Theorem ya CAP ndiye mwala wapangodya wa chiphunzitso chogawa. Zoonadi, mkangano wozungulira izo sikutha: matanthauzo ake sali ovomerezeka, ndipo palibe umboni weniweni ...
Chinthu chokha chomwe sichidziwika bwino ndi tanthauzo la chilembo "P". Gulu likagawika, limasankha kuti lisayankhe mpaka chiwerengero cha anthu chikwaniritsidwe, kapena kubweza deta yomwe ilipo. Kutengera zotsatira za chisankhochi, dongosololi limagawidwa ngati CP kapena AP. Cassandra, mwachitsanzo, akhoza kuchita mwanjira iliyonse, kutengera ngakhale zoikamo zamagulu, koma pazigawo za pempho lililonse. Koma ngati dongosolo si "P" ndipo anagawanika, ndiye chiyani?
Yankho la funsoli ndilosayembekezereka: gulu la CA silingagawike.
Ndi masango amtundu wanji amene sangathe kugawanika?
Chofunikira kwambiri chamagulu oterowo ndi njira yogawana deta yogawana. Nthawi zambiri, izi zikutanthauza kulumikizana ndi SAN, zomwe zimalepheretsa kugwiritsa ntchito njira za CA kumabizinesi akuluakulu omwe amatha kukonza zomangamanga za SAN. Kuti ma seva angapo agwire ntchito ndi deta yomweyi, makina ophatikizika amafayilo amafunikira. Machitidwe amafayilo otere akupezeka mu HPE (CFS), Veritas (VxCFS) ndi IBM (GPFS).
Oracle RAC
Njira ya Real Application Cluster idawonekera koyamba mu 2001 ndikutulutsidwa kwa Oracle 9i. M'magulu otere, ma seva angapo amagwira ntchito ndi database yomweyo.
Oracle imatha kugwira ntchito ndi mafayilo onse ophatikizika komanso yankho lake - ASM, Automatic Storage Management.
Kope lililonse limasunga zolemba zake. Ntchitoyi ikuchitika ndikuchitidwa ndi chochitika chimodzi. Ngati chochitika sichikanika, imodzi mwamagulu omwe atsala (mwachitsanzo) amawerenga chipika chake ndikubwezeretsa zomwe zidatayika - potero zimatsimikizira kupezeka.
Zochitika zonse zimasunga cache yawo, ndipo masamba omwewo (ma block) amatha kukhala m'malo angapo nthawi imodzi. Komanso, ngati nthawi ina ikufunika tsamba ndipo ili mu cache ya nthawi ina, ikhoza kulitenga kwa mnansi wake pogwiritsa ntchito makina osungiramo cache m'malo mowerenga kuchokera pa disk.
Koma chimachitika ndi chiyani ngati imodzi mwazochitikazo ikufunika kusintha deta?
Chodabwitsa cha Oracle ndikuti ilibe ntchito yotseka yodzipatulira: ngati seva ikufuna kutseka mzere, ndiye kuti cholembera chotsekera chimayikidwa mwachindunji patsamba lokumbukira pomwe mzere wokhoma uli. Chifukwa cha njirayi, Oracle ndiye wopambana pamasewera a monolithic: ntchito yotseka sikhala vuto. Koma pamasinthidwe amagulu, kamangidwe kotereku kumatha kubweretsa kuchuluka kwa magalimoto pamaneti ndi kutsekeka.
Rekodi ikatsekedwa, chochitika chimadziwitsa zochitika zina zonse kuti tsamba lomwe limasunga rekodiyo limakhala lokhazikika. Ngati chochitika china chikufunika kusintha zolemba patsamba lomwelo, ziyenera kudikirira mpaka zosintha zapatsamba zichitike, ndiye kuti, chidziwitso chosintha chimalembedwa ku nyuzipepala pa disk (ndipo ntchitoyo ingapitirire). Zitha kuchitikanso kuti tsamba lidzasinthidwe motsatizana ndi makope angapo, ndiyeno polemba tsambalo ku diski muyenera kudziwa yemwe amasunga tsamba lino.
Kusintha mwachisawawa masamba omwewo m'malo osiyanasiyana a RAC kumapangitsa kuti magwiridwe antchito a database atsike kwambiri, mpaka pomwe magwiridwe antchito amagulu amatha kukhala otsika kuposa nthawi imodzi.
