{"id":75726,"date":"2020-03-28T07:42:08","date_gmt":"2020-03-28T05:42:08","guid":{"rendered":"https:\/\/prohoster.info\/blog\/administrirovanie\/klaster-iz-dvuh-uzlov-dyavol-v-detalyah"},"modified":"2020-03-28T07:42:08","modified_gmt":"2020-03-28T05:42:08","slug":"klaster-iz-dvuh-uzlov-dyavol-v-detalyah","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/klaster-iz-dvuh-uzlov-dyavol-v-detalyah","title":{"rendered":"Kluster i dy nyjave \u2013 djalli \u00ebsht\u00eb n\u00eb detaje","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>P\u00ebrsh\u00ebndetje, Habr! Po ju prezantoj nj\u00eb p\u00ebrkthim t\u00eb artikullit <noindex><a rel=\"nofollow\" href=\"http:\/\/blog.clusterlabs.org\/blog\/2018\/two-node-problems\">\u00abDy Dyt\u00eb \u2014 Djalli q\u00eb Q\u00ebndron n\u00eb Detaje\u00bb<\/a><\/noindex> autori Andrew Beekhof.<\/p>\n<p>Shum\u00eb njer\u00ebz preferojn\u00eb klaster\u00ebt me dy nyje sepse ata duken konceptualisht m\u00eb t\u00eb thjesht\u00eb, p\u00ebr m\u00eb tep\u00ebr jan\u00eb 33% m\u00eb t\u00eb lir\u00eb se homolog\u00ebt e tyre me tre nyje. Edhe pse \u00ebsht\u00eb krejt\u00ebsisht e mundur t\u00eb krijosh nj\u00eb klaster t\u00eb mir\u00eb me dy nyje, n\u00eb shumic\u00ebn e rasteve, p\u00ebr shkak t\u00eb skenar\u00ebve t\u00eb paqen\u00ebsuar, nj\u00eb konfigurim i till\u00eb do t\u00eb krijoj\u00eb shum\u00eb probleme t\u00eb paqarta.<br \/>\n<noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><br \/>\nHapi i par\u00eb drejt krijimit t\u00eb \u00e7do sistemi meDisponueshm\u00ebri t\u00eb Lart\u00eb \u00ebsht\u00eb identifikimi dhe p\u00ebrpjekja p\u00ebr t\u00eb eliminuar piketat e vetme t\u00eb d\u00ebshtimit, shpesh t\u00eb p\u00ebrmbledhura si <i>SPoF<\/i> (pik\u00eb e vetme d\u00ebshtimi).<\/p>\n<p>Duhet t\u00eb mbahet mend se n\u00eb \u00e7do sistem nuk \u00ebsht\u00eb e mundur t\u00eb eliminohen t\u00eb gjitha rreziqet e mundshme t\u00eb nd\u00ebrprerjes. Kjo rrjedh s\u00eb paku nga fakti se mbrojtja tipike kund\u00ebr rrezikut \u00ebsht\u00eb futja e ndonj\u00eb redundance, q\u00eb \u00e7on n\u00eb rritjen e kompleksitetit t\u00eb sistemit dhe krijimin e pikave t\u00eb reja t\u00eb d\u00ebshtimit. Prandaj, ne n\u00eb fillim pranojm\u00eb nj\u00eb kompromis dhe p\u00ebrqendrohemi n\u00eb ngjarjet q\u00eb lidhen me pik\u00eb e vetme d\u00ebshtimi, n\u00eb vend t\u00eb lidhjeve t\u00eb ngjarjeve dhe, p\u00ebr rrjedhoj\u00eb, gjithnj\u00eb e m\u00eb pak t\u00eb mundshme.<\/p>\n<p>Duke pasur parasysh kompromiset, ne jo vet\u00ebm q\u00eb k\u00ebrkojm\u00eb SPoF, por gjithashtu realizojm\u00eb nj\u00eb ekuilib\u00ebr mezi p\u00ebr rreziqet dhe pasojat, si rezultat, p\u00ebrfundimi se \u00e7far\u00eb \u00ebsht\u00eb kritik dhe \u00e7far\u00eb jo mund t\u00eb ndryshoj\u00eb p\u00ebr \u00e7do implementim.