Ithiyori ye-CAP iyisisekelo sethiyori yezinhlelo ezisabalalisiwe. Yebo, impikiswano ezungezile ayinciphi: izincazelo ezikuyo azikho emthethweni, futhi abukho ubufakazi obuqinile... Noma kunjalo, simi ngokuqinile ezikhundleni zomqondo ovamile wansuku zonke™, siyaqonda ngokunembile ukuthi ithiyori iyiqiniso.
Okuwukuphela kwento engabonakali incazelo yencwadi ethi "P". Uma iqoqo lihlukaniswa, liyanquma ukuthi lingaphenduli kuze kufinyelelwe ikhoramu, noma libuyisele idatha etholakalayo. Ngokuya ngemiphumela yalokhu kukhetha, isistimu ihlukaniswa njenge-CP noma i-AP. I-Cassandra, isibonelo, ingaziphatha noma iyiphi indlela, kuncike ngisho nezilungiselelo zeqoqo, kodwa ngemingcele yesicelo ngasinye. Kodwa uma isistimu ingeyona "P" futhi ihlukana, kuthiwani?
Impendulo yalo mbuzo ngandlela-thile ayilindelekile: iqoqo le-CA alikwazi ukuhlukana.
Hlobo luni lweqoqo elingakwazi ukuhlukana?
Isici esibalulekile seqoqo elinjalo wuhlelo lokugcinwa kwedatha okwabelwana ngalo. Ezimweni eziningi, lokhu kusho ukuxhuma phezu kwe-SAN, okukhawulela ukusetshenziswa kwezixazululo ze-CA kumabhizinisi amakhulu akwazi ukugcina ingqalasizinda ye-SAN. Ukuze amaseva amaningi asebenze nedatha efanayo, isistimu yefayela ehlanganisiwe iyadingeka. Amasistimu anjalo amafayela ayatholakala kumaphothifoliyo e-HPE (CFS), Veritas (VxCFS) kanye ne-IBM (GPFS).
I-Oracle RAC
Inketho ye-Real Application Cluster yaqala ukuvela ngo-2001 ngokukhishwa kwe-Oracle 9i. Kuqoqo elinjalo, izimo zeseva ezimbalwa zisebenza nesizindalwazi esifanayo.
I-Oracle ingasebenza ngazo zombili isistimu yefayela ehlanganisiwe nesixazululo sayo - i-ASM, Ukuphathwa Kwesitoreji Okuzenzakalelayo.
Ikhophi ngayinye igcina ijenali yayo. Umsebenzi wenziwa futhi wenziwa yisibonelo esisodwa. Uma isibonelo sihluleka, enye yama-cluster nodes asele (isibonelo) ifunda ilogi yayo bese ibuyisela idatha elahlekile - ngaleyo ndlela iqinisekise ukutholakala.
Zonke izimo zigcina inqolobane yazo, futhi amakhasi afanayo (amabhulokhi) angaba kunqolobane yezimo eziningi ngesikhathi esisodwa. Ngaphezu kwalokho, uma isibonelo esisodwa sidinga ikhasi futhi lisenqolobaneni yesinye isenzakalo, singalithola kumakhelwane waso lisebenzisa indlela yokuhlanganisa inqolobane esikhundleni sokufunda kudiski.
Kodwa kwenzekani uma esinye sezimo sidinga ukushintsha idatha?
Okukhethekile kwe-Oracle ukuthi ayinayo isevisi yokukhiya ezinikele: uma iseva ifuna ukukhiya umugqa, irekhodi lokukhiya libekwa ngqo ekhasini lememori lapho umugqa okhiyiwe utholakala khona. Ngenxa yale ndlela, i-Oracle ingumpetha wokusebenza phakathi kwesizindalwazi se-monolithic: isevisi yokukhiya ayilokothi ibe ibhodlela. Kodwa ekucushweni kweqoqo, i-architecture enjalo ingaholela kuthrafikhi eshubile yenethiwekhi kanye ne-deadlocks.
Uma irekhodi selikhiyiwe, isenzakalo sazisa zonke ezinye izimo ukuthi ikhasi eligcina lelo rekhodi linokubanjwa okukhethekile. Uma esinye isenzakalo sidinga ukushintsha irekhodi ekhasini elifanayo, kufanele lilinde kuze kube yilapho izinguquko zekhasi zenziwe, okungukuthi, ulwazi loshintsho lubhalwa kujenali kudiski (futhi ukuthengiselana kungaqhubeka). Kungase futhi kwenzeke ukuthi ikhasi lizoshintshwa ngokulandelana ngamakhophi amaningana, bese kuthi lapho ubhala ikhasi kudiski kuzodingeka uthole ukuthi ubani ogcina inguqulo yamanje yaleli khasi.