Kugwiritsa ntchito bwino kwa Oracle RAC ndikugawanitsa deta (mwachitsanzo, pogwiritsa ntchito makina ogawa magawo) ndikupeza magawo aliwonse kudzera mu node yodzipatulira. Cholinga chachikulu cha RAC sichinali kukweza kopingasa, koma kuonetsetsa kulolerana kwa zolakwika.
Ngati node imasiya kuyankha kugunda kwa mtima, ndiye kuti mfundo yomwe idayizindikira imayamba njira yovota pa diski. Ngati mfundo yosowayo sinadziwike apa, ndiye kuti imodzi mwa mfundozo imakhala ndi udindo wobwezeretsa deta:
- "amaundana" masamba onse omwe anali mu cache ya node yosowa;
- amawerenga zipika (kubwereza) za node yosowa ndikubwerezanso zosintha zomwe zalembedwa muzolembazi, ndikuwunikanso ngati ma node ena ali ndi masamba aposachedwa amasamba omwe asinthidwa;
- amabwerera mmbuyo podikirira zochita.
Kuti muchepetse kusinthana pakati pa ma node, Oracle ili ndi lingaliro la ntchito - chitsanzo chenicheni. Chitsanzo chingathe kupereka mautumiki angapo, ndipo ntchito imatha kuyenda pakati pa ma node. Chochitika chogwiritsa ntchito gawo lina la nkhokwe (mwachitsanzo, gulu lamakasitomala) limagwira ntchito ndi ntchito imodzi, ndipo ntchito yomwe imayang'anira gawo ili la database imasunthira kumalo ena pomwe node ikulephera.
IBM Pure Data Systems for Transactions
Njira yothetsera masango ya DBMS idawonekera mu mbiri ya Blue Giant mu 2009. Mwachidziwitso, ndiye wolowa m'malo mwa gulu la Parallel Sysplex, lomangidwa pazida "zokhazikika". Mu 2009, DB2 pureScale inatulutsidwa ngati pulogalamu ya pulogalamu, ndipo mu 2012, IBM inapereka chipangizo chotchedwa Pure Data Systems for Transactions. Siziyenera kusokonezedwa ndi Pure Data Systems for Analytics, zomwe sizili kanthu koma kutchedwa Netezza.
Poyang'ana koyamba, zomangamanga za pureScale ndizofanana ndi Oracle RAC: momwemonso, mfundo zingapo zimagwirizanitsidwa ndi dongosolo losungiramo deta, ndipo node iliyonse imayendetsa chitsanzo chake cha DBMS ndi malo ake okumbukira ndi zipika zamalonda. Koma, mosiyana ndi Oracle, DB2 ili ndi ntchito yotseka yodzipatulira yoimiridwa ndi njira za db2LLM *. Pokonzekera masango, ntchitoyi imayikidwa pamfundo yosiyana, yomwe imatchedwa coupling center (CF) mu Parallel Sysplex, ndi PowerHA mu Pure Data.
PowerHA imapereka ntchito zotsatirazi:
- woyang'anira loko;
- chosungira chapadziko lonse lapansi;
- gawo la interprocess communications.
Kusamutsa deta kuchokera ku PowerHA kupita kumalo osungirako zinthu zakale ndi kumbuyo, kukumbukira kwakutali kumagwiritsidwa ntchito, kotero kuti mgwirizano wamagulu uyenera kuthandizira protocol ya RDMA. PureScale imatha kugwiritsa ntchito Infiniband ndi RDMA pa Ethernet.
Ngati node ikufunika tsamba, ndipo tsamba ili siliri mu cache, ndiye kuti node imapempha tsambalo mu cache yapadziko lonse, ndipo pokhapokha ngati palibe, amawerenga kuchokera ku disk. Mosiyana ndi Oracle, pempholi limapita ku PowerHA kokha, osati kumalo oyandikana nawo.
Ngati chochitika chikusintha mzere, chimatseka munjira yokhayokha, ndi tsamba lomwe mzerewo uli munjira yogawana. Maloko onse amalembedwa mu Global Lock Manager. Ntchitoyo ikatha, node imatumiza uthenga kwa woyang'anira loko, yemwe amakopera tsamba losinthidwa ku cache yapadziko lonse lapansi, amamasula zotsekera, ndikulepheretsa tsamba losinthidwa m'ma cache a node zina.