<\/p>\n<blockquote><p>Nuk i nevojiten t\u00eb gjith\u00ebve ofrues alternativ\u00eb energjie me linja elektrike t\u00eb pavarura. Megjithat\u00eb, paranoia ia doli p\u00ebr nj\u00eb klient, kur monitorimi i tyre zbuloi nj\u00eb transformator t\u00eb defekt. Klienti telefonoi duke u p\u00ebrpjekur t\u00eb paralajm\u00ebroj\u00eb kompanin\u00eb e energjis\u00eb, derisa transformatori i defekt nuk shp\u00ebrtheu.<\/p><\/blockquote>\n<p>\nNj\u00eb pik\u00eb fillestare natyrale \u00ebsht\u00eb t\u00eb kesh m\u00eb shum\u00eb se nj\u00eb nyje n\u00eb sistem. Megjithat\u00eb, para se sistemi t\u00eb jet\u00eb n\u00eb gjendje t\u00eb transferoj\u00eb sh\u00ebrbimet n\u00eb nyj\u00ebn e mbetur pas d\u00ebshtimit, n\u00eb p\u00ebrgjith\u00ebsi, \u00ebsht\u00eb e nevojshme t\u00eb sigurohemi q\u00eb sh\u00ebrbimet e transferuara nuk jan\u00eb aktive n\u00eb ndonj\u00eb vend tjet\u00ebr.<\/p>\n<p>Nj\u00eb klaster me dy nyje nuk ka disavantazhe n\u00ebse si rezultat i d\u00ebshtimit t\u00eb dy nyjet sh\u00ebrbejn\u00eb t\u00eb nj\u00ebjtin faqe statike. Megjithat\u00eb, gjith\u00e7ka ndryshon n\u00ebse t\u00eb dyja pal\u00ebt menaxhojn\u00eb n\u00eb m\u00ebnyr\u00eb t\u00eb pavarur nj\u00eb radh\u00eb t\u00eb p\u00ebrbashk\u00ebt t\u00eb pun\u00ebve ose ofrojn\u00eb akses t\u00eb paorganizuar p\u00ebr t\u00eb shkruar n\u00eb nj\u00eb baz\u00eb t\u00eb dh\u00ebnash t\u00eb replikuar ose n\u00eb nj\u00eb sistem t\u00eb p\u00ebrbashk\u00ebt skedar\u00ebsh.<\/p>\n<p>Prandaj, p\u00ebr t\u00eb parandaluar d\u00ebmtimin e t\u00eb dh\u00ebnave si rezultat i d\u00ebshtimit t\u00eb nj\u00eb nyje \u2013 ne mb\u00ebshtetemi n\u00eb at\u00eb q\u00eb quhet <i>\u00abndarje\u00bb<\/i> (fencing).<\/p>\n<h2>Principi i ndarjes<\/h2>\n<p>\nN\u00eb thelb t\u00eb principit t\u00eb ndarjes q\u00ebndron pyetja: a mund t\u00eb d\u00ebmtoj\u00eb nj\u00eb nyje konkurruese t\u00eb dh\u00ebnat? N\u00ebse d\u00ebmtimi i t\u00eb dh\u00ebnave \u00ebsht\u00eb nj\u00eb skenar i mundsh\u00ebm \u2013 nj\u00eb zgjidhje e mir\u00eb do t\u00eb ishte izolimi i nyjes nga k\u00ebrkesat e ardhshme, si dhe nga ruajtja e q\u00ebndrueshme. Qasja m\u00eb e zakonshme ndaj ndarjes \u2013 \u00ebsht\u00eb shk\u00ebputja e nyjeve problematike.