u0161\u00ed\u0159en\u00ed rozhran\u00ed ATA (Zoned Device ATA Command Set, ZAC) a SCSI (Zoned Block Commands, ZBC), vyvinut\u00e1 v\u00fdbory INCITS T10 a T13.<\/p>\n<p>P\u0159i pou\u017eit\u00ed HMSMR je ve\u0161ker\u00e1 dostupn\u00e1 kapacita disku rozd\u011blena na oblasti dvou typ\u016f: Conventional Zones (b\u011b\u017en\u00e9 z\u00f3ny), kter\u00e9 slou\u017e\u00ed k ukl\u00e1d\u00e1n\u00ed metadat a voln\u00e9mu z\u00e1pisu (ve skute\u010dnosti funguj\u00ed jako vyrovn\u00e1vac\u00ed pam\u011b\u0165), a Sequential Write Required Zones (z\u00f3ny pro sekven\u010dn\u00ed z\u00e1pis), kter\u00e9 zab\u00edraj\u00ed v\u011bt\u0161inu celkov\u00e9 kapacity pevn\u00e9ho disku, ve kter\u00fdch jsou data zapisov\u00e1na p\u0159\u00edsn\u011b sekven\u010dn\u011b. Neuspo\u0159\u00e1dan\u00e1 data jsou ukl\u00e1d\u00e1na do vyrovn\u00e1vac\u00ed pam\u011bti, odkud mohou b\u00fdt pot\u00e9 p\u0159esunuta do p\u0159\u00edslu\u0161n\u00e9 z\u00f3ny sekven\u010dn\u00edho z\u00e1pisu. D\u00edky tomu jsou v\u0161echny fyzick\u00e9 sektory zapisov\u00e1ny sekven\u010dn\u011b v radi\u00e1ln\u00edm sm\u011bru a p\u0159episov\u00e1ny pouze po cyklick\u00e9m p\u0159esunu, co\u017e umo\u017e\u0148uje dos\u00e1hnout stabiln\u00edho a p\u0159edv\u00eddateln\u00e9ho v\u00fdkonu syst\u00e9mu. P\u0159itom HMSMR disky podporuj\u00ed p\u0159\u00edkazy pro n\u00e1hodn\u00e9 \u010dten\u00ed podobn\u011b jako \u00falo\u017ei\u0161t\u011b vyu\u017e\u00edvaj\u00edc\u00ed standardn\u00ed PMR.<\/p>\n<p>Host Managed SMR je implementov\u00e1no v pevn\u00fdch disc\u00edch podnikov\u00e9 t\u0159\u00eddy <noindex><a rel=\"nofollow\" href=\"https:\/\/www.westerndigital.com\/products\/data-center-drives\/ultrastar-dc-hc600-series-hdd\">Western Digital Ultrastar HC DC s\u00e9rie 600<\/a><\/noindex>.<\/p>\n<p><img decoding=\"async\" alt=\"Technol\u00f3gie magnetick\u00e9ho z\u00e1pisu HDD: jednoducho o zlo\u017eit\u00fdch veciach\" src=\"\/wp-content\/uploads\/2020\/10\/f9ab1ddb6866dacd7f61890ed61c07f3.png\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nRada zah\u0155\u0148a vysokokapacitn\u00e9 SATA a SAS \u00falo\u017eisk\u00e1 ur\u010den\u00e9 pre hyper\u0161k\u00e1lovacie centr\u00e1 d\u00e1t. Podpora Host Managed SMR v\u00fdznamne roz\u0161iruje rozsah pou\u017eitia t\u00fdchto pevn\u00fdch diskov: okrem z\u00e1lohovac\u00edch syst\u00e9mov s\u00fa ide\u00e1lne aj pre cloudov\u00e9 \u00falo\u017eisk\u00e1, CDN alebo streamovacie platformy. Vysok\u00e1 kapacita pevn\u00fdch diskov umo\u017e\u0148uje v\u00fdznamne zv\u00fd\u0161i\u0165 hustotu ukladania (v t\u00fdch ist\u00fdch skrink\u00e1ch) pri minim\u00e1lnych n\u00e1kladoch na upgrade, a n\u00edzka spotreba energie (nie viac ako 0,29 W na ka\u017ed\u00fd terabajt ulo\u017een\u00fdch inform\u00e1ci\u00ed) a tepeln\u00e9 vy\u017earovanie (v priemere o 5 \u00b0C ni\u017e\u0161ie ako u konkurencie) \u010falej zni\u017euje prev\u00e1dzkov\u00e9 n\u00e1klady na \u00fadr\u017ebu d\u00e1tov\u00e9ho centra.