Ngati tsamba lomwe mzere wosinthidwa udatsekedwa kale, ndiye kuti woyang'anira loko adzawerenga tsamba losinthidwa kuchokera kukumbukira node yomwe idasintha, kumasula loko, kulepheretsa tsamba losinthidwa m'ma cache a node zina, ndipo perekani loko tsambalo ku mfundo yomwe yapempha.
"Zodetsedwa", ndiye kuti, zasinthidwa, masamba amatha kulembedwa ku disk kuchokera kumalo okhazikika komanso kuchokera ku PowerHA (castout).
Ngati imodzi mwa node ya pureScale ikulephera, kuchira kumangokhala ndi zochitika zokha zomwe zinali zisanakwaniritsidwe panthawi ya kulephera: masamba osinthidwa ndi mfundoyo muzochita zomaliza ali mu cache yapadziko lonse pa PowerHA. Node imayambiranso mwakusintha pang'onopang'ono pa imodzi mwama seva omwe ali mgululi, imabwerera mmbuyo ndikudikirira zochitika ndikutulutsa zotsekera.
PowerHA imayenda pa ma seva awiri ndipo node ya master imatengera dziko lake mogwirizana. Ngati node yayikulu ya PowerHA ikulephera, gululi likupitilizabe kugwira ntchito ndi node yosunga zobwezeretsera.
Zoonadi, ngati mutapeza deta yokhazikitsidwa kudzera mu node imodzi, ntchito yonse ya gululo idzakhala yapamwamba. PureScale imatha kuzindikira kuti dera linalake la data likukonzedwa ndi mfundo imodzi, ndiyeno maloko onse okhudzana ndi deralo adzasinthidwa kwanuko ndi mfundo popanda kulumikizana ndi PowerHA. Koma pulogalamuyo ikangoyesa kupeza izi kudzera mu node ina, kukonzanso kwa loko kumayambiranso.
Mayeso amkati a IBM pa ntchito yowerengera 90% ndikulemba 10%, yomwe ili yofanana kwambiri ndi ntchito zopanga zenizeni padziko lonse lapansi, ikuwonetsa pafupifupi mzere wokulira mpaka 128 node. Zoyeserera, mwatsoka, sizinaululidwe.
HPE NonStop SQL
Mbiri ya Hewlett-Packard Enterprise ilinso ndi nsanja yake yomwe ilipo. Iyi ndiye nsanja ya NonStop, yomwe idatulutsidwa pamsika mu 1976 ndi Tandem Computers. Mu 1997, kampaniyo idagulidwa ndi Compaq, yomwe idaphatikizidwa ndi Hewlett-Packard mu 2002.
NonStop imagwiritsidwa ntchito popanga mapulogalamu ovuta - mwachitsanzo, HLR kapena kukonza makadi aku banki. Pulatifomu imaperekedwa mwa mawonekedwe a mapulogalamu ndi hardware complex (chogwiritsira ntchito), chomwe chimaphatikizapo ma node a makompyuta, njira yosungiramo deta ndi zipangizo zoyankhulirana. Netiweki ya ServerNet (m'machitidwe amakono - Infiniband) imagwira ntchito zonse zosinthana pakati pa node ndi mwayi wopeza njira yosungira deta.
Mabaibulo oyambirira a dongosolo anagwiritsa ntchito mapurosesa eni amene analunzanitsidwa wina ndi mzake: ntchito zonse anachita synchronously ndi mapurosesa angapo, ndipo mwamsanga pamene mmodzi wa mapurosesa analakwitsa, izo zinazimitsidwa, ndipo chachiwiri anapitiriza ntchito. Pambuyo pake, makinawo adasinthira ku mapurosesa wamba (yoyamba MIPS, kenako Itanium ndipo pomaliza x86), ndipo njira zina zidayamba kugwiritsidwa ntchito polumikizana:
- mauthenga: ndondomeko iliyonse ya dongosolo imakhala ndi "mthunzi" mapasa, omwe ndondomeko yogwira ntchito nthawi ndi nthawi imatumiza mauthenga okhudza momwe alili; ngati njira yaikulu ikulephera, ndondomeko ya mthunzi imayamba kugwira ntchito kuyambira nthawi yomwe uthenga womaliza umatsimikiziridwa;
- kuvota: makina osungira ali ndi gawo lapadera la hardware lomwe limavomereza maulendo angapo ofanana ndikuwachita pokhapokha ngati zopezekazo zikufanana; M'malo molumikizana ndi thupi, mapurosesa amagwira ntchito mosagwirizana, ndipo zotsatira za ntchito yawo zimafaniziridwa pa mphindi za I / O zokha.
