Iyo CAP theorem ndiyo ibwe rekona reakagoverwa masisitimu theory. Zvechokwadi, gakava rakaripoteredza hariperi: tsananguro dzirimo hadzisi dzechokwadi, uye hapana humbowo hwakasimba ... Zvakadaro, takamira zvakasimba pazvinzvimbo zvemazuva ese common sense™, isu tinonzwisisa kuti theorem ndeyechokwadi.
Chinhu chimwe chete chisiri pachena ndicho chirevo chetsamba "P". Kana boka racho rikakamurwa, rinosarudza kusapindura kusvika quorum yasvika, kana kudzosera data iripo. Zvichienderana nemhedzisiro yesarudzo iyi, sisitimu inoiswa senge CP kana AP. Cassandra, semuenzaniso, anogona kuzvibata chero nzira, zvichienderana kwete kunyangwe pazvirongwa zvemasumbu, asi pamaparamita echikumbiro chega chega. Asi kana iyo system isiri "P" uye inotsemuka, zvino chii?
Mhinduro kumubvunzo uyu neimwe nzira isingatarisirwe: a CA cluster haigone kupatsanura.
Iri isumbu rudzii risingagoni kupatsanurana?
Hunhu hunokosha hweboka rakadaro ndeyekugovaniswa kwekuchengetedza data system. Muzviitiko zvakawanda, izvi zvinoreva kubatanidza pamusoro peSAN, iyo inoderedza kushandiswa kweCA mhinduro kumabhizinesi makuru anokwanisa kuchengetedza SAN infrastructure. Kuti maseva akawanda ashande neiyo data, a clustered file system inodiwa. Mafaira akadaro anowanikwa muHPE (CFS), Veritas (VxCFS) uye IBM (GPFS) portfolios.
Oracle RAC
Iyo Real Application Cluster sarudzo yakatanga kuoneka muna 2001 nekuburitswa kweOracle 9i. Musumbu rakadaro, akati wandei sevha mameseji anoshanda neiyo imwechete database.
Oracle inogona kushanda nezvose zvakasanganiswa faira system uye mhinduro yayo - ASM, Automatic Storage Management.
Kopi imwe neimwe inochengeta chinyorwa chayo. Iko kutengeserana kunoitwa uye kunoitwa nechiitiko chimwe. Kana chiitiko chikatadza, imwe yeasara cluster node (zviitiko) inoverenga irogi rayo uye inodzoreredza iyo yakarasika data - nekudaro kuve nechokwadi kuwanikwa.
Mamiriro ese anochengetedza cache yavo, uye iwo mapeji mamwechete (mabhuraki) anogona kunge ari mune cache yezviitiko zvakawanda panguva imwe chete. Uyezve, kana imwe muenzaniso ichida peji uye iri mune cache yeimwe muenzaniso, inogona kuiwana kubva kumuvakidzani wayo ichishandisa cache fusion mechanism pane kuverenga kubva kudiski.
Asi chii chinoitika kana imwe yezviitiko ichida kuchinja data?
Iyo peculiarity yeOracle ndeyokuti haina yakatsaurirwa yekuvhara sevhisi: kana sevha ichida kukiya mutsara, ipapo rekodhi rekodhi rinoiswa zvakananga pane peji rekurangarira uko mutsara wakakiiwa uripo. Nekuda kwemaitiro aya, Oracle ndiye mukwikwidzi wekuita pakati pemonolithic dhatabhesi: iyo yekuvhara sevhisi haimbove bhodhoro. Asi mukugadziriswa kwechikwata, chivakwa chakadaro chinogona kutungamira kune yakanyanya network traffic uye deadlocks.
Kana rekodhi ravharwa, chiitiko chinozivisa zvimwe zvese kuti peji inochengeta iyo rekodhi ine yakasarudzika. Kana imwe chiitiko ichida kushandura rekodhi pane imwechete peji, inofanirwa kumirira kusvikira shanduko yepeji ichiitwa, ndiko kuti, shanduko yeruzivo inonyorerwa kune jenari pa diski (uye kutengeserana kunogona kuenderera). Zvinogonawo kuitika kuti peji ichashandurwa zvakateedzana nemakopi akati wandei, uye kana uchinyora peji kune dhisiki iwe uchafanirwa kuziva kuti ndiani anochengeta yazvino vhezheni yepeji ino.
