Sawubona, Habr! Ngethula ekunakeni kwakho ukuhunyushwa kwalesi sihloko by Andrew Beekhof.
Abantu abaningi bakhetha amaqoqo anamanodi amabili ngoba abonakala elula ngokomqondo futhi ashibhe ngo-33% kunozakwabo abanamanodi amathathu. Nakuba kungenzeka ngempela ukuhlanganisa iqoqo elihle lamanodi amabili, ezimweni eziningi, ngenxa yezimo ezingacatshangelwanga, ukumisa okunjalo kuzodala izinkinga eziningi ezingabonakali.
Isinyathelo sokuqala sokudala noma iyiphi isistimu etholakalayo ephezulu ukuthola nokuzama ukuqeda amaphuzu angawodwana okwehluleka, okuvame ukufushaniswa ngokuthi I-SPoF (iphuzu elilodwa lokwehluleka).
Kuyafaneleka ukukhumbula ukuthi akunakwenzeka ukuqeda zonke izingozi ezingenzeka zesikhathi sokuphumula kunoma yiluphi uhlelo. Lokhu kuvela eqinisweni lokuthi ukuzivikela okujwayelekile ezingozini ukwethulwa kokunye ukunganaki, okuholela ekwandeni kwenkimbinkimbi yesistimu kanye nokuvela kwamaphuzu amasha okuhluleka. Ngakho-ke, ekuqaleni senza ukuvumelana futhi sigxile ezenzakalweni ezihlobene namaphuzu angawodwana okuhluleka, hhayi kumaketanga ezenzakalo ezihlobene futhi, ngakho-ke, izenzakalo ezingenzeka kancane kancane.
Uma kubhekwa ukuhwebelana, asibheki i-SPoF kuphela, kodwa futhi sibhalansisa izingozi nemiphumela, ngenxa yalokho isiphetho salokho okubalulekile nokungabalulekile kungase kwehluke ekusetshenzisweni ngakunye.
Akuwona wonke umuntu odinga abanye abahlinzeki bakagesi abanezintambo zikagesi ezizimele. Nakuba i-paranoia ikhokhele okungenani ikhasimende elilodwa lapho ukuqapha kwabo kuthola i-transformer enephutha. Ikhasimende lishaye izingcingo lizama ukuxwayisa inkampani kagesi kwaze kwaba yilapho kuqhuma i-transformer engalungile.
Isiqalo semvelo siwukuba namanodi angaphezu kweyodwa ohlelweni. Kodwa-ke, ngaphambi kokuba isistimu ihambise izinsiza endaweni esele ngemva kokwehluleka, ngokuvamile idinga ukuqinisekisa ukuthi izinsiza ezihanjiswayo azisebenzi kwenye indawo.
Akukho okuphambene neqoqo elinamanodi amabili uma ukwehluleka kuphumela kuzo zombili izindawo ezinikezela ngewebhusayithi efanayo emile. Kodwa-ke, izinto ziyashintsha uma umphumela uwukuthi zombili izinhlangothi zilawula ngokuzimela ulayini wemisebenzi eyabiwe noma zinikeze ukufinyelela kokubhala okungahlanganisiwe kusizindalwazi esiphindiwe noma isistimu yefayela eyabelwe.
Ngakho-ke, ukuvimbela ukonakala kwedatha ngenxa yokwehluleka kwe-node eyodwa - sithembele kokuthile okubizwa ngokuthi "ukuhlukana" (uthango).
Umgomo wokuhlukanisa
Enhliziyweni yesimiso sokuhlukanisa umbuzo: ingabe i-node yokuncintisana ingabangela ukonakala kwedatha? Esimeni lapho ukonakala kwedatha kuyisimo okungenzeka, isisombululo esihle kungaba ukuhlukanisa i-node kuzo zombili izicelo ezingenayo kanye nesitoreji esiqhubekayo. Indlela ejwayeleke kakhulu yokuhlukanisa iwukunqamula ama-node anephutha.
Kunezigaba ezimbili zezindlela zokuhlukanisa, engizozibiza Qondile и engaqondile, kodwa zingabizwa ngokulinganayo esebenzayo и ukungenzi lutho. Izindlela eziqondile zihlanganisa izenzo ngasohlangothini lontanga abasindile, njengokusebenzelana ne-IPMI (Intelligent Platform Management Interface) noma i-iLO (indlela yokuphatha amaseva uma kungekho ukufinyelela kuwo ngokomzimba), kuyilapho izindlela ezingaqondile zincike kwehlulekile. indawo yokubona ngandlela thize ukuthi isesimweni esingenampilo (noma okungenani ivimbela amanye amalungu ukuthi alulame) kanye nesiginali mayelana nesidingo sokunqamula i-node ehlulekile.
Ikhoramu iyasiza uma usebenzisa izindlela eziqondile nezingaqondile.