Kuyambira 1987, DBMS yolumikizana yakhala ikugwira ntchito pa NonStop nsanja - yoyamba SQL/MP, kenako SQL/MX.
Dongosolo lonse la database lagawidwa magawo, ndipo gawo lililonse limayang'anira njira yakeyake ya Data Access Manager (DAM). Imapereka njira zojambulira, kusungitsa, ndi kutseka. Kukonza kwa data kumachitidwa ndi Executor Server Processes yomwe ikuyenda pamanodi omwewo monga oyang'anira data omwe amafanana. SQL/MX scheduler imagawa ntchito pakati pa ochita ndikuphatikiza zotsatira. Pakafunika kusintha kogwirizana, ndondomeko ya magawo awiri yoperekedwa ndi laibulale ya TMF (Transaction Management Facility) imagwiritsidwa ntchito.
NonStop SQL ikhoza kuyika patsogolo njira kuti mafunso atalikirapo asasokoneze ntchito. Komabe, cholinga chake ndikukonza zochitika zazifupi, osati kusanthula. Wopanga mapulogalamu amatsimikizira kupezeka kwa gulu la NonStop pamlingo wa "zisanu", ndiye kuti, nthawi yopuma ndi mphindi 5 zokha pachaka.
SAP-HANA
Kutulutsidwa koyamba kokhazikika kwa HANA DBMS (1.0) kunachitika mu Novembala 2010, ndipo phukusi la SAP ERP linasinthira ku HANA mu Meyi 2013. Pulatifomuyi imachokera ku matekinoloje ogulidwa: TREX Search Engine (sakani mu yosungirako columnar), P * TIME DBMS ndi MAX DB.
Liwu loti "HANA" palokha ndi chidule, High performance ANAlytical Appliance. DBMS iyi imaperekedwa mumtundu wa code yomwe imatha kuthamanga pa ma seva aliwonse a x86, komabe, kukhazikitsa kwa mafakitale kumaloledwa pazida zovomerezeka. Mayankho akupezeka kuchokera ku HP, Lenovo, Cisco, Dell, Fujitsu, Hitachi, NEC. Zosintha zina za Lenovo zimalola kugwira ntchito popanda SAN - gawo la makina osungira wamba limaseweredwa ndi gulu la GPFS pama diski akomweko.
Mosiyana ndi nsanja zomwe zatchulidwa pamwambapa, HANA ndi DBMS yokumbukira, mwachitsanzo, chithunzi chachikulu cha data chimasungidwa mu RAM, ndipo zolemba zokha ndi zojambulidwa nthawi ndi nthawi zimalembedwa ku disk kuti zibwezeretsedwe pakagwa tsoka.
Node iliyonse yamagulu a HANA imayang'anira gawo lake la data, ndipo mapu amasungidwa mu gawo lapadera - Name Server, yomwe ili pa node yogwirizanitsa. Deta sinabwerezedwe pakati pa mfundo. Zambiri zotsekera zimasungidwanso pa node iliyonse, koma makinawa ali ndi chowunikira padziko lonse lapansi.
Wothandizira wa HANA akalumikizana ndi gulu, amatsitsa topology yake ndipo amatha kupeza node iliyonse mwachindunji, kutengera zomwe akufuna. Ngati kugulitsako kumakhudza chidziwitso cha node imodzi, ndiye kuti kutha kuchitidwa kwanuko ndi mfundoyo, koma ngati deta ya node ingapo ikusintha, node yoyambira imalumikizana ndi mfundo yogwirizanitsa, yomwe imatsegula ndikugwirizanitsa ntchito yogawidwa, ndikuyigwiritsa ntchito. optimized two phase commit protocol.
Node yogwirizanitsa imabwerezedwa, kotero ngati wogwirizanitsa alephera, node yosungira nthawi yomweyo imatenga. Koma ngati node yokhala ndi deta ikulephera, ndiye njira yokhayo yopezera deta yake ndikuyambitsanso node. Monga lamulo, magulu a HANA amasunga seva yopuma kuti ayambitsenso node yotayika pa iyo mwamsanga.
Source: www.habr.com