Kugara uchivandudza mapeji mamwe chete munzvimbo dzakasiyana dzeRAC node kunoita kuti dhizaini idonhe zvakanyanya, kusvika padanho rekuti cluster performance inogona kudzikira pane iyo yechiitiko chimwe chete.
Iko kushandiswa chaiko kweOracle RAC ndeyekugovanisa data data (semuenzaniso, kushandisa yakakamurwa tafura meshini) uye kuwana yega yega seti yezvikamu kuburikidza nenode yakatsaurirwa. Chinangwa chikuru cheRAC chaive chisiri kuyera kuyera, asi kuve nechokwadi chekushivirira kukanganisa.
Kana node ikamira kupindura kurova kwemoyo, ipapo node yakazviona inotanga kutanga nzira yekuvhota pa diski. Kana iyo node isipo isina kucherechedzwa pano, ipapo imwe yemanodhi inotora mutoro wekudzoreredza data:
- "inoomesa" mapeji ese aive mu cache yeinodhi isipo;
- inoverenga matanda (redo) yeinodhi yakashaikwa uye inoshandisazve shanduko dzakanyorwa mumatanda aya, panguva imwe chete ichitarisa kana dzimwe node dziine mamwe mavhezheni achangoburwa emapeji ari kuchinjwa;
- inodzokera kumashure yakamirira matransaction.
Kurerutsa kuchinja pakati pemanodhi, Oracle ine pfungwa yebasa - muenzaniso chaiwo. Muenzaniso unogona kushandira akawanda masevhisi, uye sevhisi inogona kufamba pakati pemanodhi. Chiitiko chekushandisa chinoshanda chimwe chikamu chedhatabhesi (semuenzaniso, boka revatengi) rinoshanda nesevhisi imwe, uye sevhisi ine chekuita nechikamu ichi chedhatabhesi inoenda kune imwe node kana node yatadza.
IBM Pure Data Systems yeTransactions
A cluster solution yeDBMS yakaonekwa muBlue Giant portfolio muna 2009. Ideologically, ndiye mutsivi weParallel Sysplex cluster, yakavakirwa pamidziyo "yenguva dzose". Muna 2009, DB2 pureScale yakaburitswa sesoftware suite, uye muna 2012, IBM yakapa mudziyo unonzi Pure Data Systems for Transactions. Izvo hazvifanirwe kuvhiringika nePure Data Systems yeAnalytics, iyo isiri chinhu kunze kwekutumidzwa zita rekuti Netezza.
Pakutanga kuona, iyo pureScale architecture yakafanana neOracle RAC: nenzira imwecheteyo, node dzinoverengeka dzakabatana kune yakajairwa data yekuchengetedza sisitimu, uye imwe neimwe node inomhanyisa yayo DBMS muenzaniso nenzvimbo dzayo dzekurangarira uye matanda ekutengesa. Asi, kusiyana neOracle, DB2 ine yakatsaurwa yekuvhara sevhisi inomiririrwa neseti ye db2LLM * maitiro. Mukugadziriswa kwemasumbu, sevhisi iyi inoiswa pane imwe node, iyo inonzi coupling nzvimbo (CF) muParallel Sysplex, uye PowerHA muPure Data.
PowerHA inopa masevhisi anotevera:
- lock manager;
- global buffer cache;
- nzvimbo ye interprocess communications.
Kuendesa data kubva kuPowerHA kuenda kune dhatabhesi node uye kumashure, kure kure memory yekupinda inoshandiswa, saka iyo cluster yekubatanidza inofanirwa kutsigira RDMA protocol. PureScale inogona kushandisa ese Infiniband uye RDMA pamusoro peEthernet.
Kana node inoda peji, uye peji iyi haisi mu cache, ipapo node inokumbira peji mucheji yepasi rose, uye chete kana isipo, inoiverenga kubva ku diski. Kusiyana neOracle, chikumbiro chinoenda chete kuPowerHA, uye kwete kune dzakavakidzana node.