<\/p>\n<p>Ka dy kategori metodash ndarjeje q\u00eb un\u00eb do t'i quaja <i>direkte<\/i> dhe <i>t\u00eb t\u00ebrthorta<\/i>, por nj\u00eblloj mund t\u00eb quhen <i>aktive<\/i> dhe <i>pasive<\/i>. Metodat direkte p\u00ebrfshijn\u00eb veprime nga nyjet e mbijetuar t\u00eb barabarta, t\u00eb tilla si nd\u00ebrveprimi me pajisjen IPMI (Interface p\u00ebr Menaxhimin e Platform\u00ebs Inteligjente) ose iLO (mekanizmi i menaxhimit t\u00eb server\u00ebve n\u00eb kushte munges\u00eb fizike t\u00eb qasjes n\u00eb to), nd\u00ebrsa metodat e t\u00ebrthorta mb\u00ebshteten te nyja e d\u00ebshtuar p\u00ebr t\u00eb njohur ndonj\u00eb m\u00ebnyr\u00eb se \u00ebsht\u00eb n\u00eb nj\u00eb gjendje t\u00eb keqe (ose, t\u00eb pakt\u00ebn, e pengon pjes\u00ebn tjet\u00ebr t\u00eb rikuperohet) dhe sinjalizimin e <noindex><a rel=\"nofollow\" href=\"https:\/\/en.wikipedia.org\/wiki\/Watchdog_timer\">hardware watchdog<\/a><\/noindex> rreth nevoj\u00ebs p\u00ebr t\u00eb shk\u00ebputur nyjen e d\u00ebshtuar.<\/p>\n<p>Kvorumi ndihmon n\u00eb rastin e p\u00ebrdorimit t\u00eb metodave si direkte ashtu edhe t\u00eb t\u00ebrthorta.<\/p>\n<h3>Ndarje direkte<\/h3>\n<p>\nN\u00eb rastin e ndarjes direkte ne mund t\u00eb p\u00ebrdorim kvorumin p\u00ebr t\u00eb parandaluar garat e ndarjes n\u00eb rast t\u00eb d\u00ebshtimit t\u00eb rrjetit.<\/p>\n<p>Duke pasur konceptin e kvorumit, sistemi ka informacion t\u00eb mjaftuesh\u00ebm (edhe pa u lidhur me partner\u00ebt e tij), p\u00ebr sa i p\u00ebrket n\u00ebse nyjet duhet t\u00eb nisin ndarjen dhe \/ ose rikuperimin.<\/p>\n<p>Pa kvorum, t\u00eb dyja pal\u00ebt e ndarjes s\u00eb rrjetit t\u00eb supozojn\u00eb p\u00ebr drejt\u00eb se pala tjet\u00ebr \u00ebsht\u00eb e vdekur dhe do t\u00eb p\u00ebrpiqen t\u00eb ndajn\u00eb tjetrin. N\u00eb rastin m\u00eb t\u00eb keq, t\u00eb dy pal\u00ebt arrijn\u00eb t\u00eb shk\u00ebputin t\u00eb gjith\u00eb klasterin. Skenari alternativ \u2013 deathmatch, nj\u00eb cik\u00ebl p\u00ebrjet\u00ebsisht nyjesh q\u00eb shfaqen, nuk i shohin pirun\u00ebt e tyre, i rikthejn\u00eb dhe nisin rikuperimin vet\u00ebm p\u00ebr t'u rikthyer, kur piru i tyre kalon n\u00eb t\u00eb nj\u00ebjtin logic.<\/p>\n<p>Problemi me ndarjen q\u00ebndron n\u00eb faktin se pajisjet m\u00eb t\u00eb p\u00ebrdorura b\u00ebhen t\u00eb paarritshme p\u00ebr shkak t\u00eb t\u00eb nj\u00ebjtave ngjarjeve t\u00eb d\u00ebshtimit, p\u00ebr t\u00eb cilat ne duam t\u00eb orientoheshim p\u00ebr t\u00eb rimarr\u00eb. Shumica e kartave IPMI dhe iLO jan\u00eb instaluar n\u00eb host-et q\u00eb ata kontrollojn\u00eb dhe, sipas parazgjedhjes, p\u00ebrdorin t\u00eb nj\u00ebjtin rrjet, q\u00eb e b\u00ebn q\u00eb nodet p\u00ebr q\u00ebllim t\u00eb mendojn\u00eb se nodet e tjera jan\u00eb offline.<\/p>\n<p>Fatkeq\u00ebsisht, karakteristikat e funksionimit t\u00eb pajisjeve IPMI dhe iLO rrall\u00eb shqyrtohen n\u00eb momentin e blerjes s\u00eb pajisjeve.