Ukubuyekeza ngokungahleliwe amakhasi afanayo kuwo wonke amanodi e-RAC ahlukahlukene kubangela ukusebenza kwesizindalwazi kwehle kakhulu, kuze kube seqophelweni lapho ukusebenza kweqoqo kungaba ngaphansi kwalokho kwesenzakalo esisodwa.
Ukusetshenziswa okulungile kwe-Oracle RAC ukuhlukanisa idatha ngokoqobo (isibonelo, kusetshenziswa indlela yethebula elihlukanisiwe) futhi ufinyelele isethi ngayinye yama-partitions ngokusebenzisa inodi ezinikele. Inhloso enkulu ye-RAC bekungekona ukukala okuvundlile, kodwa ukuqinisekisa ukubekezelelana kwamaphutha.
Uma i-node iyeka ukuphendula ekushayeni kwenhliziyo, i-node eyitholile iqala inqubo yokuvota kudiski. Uma i-node engekho ingaphawulwa lapha, enye yama-node ithatha umthwalo wokuthola kabusha idatha:
- "ifriza" wonke amakhasi abesenqolobaneni yenodi engekho;
- ifunda amalogi (iphinde yenza kabusha) yenodi engekho futhi iphinde isebenzise izinguquko ezirekhodiwe kulawa malogi, ngesikhathi esifanayo ihlola ukuthi ingabe amanye ama-node anezinguqulo zakamuva kakhulu zamakhasi ashintshwayo;
- ibuyisela emuva imisebenzi elindile.
Ukuze kube lula ukushintsha phakathi kwamanodi, i-Oracle inomqondo wesevisi - isibonelo esibonakalayo. Isibonelo singanikeza izinsizakalo eziningi, futhi isevisi ingahamba phakathi kwamanodi. Isibonelo sohlelo lokusebenza esinikeza ingxenye ethile yesizindalwazi (isibonelo, iqembu lamakhasimende) sisebenza nesevisi eyodwa, futhi isevisi ebhekele le ngxenye yesizindalwazi ithuthela kwenye indawo lapho i-node ihluleka.
I-IBM Pure Data Systems for Transactions
Isixazululo seqoqo le-DBMS savela kuphothifoliyo yeBlue Giant ngo-2009. Ngokombono, ilandela iqoqo le-Parallel Sysplex, elakhelwe phezu kwemishini “evamile”. Ngo-2009, i-DB2 pureScale, i-software suite, yakhululwa, kwathi ngo-2012, i-IBM yanikeza umshini obizwa ngokuthi iPure Data Systems for Transactions. Akufanele kudidaniswe nePure Data Systems for Analytics, okungeyona into edlula iNetezza eqanjwe kabusha.
Ekuboneni kokuqala, i-pureScale architecture ifana ne-Oracle RAC: ngendlela efanayo, ama-node amaningana axhunywe ohlelweni oluvamile lokugcina idatha, futhi i-node ngayinye iqhuba isibonelo sayo se-DBMS ngezindawo zayo zememori kanye nezingodo zokuthengiselana. Kodwa, ngokungafani ne-Oracle, i-DB2 inesevisi yokukhiya ezinikele emelwe isethi yezinqubo ze-db2LLM*. Ekucushweni kweqoqo, le sevisi ibekwe endaweni ehlukile, ebizwa nge-coupling facility (CF) ku-Parallel Sysplex, kanye ne-PowerHA ku-Pure Data.
I-PowerHA inikeza lezi zinsizakalo ezilandelayo:
- umphathi wokukhiya;
- inqolobane ye-buffer global;
- indawo yezokuxhumana.
Ukuze udlulise idatha isuka ku-PowerHA iye kusizindalwazi nangemuva, kusetshenziswa ukufinyelela kwememori okukude, ngakho ukuxhuma kweqoqo kufanele kusekele umthetho olandelwayo we-RDMA. I-PureScale ingasebenzisa kokubili i-Infiniband ne-RDMA nge-Ethernet.
Uma i-node idinga ikhasi, futhi leli khasi alikho kunqolobane, khona-ke i-node icela ikhasi kunqolobane yomhlaba wonke, futhi kuphela uma ingekho, iyifunda kudiski. Ngokungafani ne-Oracle, isicelo siya ku-PowerHA kuphela, hhayi kumanodi angomakhelwane.
Uma isibonelo sizoshintsha umugqa, siwukhiya kumodi ekhethekile, kanye nekhasi lapho umugqa utholakala kwimodi eyabiwe. Wonke amalokhi abhaliswe kumphathi wokukhiya womhlaba. Lapho okwenziwayo kuqedwa, inodi ithumela umlayezo kumphathi wokukhiya, okopisha ikhasi elishintshiwe kunqolobane yomhlaba wonke, akhulule izingidi, futhi enze ikhasi eliguquliwe lingasebenzi kuma-cache amanye.