Kana muenzaniso uchizochinja mutsara, unoikiya mune yakasarudzika modhi, uye peji iyo mutsara unowanikwa mune yakagovaniswa modhi. Makiyi ese akanyoreswa mune yepasi rose yekuvhara maneja. Kana kutengeserana kwapera, node inotumira meseji kumaneja wekiyi, iyo inokopa iyo yakagadziridzwa peji kune yepasirese cache, inoburitsa makiyi, uye inokanganisa iyo yakagadziridzwa peji mune cache yemamwe ma node.
Kana iyo peji ine mutsara wakagadziridzwa watokiyiwa, ipapo maneja wekiyi anoverenga peji yakagadziridzwa kubva mundangariro yenode yakaita shanduko, kusunungura kukiya, kuita kuti peji yakagadziridzwa isashande mune cache dzedzimwe node, uye ipa peji rekukiya kune node yarikumbira.
"Yakasviba", ndiko kuti, yakashandurwa, mapeji anogona kunyorwa ku diski kubva kune imwe nguva node uye kubva kuPowerHA (castout).
Kana imwe yepureScale node ikakundikana, kudzoreredza kunongogumira kune izvo chete kutengeserana kwanga kusati kwapedzwa panguva yekutadza: mapeji akagadziridzwa neiyo node mukuita kwakapedzwa kuri mu cache yepasi rose paPowerHA. Iyo node inotangazve mune yakaderedzwa gadziriso pane imwe yemaseva ari musumbu, inodzokera kumashure yakamirira kutengeserana uye inoburitsa makiyi.
PowerHA inomhanya pamaseva maviri uye iyo master node inodzokorora mamiriro ayo synchronously. Kana iyo yekutanga PowerHA node ikatadza, cluster inoramba ichishanda neiyo backup node.
Ehe, kana iwe ukawana iyo data yakaiswa kuburikidza nenode imwe chete, kuita kwese kwechikwata kuchave kwakakwira. PureScale inogona kutoona kuti imwe nzvimbo yedata iri kugadziriswa nenode imwe, uyezve makiyi ane chekuita nenzvimbo iyoyo anozogadziriswa munharaunda nenode pasina kutaurirana nePowerHA. Asi kana application ikangoyedza kuwana iyi data kuburikidza neimwe node, centralized lock processing inotangazve.
Miedzo yemukati yeIBM pahuwandu hwebasa re90% kuverenga uye 10% nyora, iyo yakafanana neiyo-yepasirese yekugadzira mitoro yemabasa, inoratidza inenge mutsara kuyera kusvika ku128 node. Mamiriro ekuedzwa, zvinosuruvarisa, haana kuburitswa.
HPE NonStop SQL
Iyo Hewlett-Packard Enterprise portfolio inewo yayo inowanikwa zvakanyanya. Iyi ipuratifomu yeNonStop, yakaburitswa kumusika muna 1976 neTandem Computers. Muna 1997, kambani yakawanikwa neCompaq, iyo yakazobatanidzwa neHewlett-Packard mu2002.
NonStop inoshandiswa kugadzira zvakakosha - semuenzaniso, HLR kana kadhi rebhangi kugadzirisa. Ipuratifomu inounzwa muchimiro chesoftware uye hardware yakaoma (mudziyo), iyo inosanganisira komputa node, dhizaini yekuchengetedza data uye midziyo yekutaurirana. Iyo ServerNet network (mune azvino masisitimu - Infiniband) inoshandira zvese zvekutsinhana pakati penodhi uye yekuwana iyo data yekuchengetedza system.
Mavhezheni ekutanga ehurongwa akashandisa proprietary processors ayo akawiriraniswa kune mumwe nemumwe: zvese mashandiro akaitwa synchronously nevakawanda processors, uye pakangoita imwe processor kukanganisa, yakadzimwa, uye yechipiri yakaramba ichishanda. Gare gare sisitimu yakachinjirwa kune yakajairwa processors (yekutanga MIPS, yozotevera Itanium uye pakupedzisira x86), uye dzimwe nzira dzakatanga kushandiswa kuwiriranisa:
- mameseji: yega yega system process ine "mumvuri" mapatya, iyo iyo inoshanda maitiro nguva nenguva inotumira meseji nezve chimiro chayo; kana iyo huru hurongwa ikakundikana, iyo mumvuri maitiro anotanga kushanda kubva panguva yakatemwa neshoko rekupedzisira;
- kuvhota: sisitimu yekuchengetera ine yakakosha hardware chikamu inogamuchira akawanda akafanana mapindiro uye inoaita chete kana iyo yekuwana ichienderana; Panzvimbo yekuwiriranisa kwemuviri, ma processor anoshanda asynchronously, uye mhedzisiro yebasa ravo inofananidzwa chete panguva dzeI / O.