Ukuhlukana okuqondile
Esimeni sokuhlukaniswa okuqondile, singasebenzisa ikhoramu ukuvimbela izinhlanga zokuhlukanisa uma kwenzeka inethiwekhi ingaphumeleli.
Ngomqondo wekhoramu, kunolwazi olwanele ohlelweni (ngisho nangaphandle kokuxhuma kontanga yalo) ukuze ama-node azi ngokuzenzakalelayo ukuthi kufanele aqalise ukuhlukana kanye/noma ukululama.
Ngaphandle kwekhoramu, zombili izinhlangothi zokuhlukaniswa kwenethiwekhi zizothatha ngokufanelekile ukuthi olunye uhlangothi lufile futhi luzofuna ukuhlukanisa olunye. Esimeni esibi kakhulu, zombili izinhlangothi ziyakwazi ukuvala iqoqo lonke. Esinye isimo ukufaniswa kokufa, iluphu engapheli yama-node ezalayo, engababoni ontanga yabo, ibaqala kabusha, futhi baqalise ukululama ukuze baqalise kabusha lapho ontanga yabo belandela umqondo ofanayo.
Inkinga ngokuzihlukanisa ukuthi amadivayisi asetshenziswa kakhulu awatholakali ngenxa yezehlakalo zokwehluleka ezifanayo esifuna ukuzikhomba ukuze zilulame. Amakhadi amaningi e-IPMI nawe-iLO afakwe kubasingathi ababalawulayo futhi, ngokuzenzakalelayo, asebenzisa inethiwekhi efanayo, okwenza ababungazi abaqondiwe bakholwe ukuthi abanye abasingathi abaxhumekile ku-inthanethi.
Ngeshwa, izici zokusebenza ze-IPMI kanye namadivayisi we-iLo azivamile ukucatshangelwa ngesikhathi sokuthengwa kwemishini.
Ukuhlukana ngokungaqondile
Ikhoramu nayo ibalulekile ekulawuleni ukuhlukaniswa okungaqondile; uma kwenziwa kahle, ikhoramu ingavumela abasindile ukuthi bacabange ukuthi ama-node alahlekile azoshintshela esimweni esiphephile ngemva kwesikhathi esithile.
Ngalokhu kumisa, isibali sikhathi se-hardware watchdog sisethwa kabusha njalo ngamasekhondi angu-N uma ikhoramu ingalahleki. Uma isibali sikhathi (ngokuvamile iziphindaphinda ezimbalwa zika-N) siphelelwa yisikhathi, idivayisi yenza amandla angalungile ehle (hhayi ukuvala shaqa).
Le ndlela iphumelela kakhulu, kodwa ngaphandle kwekhoramu alukho ulwazi olwanele ngaphakathi kweqoqo lokuyiphatha. Akulula ukuhlukanisa phakathi kokucisha inethiwekhi kanye nokwehluleka kwenodi yontanga. Isizathu salokhu ukuthi ngaphandle kokukwazi ukuhlukanisa phakathi kwamacala amabili, uphoqeleka ukuthi ukhethe ukuziphatha okufanayo kuzo zombili izimo.
Inkinga ngokukhetha imodi eyodwa ukuthi ayikho inkambo yokwenza ekhulisa ukutholakala futhi evimbela ukulahleka kwedatha.
- Uma ukhetha ukucabanga ukuthi inodi yontanga iyasebenza kodwa empeleni yehluleke, iqoqo lizomisa kungenasidingo izinsiza ezizobe zisebenza ukunxephezela ukulahlekelwa kwezinsizakalo ezivela endaweni ehlulekile yontanga.
- Uma uthatha isinqumo sokucabanga ukuthi i-node iphansi, kodwa bekuwukuhluleka kwenethiwekhi futhi empeleni indawo eyirimothi iyasebenza, ngakho-ke kungcono kakhulu ubhalisela ukubuyisana okuzayo okuzayo kwamasethi edatha angumphumela.
Kungakhathaliseki ukuthi usebenzisa yiphi i-heuristic, kuyinto encane ukudala ukwehluleka okuzokwenza ukuthi izinhlangothi zombili zihluleke noma kubangele iqoqo ukuthi livale ama-node asele. Ukungasebenzisi ikhoramu kuncisha ngempela iqoqo elinye lamathuluzi anamandla kunqolobane yalo.
Uma ingekho enye indlela, indlela engcono kakhulu ukudela ubukhona (lapha umbhali ubhekisele kumbono weCAP). Ukutholakala okuphezulu kwedatha eyonakele akusizi muntu, futhi ukuvumelanisa mathupha amasethi edatha ahlukene nakho akujabulisi.
Ikhoramu
Ikhoramu izwakala kahle, akunjalo?