<\/p>\n<p>Jedinou nev\u00fdhodou HMSMR je relat\u00edvna zlo\u017eitosti implement\u00e1cie. D\u00f4vodom je, \u017ee v s\u00fa\u010dasnosti \u017eiadny opera\u010dn\u00fd syst\u00e9m alebo aplik\u00e1cia nefunguj\u00fa s tak\u00fdmito \u00falo\u017eiskami \"priamo z krabice\", preto je pre prisp\u00f4sobenie IT infra\u0161trukt\u00fary potrebn\u00e1 zna\u010dn\u00e1 zmena softv\u00e9rov\u00e9ho stacku. To sa najm\u00e4 t\u00fdka samotn\u00e9ho opera\u010dn\u00e9ho syst\u00e9mu, \u010do v podmienkach modern\u00fdch d\u00e1tov\u00fdch centier, ktor\u00e9 pou\u017e\u00edvaj\u00fa viacjadrov\u00e9 a viacsocketov\u00e9 servery, predstavuje dos\u0165 zlo\u017eit\u00fa \u00falohu. Viac inform\u00e1ci\u00ed o mo\u017enostiach realiz\u00e1cie podpory Host Managed SMR m\u00f4\u017eete n\u00e1js\u0165 na \u0161pecializovanom webe <noindex><a rel=\"nofollow\" href=\"http:\/\/zonedstorage.io\/\">ZonedStorage.io<\/a><\/noindex>, ktor\u00fd sa zaober\u00e1 ot\u00e1zkami zon\u00e1lneho ukladania d\u00e1t. Inform\u00e1cie zhroma\u017eden\u00e9 tu v\u00e1m pom\u00f4\u017eu predbe\u017ene zhodnoti\u0165 pripravenos\u0165 va\u0161ej IT infra\u0161trukt\u00fary na prechod na zon\u00e1lne syst\u00e9my ukladania.<\/p>\n<ul>\n<li><b>Host Aware SMR (SMR podporovan\u00e1 hos\u0165om)<\/b><\/li>\n<\/ul>\n<p>\nZariadenia s podporou Host Aware SMR kombinuj\u00fa pohodlie a flexibilitu Drive Managed SMR s vysokou r\u00fdchlos\u0165ou z\u00e1pisu Host Managed SMR. Tak\u00e9to \u00falo\u017eisk\u00e1 s\u00fa sp\u00e4tne kompatibiln\u00e9 so star\u0161\u00edmi syst\u00e9mami ukladania a m\u00f4\u017eu fungova\u0165 bez priamej kontroly zo strany hostite\u013ea, av\u0161ak v tomto pr\u00edpade, rovnako ako pri pr\u00e1ci s DMSMR diskami, sa ich v\u00fdkon st\u00e1va nepr predict\u00edvnym.<\/p>\n<p>Podobne ako Host Managed SMR, Host Aware SMR pou\u017e\u00edva dva typy z\u00f3n: Konven\u010dn\u00e9 z\u00f3ny na n\u00e1hodn\u00fd z\u00e1pis a Z\u00f3ny preferovan\u00e9 pre sekven\u010dn\u00fd z\u00e1pis (Sequential Write Preferred Zones). Tieto posledn\u00e9, na rozdiel od vy\u0161\u0161ie spomenut\u00fdch z\u00f3n s po\u017eiadavkou na sekven\u010dn\u00fd z\u00e1pis (Sequential Write Required Zones), sa automaticky prev\u00e1dzaj\u00fa na be\u017en\u00e9, ke\u010f za\u010d\u00edna n\u00e1hodn\u00fd z\u00e1pis d\u00e1t.