Uma ikhasi lapho umugqa oguquliwe likhona selikhiyiwe kakade, umphathi wokukhiya uzofunda ikhasi elishintshiwe kumemori yenodi elenze ushintsho, akhulule isikhiya, enze ikhasi eliguquliwe lingasebenzi kunqolobane yamanye amanodi, futhi nikeza ukukhiya kwekhasi endaweni eyicelile.
"Okungcolile", okungukuthi, ashintshiwe, amakhasi angabhalwa kudiski kokubili kusuka ku-node evamile futhi kusukela ku-PowerHA (castout).
Uma enye yamanodi e-pureScale ihluleka, ukutholwa kukhawulelwe kulokho kuphela okwenziwe okwakungakaqedwa ngesikhathi sokwehluleka: amakhasi alungiswe yileyo nodi emisebenzini eqediwe akunqolobane yomhlaba wonke ku-PowerHA. I-node iqala kabusha ekucushweni okuncishisiwe kwenye yeziphakeli ku-cluster, ihlehlela emuva okwenziwayo okulindile futhi ikhiphe izingidi.
I-PowerHA isebenza kumaseva amabili futhi inodi eyinhloko iphindaphinda isimo sayo ngokuvumelanisa. Uma i-PowerHA node eyinhloko yehluleka, iqoqo liyaqhubeka nokusebenza ngenodi yokusekelayo.
Kunjalo, uma ufinyelela idatha esethwe ngenodi eyodwa, ukusebenza kukonke kweqoqo kuzoba phezulu. I-PureScale ingabona nokuthi indawo ethile yedatha icutshungulwa inodi eyodwa, bese wonke amalokhi ahlobene naleyo ndawo azocutshungulwa endaweni nge-node ngaphandle kokuxhumana ne-PowerHA. Kodwa ngokushesha nje lapho uhlelo lokusebenza luzama ukufinyelela le datha ngenye i-node, ukucutshungulwa kokukhiya okumaphakathi kuzoqala kabusha.
Ukuhlolwa kwangaphakathi kwe-IBM kumthwalo womsebenzi ongu-90% ofundiwe futhi u-10% ubhale, ofana kakhulu nomsebenzi wokukhiqiza wangempela womhlaba, ubonisa ukukala cishe komugqa kufika kumanodi ayi-128. Izimo zokuhlola, ngeshwa, azidalulwa.
I-HPE NonStop SQL
Iphothifoliyo ye-Hewlett-Packard Enterprise nayo inendawo yayo etholakala kakhulu. Lena inkundla ye-NonStop, eyakhishwa emakethe ngo-1976 ngabakwaTandem Computers. Ngo-1997, inkampani yatholwa yiCompaq, yona eyahlanganiswa noHewlett-Packard ngo-2002.
I-NonStop isetshenziselwa ukwakha izinhlelo zokusebenza ezibalulekile - isibonelo, i-HLR noma ukucubungula amakhadi asebhange. Isiteji sihanjiswa ngendlela ye-software kanye ne-hardware complex (umshini), ohlanganisa izindawo zekhompyutha, uhlelo lokugcina idatha kanye nemishini yokuxhumana. Inethiwekhi ye-ServerNet (kuzinhlelo zesimanje - i-Infiniband) isebenza kokubili ukushintshanisa phakathi kwama-node kanye nokufinyelela ohlelweni lokugcina idatha.
Izinguqulo zakuqala zesistimu zasebenzisa amaprosesa okuphathelene avunyelaniswe komunye nomunye: yonke imisebenzi yenziwa ngokuhambisana namaphrosesa amaningana, futhi ngokushesha nje lapho omunye wabaprosesa enze iphutha, yavalwa, futhi eyesibili yaqhubeka nokusebenza. Kamuva, uhlelo lwashintshela kumaphrosesa avamile (i-MIPS yokuqala, kwase kulandela i-Itanium futhi ekugcineni i-x86), nezinye izindlela zaqala ukusetshenziselwa ukuvumelanisa:
- imilayezo: inqubo yesistimu ngayinye inewele "lethunzi", lapho inqubo esebenzayo ithumela khona ngezikhathi ezithile imilayezo mayelana nesimo sayo; uma inqubo eyinhloko ihluleka, inqubo yesithunzi iqala ukusebenza kusukela ngesikhathi esinqunywa umlayezo wokugcina;
- ukuvota: isistimu yesitoreji inengxenye yehadiwe ekhethekile eyamukela ukufinyelela okufanayo okuningi futhi ikwenze kuphela uma ukufinyelela kufana; Esikhundleni sokuvumelanisa ngokomzimba, amaphrosesa asebenza ngokulinganayo, futhi imiphumela yomsebenzi wawo iqhathaniswa kuphela ngezikhathi ze-I/O.