Okubi kuphela ukuthi ukuze ube nayo eqoqweni elinamalungu e-N, udinga ukuba nokuxhumana phakathi kwe-N/2+1 yamanodi akho asele. Okungenzeki kuqoqo lamanodi amabili ngemva kokwehluleka kwenodi eyodwa.
Okugcina kusiletha enkingeni eyisisekelo ngama-node amabili:
Ikhoramu ayiwenzi umqondo kuma-node amaqoqo amabili, futhi ngaphandle kwayo akunakwenzeka ukunquma ngokuthembekile inkambo yesenzo ekhulisa ukutholakala futhi evimbela ukulahleka kwedatha.
Ngisho nasohlelweni lwama-node amabili axhunywe ngekhebula le-crossover, akunakwenzeka ukuhlukanisa ngokucacile phakathi kokuphuma kwenethiwekhi kanye nokwehluleka kwenye i-node. Ukukhubaza isiphetho esisodwa (amathuba okuthi, yiqiniso, alingana nebanga phakathi kwama-node) kuzokwanela ukuvala noma yikuphi ukucabanga ukuthi impilo yesixhumanisi ilingana nempilo ye-node yomlingani.
Ukwenza iqoqo elinamanodi amabili lisebenze
Kwesinye isikhathi iklayenti alikwazi noma alifuni ukuthenga indawo yesithathu, futhi siyaphoqeleka ukuthi sifune enye indlela.
Inketho 1 - Indlela yokuhlukanisa eyimpinda
Idivayisi ye-ILO noma ye-IPMI yenodi imele iphuzu lokwehluleka ngoba, uma ihluleka, abasindile abakwazi ukuyisebenzisa ukuletha indawo esimweni esiphephile. Eqoqweni lamanodi angu-3 noma ngaphezulu, singanciphisa lokhu ngokubala isibalo sekhoramu nokusebenzisa i-hardware watchdog (umshini wokuhlukanisa ngokungaqondile, njengoba kuxoxiwe ngawo ekuqaleni). Esimeni samanodi amabili, kufanele sisebenzise amayunithi wokusabalalisa amandla enethiwekhi (PDUs) esikhundleni salokho.
Ngemva kokwehluleka, osindile uqala azame ukuxhumana nedivayisi eyinhloko yokuhlukanisa (i-iLO eshumekiwe noma i-IPMI). Uma lokhu kuphumelela, ukutakula kuyaqhubeka njengokujwayelekile. Kuphela uma idivayisi ye-ILO/IPMI yehluleka lapho i-PDU ifinyelelwa khona; uma ukufinyelela kuphumelela, ukutakula kungaqhubeka.
Qiniseka ukuthi ubeka i-PDU kunethiwekhi ehlukile kunethrafikhi yeqoqo, ngaphandle kwalokho ukwehluleka okukodwa kwenethiwekhi kuzovimba ukufinyelela kuwo womabili amadivayisi wokuzihlukanisa futhi kuvimbele ukubuyiselwa kwezinsizakalo.
Lapha ungabuza - ingabe i-PDU iyiphuzu elilodwa lokwehluleka? Impendulo iwukuthi, kunjalo.
Uma lobu bungozi bubalulekile kuwe, awuwedwa: xhuma ama-node womabili kuma-PDU amabili bese utshela isofthiwe yokuhlanganisa ukuthi ikusebenzise kokubili lapho unika amandla ama-node kuvulwa futhi avaliwe. Iqoqo manje lihlala lisebenza uma i-PDU eyodwa ifa, futhi ukwehluleka kwesibili kwenye i-PDU noma idivayisi ye-IPMI kuyodingeka ukuze kuvinjwe ukutakula.
Inketho 2 - Ukwengeza i-Arbiter
Kwezinye izimo, ngenkathi indlela yokuhlukanisa eyimpinda ingenzeka ngokobuchwepheshe, inzima ngokwepolitiki. Izinkampani eziningi zithanda ukuba nokwehlukana okuthile phakathi kwabalawuli nabanikazi bezinhlelo zokusebenza, futhi abaphathi benethiwekhi abaqaphela ukuphepha abahlale beshisekela ukwabelana ngezilungiselelo zokufinyelela kwe-PDU nanoma ubani.
Kulesi simo, enye indlela enconyiwe wukudala inkampani yangaphandle engathathi hlangothi engakwazi ukwengeza isibalo sekhoramu.
Uma kwenzeka ukwehluleka, i-node kufanele ikwazi ukubona ama-airwaves entanga yayo noma i-arbiter ukuze ibuyisele izinsizakalo. I-arbiter ihlanganisa nomsebenzi wokunqamula uma ama-node womabili ebona i-arbiter kodwa engakwazi ukubonana.