Kubva 1987, DBMS yehukama yanga ichimhanya paNonStop papuratifomu - yekutanga SQL/MP, uye gare gare SQL/MX.
Iyo yese dhatabhesi yakakamurwa kuita zvikamu, uye chikamu chimwe nechimwe chine mutoro kune chayo cheData Access Manager (DAM) maitiro. Inopa data kurekodha, caching, uye kukiya nzira. Kugadziriswa kwedata kunoitwa neExecutor Server Maitiro anomhanya pane imwechete node seanoenderana mamaneja edata. Iyo SQL/MX scheduler inokamura mabasa pakati pevaiti uye inounganidza mhedzisiro. Pazvinenge zvichidikanwa kuita shanduko dzakabvumiranwa, iyo yezvikamu zviviri-yekuita protocol inopihwa neTMF (Transaction Management Facility) raibhurari inoshandiswa.
NonStop SQL inogona kukoshesa maitiro kuitira kuti mibvunzo yakareba yekuongorora isakanganise nekuita kwekutengeserana. Nekudaro, chinangwa chayo ndechekugadzirisa mapfupi ekutengeserana, uye kwete analytics. Mugadziri anovimbisa kuwanikwa kweNonStop cluster pamwero we "mapfumbamwe", kureva kuti, nguva yekuzorora imaminitsi mashanu chete pagore.
SAP-HANA
Kuburitswa kwekutanga kwakagadzikana kweHANA DBMS (1.0) kwakaitika muna Mbudzi 2010, uye SAP ERP package yakachinjirwa kuHANA muna Chivabvu 2013. Iyi puratifomu yakavakirwa pamatekinoroji akatengwa: TREX Injini Yekutsvagisa (tsvaga mune columnar kuchengetedza), P * TIME DBMS uye MAX DB.
Izwi rekuti "HANA" pacharo ichidimbu, High performance Analytical Appliance. Iyi DBMS inopihwa muchimiro chekodhi inogona kumhanya pane chero x86 maseva, zvisinei, kuiswa kwemaindasitiri kunobvumidzwa chete pamidziyo yakasimbiswa. Mhinduro dziripo kubva kuHP, Lenovo, Cisco, Dell, Fujitsu, Hitachi, NEC. Mamwe magadzirirwo eLenovo anotobvumira kushanda pasina SAN - iro basa reyakajairwa kuchengetedza system inotambwa neGPFS cluster pamadhisiki emunharaunda.
Kusiyana nemapuratifomu akanyorwa pamusoro apa, HANA iri mu-memory DBMS, i.e. iyo yekutanga data data inochengetwa mu RAM, uye chete matanda uye periodic snapshots inonyorerwa dhisiki yekupora kana njodzi.
Imwe neimwe HANA cluster node ine chekuita nechikamu chayo che data, uye mepu yedata inochengetwa mune yakakosha chikamu - Zita Server, iri pane coordinator node. Data haina kudhindwa pakati pemanodhi. Ruzivo rwekuvhara runochengetwawo pane imwe neimwe node, asi iyo system ine global deadlock detector.
Kana mutengi weHANA akabatana nesumbu, inodhawunirodha topology yayo uye inokwanisa kuwana chero node zvakananga, zvichienderana nekuti inoda data ipi. Kana kutengeserana kuchikanganisa data yenode imwe chete, zvino inogona kuitwa munharaunda neiyo node, asi kana data yenzvimbo dzakawanda ichichinja, node yekutanga inobata node yemubatanidzwa, iyo inovhura uye inoronga kutengeserana kwakagoverwa, kuchiita uchishandisa optimized two-phase commit protocol.
Iyo coordinator node inodzokororwa, saka kana murongi akatadza, iyo backup node inotora ipapo. Asi kana node ine data ikakundikana, saka nzira chete yekuwana data yayo ndeyekutangazve node. Sezvo mutemo, masumbu eHANA anochengetedza sevhavha kuitira kuti atangezve node yakarasika pairi nekukurumidza sezvinobvira.
Source: www.habr.com