Kusukela ngo-1987, i-DBMS ehlobene ibisebenza endaweni ye-NonStop - okokuqala i-SQL/MP, futhi kamuva i-SQL/MX.
Yonke imininingwane egciniwe ihlukaniswe yaba izingxenye, futhi ingxenye ngayinye inesibopho senqubo yayo Yomphathi Wokufinyelela Idatha (DAM). Ihlinzeka ngokurekhoda idatha, ukugcinwa kwesikhashana, kanye nezindlela zokukhiya. Ukucubungula idatha kwenziwa Izinqubo Zeseva Yefa ezisebenza ezindaweni ezifanayo njengabaphathi bedatha abahambisanayo. Isihleli se-SQL/MX sihlukanisa imisebenzi phakathi kwabenzi bomsebenzi futhi sihlanganisa imiphumela. Uma kudingekile ukwenza izinguquko okuvunyelwene ngazo, umthetho olandelwayo wokuzibophezela wezigaba ezimbili ohlinzekwa umtapo wezincwadi we-TMF (Transaction Management Facility) uyasetshenziswa.
I-NonStop SQL ingakwazi ukubeka phambili izinqubo ukuze imibuzo emide yokuhlaziya ingaphazamisi ukwenza umsebenzi. Nokho, injongo yakhona ukucutshungulwa kwemisebenzi emifushane, hhayi izibalo. Unjiniyela uqinisekisa ukutholakala kweqoqo le-NonStop ezingeni lama-“nines” amahlanu, okungukuthi, isikhathi sokuphumula siyimizuzu emi-5 kuphela ngonyaka.
SAP-HANA
Ukukhishwa kokuqala okuzinzile kwe-HANA DBMS (1.0) kwenzeka ngoNovemba 2010, futhi iphakheji ye-SAP ERP yashintshela ku-HANA ngoMeyi 2013. Isiteji sisekelwe kubuchwepheshe obuthengiwe: Injini Yokusesha ye-TREX (sesha kusitoreji sekholomu), i-P*TIME DBMS kanye ne-MAX DB.
Igama elithi “HANA” ngokwalo liyisifinyezo, Ukusebenza okuphezulu kwe-Analytical Appliance. Le DBMS inikezwa ngohlobo lwekhodi engasebenza kunoma yiziphi iziphakeli ze-x86, nokho, ukufakwa kwezimboni kuvunyelwe kuphela kumishini eqinisekisiwe. Izixazululo zitholakala ku-HP, Lenovo, Cisco, Dell, Fujitsu, Hitachi, NEC. Okunye ukulungiselelwa kwe-Lenovo kuze kuvumele ukusebenza ngaphandle kwe-SAN - indima yohlelo olujwayelekile lokugcina idlalwa yiqoqo le-GPFS kumadiski endawo.
Ngokungafani nezinkundla ezibalwe ngenhla, i-HANA iyi-DBMS esenkumbulo, okungukuthi isithombe sedatha eyinhloko sigcinwa ku-RAM, futhi amalogi kuphela nezifinyezo zezikhathi ezithile ezibhalwa kudiski ukuze zilulame uma kwenzeka kuba nenhlekelele.
I-HANA cluster node ngayinye inesibopho sengxenye yayo yedatha, futhi imephu yedatha igcinwa engxenyeni ekhethekile - i-Name Server, etholakala endaweni yomxhumanisi. Idatha ayiphindi phakathi kwamanodi. Ulwazi lokukhiya nalo lugcinwa endaweni ngayinye, kodwa uhlelo lunomtshina wokuvala i-global deadlock.
Lapho iklayenti le-HANA lixhuma kuqoqo, lilanda i-topology yalo futhi lingakwazi ukufinyelela kunoma iyiphi indawo ngokuqondile, kuye ngokuthi iyiphi idatha eliyidingayo. Uma ukuthengiselana kuthinta idatha yenodi eyodwa, khona-ke kungenziwa endaweni ngaleyo node, kodwa uma idatha yamanodi amaningana ishintsha, i-node yokuqala ithinta i-coordinator node, evula futhi ixhumanise ukuthengiselana okusabalalisiwe, ikwenze kusetshenziswa i-node. iphrothokholi yokuzibophezela elungiselelwe izigaba ezimbili.
I-node yomxhumanisi iphindwe kabili, ngakho-ke uma umxhumanisi ehluleka, i-node yokusekelayo ithatha ngokushesha. Kodwa uma i-node enedatha ihluleka, khona-ke ukuphela kwendlela yokufinyelela idatha yayo ukuqala kabusha i-node. Njengomthetho, amaqoqo e-HANA agcina iseva eyisipele ukuze kuqalwe kabusha i-node elahlekile kuyo ngokushesha okukhulu.
Source: www.habr.com