Le nketho kufanele isetshenziswe ngokuhambisana nendlela yokuhlukanisa engaqondile, njengesibali sikhathi se-hardware watchdog, esilungiselelwa ukubulala umshini uma ulahlekelwa uxhumano kontanga kanye ne-arbiter node. Ngakho-ke, osindile angacabanga ngokunengqondo ukuthi inodi yontanga yakhe izoba sesimweni esivikelekile ngemva kokuphelelwa yisikhathi kwe-hardware watchdog timer.
Umehluko ongokoqobo phakathi kwe-arbiter ne-node yesithathu ukuthi i-arbiter idinga izinsiza ezimbalwa kakhulu ukuze isebenze futhi ingasebenza ngaphezu kweqoqo elilodwa.
Inketho 3 - Isici somuntu
Indlela yokugcina eyokuthi abasindile baqhubeke nokusebenzisa noma yiziphi izinkonzo abebevele bezisebenzisa, kodwa bangaqalisi ezintsha kuze kube yilapho inkinga izixazulula ngokwayo (ukubuyisela inethiwekhi, ukuqalisa kabusha i-node) noma umuntu azibophezele ekuqinisekiseni mathupha ukuthi olunye uhlangothi lufile.
Inketho yebhonasi
Ingabe ngishilo ukuthi ungakwazi ukwengeza inodi yesithathu?
Ama-racks amabili
Ngenxa yokuphikisana, ake senze sengathi ngikuqinisekisile ngokufaneleka kwe-node yesithathu, manje kufanele sicabangele ukuhlelwa ngokomzimba kwama-node. Uma zihlaliswe (futhi zinikwa amandla) endaweni yokubeka efanayo, lokhu kuphinde kwakha i-SPoF, kanye nengenakuxazululwa ngokungeza i-rack yesibili.
Uma lokhu kumangalisa, cabanga ukuthi yini engenzeka uma i-rack enama-node amabili ihluleka, nokuthi i-node esaphila ingahlukanisa kanjani phakathi kwalokho nokwehluleka kwenethiwekhi.
Impendulo emfushane ukuthi akunakwenzeka, futhi futhi sibhekene nazo zonke izinkinga esimweni se-node ezimbili. Noma osindile:
- indiva ikhoramu futhi izame ngokungalungile ukuqalisa ukubuyisela ngesikhathi sokuphela kwenethiwekhi (ikhono lokuqeda ukuhlukaniswa yindaba ehlukile futhi kuncike ekutheni i-PDU iyabandakanyeka yini nokuthi babelana ngamandla nanoma yimaphi ama-rack), noma
- ihlonipha ikhoramu futhi izinqamule ngaphambi kwesikhathi lapho inodi yontanga yehluleka
Kunoma yikuphi, ama-rack amabili awekho kangcono kuneyodwa, futhi ama-node kufanele athole amandla azimele noma asatshalaliswe kokuthathu (noma ngaphezulu, kuye ngokuthi mangaki ama-node) ama-racks.
Izikhungo ezimbili zedatha
Kuleli qophelo, abafundi abangasenandaba nengozi bangase bafune ukucabangela ukutakula kwenhlekelele. Kwenzekani lapho i-asteroid ishaya isikhungo sedatha esifanayo namanodi ethu amathathu asabalale kuma-rack amathathu ahlukene? Ngokusobala Izinto Ezimbi, kodwa kuye ngezidingo zakho, ukwengeza isikhungo sedatha sesibili kungase kunganele.
Uma kwenziwa kahle, isikhungo sedatha sesibili sikunikeza (futhi ngokunengqondo kanjalo) ikhophi yakamuva nengaguquguquki yamasevisi akho kanye nedatha yawo. Kodwa-ke, njengakuma-node amabili, izimo ze-rack ezimbili, alukho ulwazi olwanele ohlelweni lokuqinisekisa ukutholakala okuphezulu nokuvimbela inkohlakalo (noma ukungafani kwesethi yedatha). Ngisho nama-node amathathu (noma ama-rack), ukuwasakaza ezikhungweni zedatha ezimbili kuphela kushiya isistimu ingakwazi ukwenza isinqumo esifanele uma kwenzeka kuba nomcimbi (osemathubeni amaningi kakhulu) lapho bobabili abathintekayo bengakwazi ukuxhumana.
Lokhu akusho ukuthi isixazululo sesikhungo sedatha esikabili asifanele neze. Izinkampani ngokuvamile zifuna ukuthi umuntu aqaphele ngaphambi kokuthatha isinyathelo esingavamile sokuthuthela esikhungweni sedatha eyisipele. Vele ukhumbule ukuthi uma ufuna ukucisha ngokuzenzakalelayo, uzodinga isikhungo sedatha sesithathu ukuze ikhoramu ibe nengqondo (kungaba ngokuqondile noma ngomxazululi), noma uzothola indlela yokuvala yonke imininingwane ngokuthembekile. isikhungo.
Source: www.habr.com