<\/p>\n<p>Implement\u00e1cia SMR s podporou hostite\u013ea predpoklad\u00e1 vn\u00fatorn\u00e9 mechanizmy obnovy po neporad\u00ed z\u00e1pise. Neporiadok d\u00e1ta sa zapisuj\u00fa do vyrovn\u00e1vacej pam\u00e4te, odkia\u013e disk m\u00f4\u017ee pren\u00e1\u0161a\u0165 inform\u00e1cie do z\u00f3ny sekven\u010dn\u00e9ho z\u00e1pisu, ke\u010f s\u00fa z\u00edskan\u00e9 v\u0161etky potrebn\u00e9 bloky. Na riadenie neporiadku z\u00e1pisu a pozadovej defragment\u00e1cie disk pou\u017e\u00edva tabu\u013eku nepriamych odkazov. Av\u0161ak, ak korpor\u00e1tne aplik\u00e1cie vy\u017eaduj\u00fa predv\u00eddate\u013en\u00fd a optimalizovan\u00fd v\u00fdkon, tento cie\u013e je mo\u017en\u00e9 dosiahnu\u0165 iba v pr\u00edpade, \u017ee hostite\u013e preber\u00e1 pln\u00fa kontrolu nad v\u0161etk\u00fdmi pr\u00fadmi d\u00e1t a z\u00f3nami z\u00e1pisu.<br \/>\n<br \/>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/company\/wd\/blog\/524506\/\">habr.com<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u041f\u0435\u0440\u0432\u044b\u0439 \u0432 \u043c\u0438\u0440\u0435 \u0436\u0435\u0441\u0442\u043a\u0438\u0439 \u0434\u0438\u0441\u043a, IBM RAMAC 305, \u0443\u0432\u0438\u0434\u0435\u0432\u0448\u0438\u0439 \u0441\u0432\u0435\u0442 \u0432 1956 \u0433\u043e\u0434\u0443, \u0432\u043c\u0435\u0449\u0430\u043b \u043b\u0438\u0448\u044c 5 \u041c\u0411 \u0434\u0430\u043d\u043d\u044b\u0445, \u0430 \u0432\u0435\u0441\u0438\u043b \u043f\u0440\u0438 \u044d\u0442\u043e\u043c 970 \u043a\u0433 \u0438 \u043f\u043e \u0433\u0430\u0431\u0430\u0440\u0438\u0442\u0430\u043c \u0431\u044b\u043b \u0441\u043e\u043f\u043e\u0441\u0442\u0430\u0432\u0438\u043c \u0441 \u043f\u0440\u043e\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u044b\u043c \u0440\u0435\u0444\u0440\u0438\u0436\u0435\u0440\u0430\u0442\u043e\u0440\u043e\u043c. \u0421\u043e\u0432\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u0435 \u043a\u043e\u0440\u043f\u043e\u0440\u0430\u0442\u0438\u0432\u043d\u044b\u0435 \u0444\u043b\u0430\u0433\u043c\u0430\u043d\u044b \u0441\u043f\u043e\u0441\u043e\u0431\u043d\u044b \u043f\u043e\u0445\u0432\u0430\u0441\u0442\u0430\u0442\u044c\u0441\u044f \u0435\u043c\u043a\u043e\u0441\u0442\u044c\u044e \u0443\u0436\u0435 \u0432 20 \u0422\u0411. \u0422\u043e\u043b\u044c\u043a\u043e \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u044c\u0442\u0435 \u0441\u0435\u0431\u0435: 64 \u0433\u043e\u0434\u0430 \u043d\u0430\u0437\u0430\u0434, \u0434\u043b\u044f \u0442\u043e\u0433\u043e \u0447\u0442\u043e\u0431\u044b \u0437\u0430\u043f\u0438\u0441\u0430\u0442\u044c \u0442\u0430\u043a\u043e\u0435 \u043a\u043e\u043b\u0438\u0447\u0435\u0441\u0442\u0432\u043e \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u0438, [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":97880,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-97879","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u041f\u0435\u0440\u0432\u044b\u0439 \u0432 \u043c\u0438\u0440\u0435 \u0436\u0435\u0441\u0442\u043a\u0438\u0439 \u0434\u0438\u0441\u043a, IBM RAMAC 305.\" \/>\n\t<meta name=\"robots\" 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