<\/p>\n<h3>Ndarje e shkall\u00ebzuar<\/h3>\n<p>\nKvorumi \u00ebsht\u00eb gjithashtu i r\u00ebnd\u00ebsish\u00ebm p\u00ebr menaxhimin e ndarjeve t\u00eb shkall\u00ebzuara, n\u00ebse gjith\u00e7ka b\u00ebhet si duhet, kvorumi mund t\u00eb lejoj\u00eb mbijetuesit t\u00eb supozojn\u00eb se nodet e humbura do t\u00eb kalojn\u00eb n\u00eb nj\u00eb gjendje t\u00eb sigurt pas nj\u00eb periudhe t\u00eb caktuar.<\/p>\n<p>Me nj\u00eb konfigurim t\u00eb till\u00eb, timer-i i hardware watchdog reset-et \u00e7do N sekonda, n\u00ebse kvorumi nuk \u00ebsht\u00eb humbur. N\u00ebse timer-i (zakonisht disa her\u00eb N) skadon, pajisja kryen nj\u00eb fikje t\u00eb papritur t\u00eb energjis\u00eb (jo shutdown).<\/p>\n<p>Ky qasje \u00ebsht\u00eb shum\u00eb efikase, por pa nj\u00eb kvorum p\u00ebr ta menaxhuar, informacioni brenda grupit \u00ebsht\u00eb i pamjaftuesh\u00ebm. Nuk \u00ebsht\u00eb e leht\u00eb t\u00eb p\u00ebrcaktosh diferenc\u00ebn midis ndalimit t\u00eb rrjetit dhe d\u00ebshtimit t\u00eb nodit partner. Arsyeja pse kjo ka r\u00ebnd\u00ebsi \u00ebsht\u00eb se pa aft\u00ebsin\u00eb p\u00ebr t\u00eb dalluar k\u00ebto dy raste, jeni t\u00eb detyruar t\u00eb zgjidhni t\u00eb nj\u00ebjtin m\u00ebnyr\u00eb veprimi n\u00eb t\u00eb dyja rastet.<\/p>\n<p>Problemi me zgjedhjen e nj\u00eb m\u00ebnyre veprimi \u00ebsht\u00eb se nuk ka nj\u00eb procedur\u00eb veprimi q\u00eb maksimizon disponueshm\u00ebrin\u00eb dhe parandalon humbjen e t\u00eb dh\u00ebnave.<\/p>\n<ul>\n<li>N\u00ebse vendosni t\u00eb supozoni se nodi partner \u00ebsht\u00eb aktiv, por n\u00eb t\u00eb v\u00ebrtet\u00eb ka ndodhur nj\u00eb d\u00ebshtim, grupi do t\u00eb ndaloj\u00eb tep\u00ebr sh\u00ebrbimet q\u00eb do t\u00eb duhej t\u00eb funksiononin p\u00ebr t\u00eb kompensuar humbjen e sh\u00ebrbimeve t\u00eb nodit partner q\u00eb ka r\u00ebn\u00eb.<\/li>\n<li>N\u00ebse vendosni t\u00eb supozoni se nodi nuk funksionon, por ishte thjesht nj\u00eb d\u00ebshtim i rrjetit dhe n\u00eb t\u00eb v\u00ebrtet\u00eb nodi n\u00eb distanc\u00eb po funksionon, at\u00ebher\u00eb, n\u00eb m\u00eb t\u00eb mir\u00ebn, ju po n\u00ebnshkruani nj\u00eb kontroll manual t\u00eb ardhsh\u00ebm t\u00eb grupeve t\u00eb t\u00eb dh\u00ebnave t\u00eb rezultuar.<\/li>\n<\/ul>\n<p>\nPavar\u00ebsisht se \u00e7far\u00eb heuristik do t\u00eb p\u00ebrdorni, \u00ebsht\u00eb triviale t\u00eb krijoni nj\u00eb d\u00ebshtim q\u00eb do t\u00eb detyroj\u00eb t\u00eb dyja an\u00ebt t\u00eb punojn\u00eb, ose do t\u00eb detyroj\u00eb grupin t\u00eb fik\u00eb nodet e mbetura. Mos p\u00ebrdorimi i kvorumit v\u00ebrtet i heq grupit nj\u00eb nga mjetet m\u00eb t\u00eb fuqishme n\u00eb arsenalin e tij.<\/p>\n<p>N\u00ebse nuk ka alternativ\u00eb tjet\u00ebr, qasja m\u00eb e mir\u00eb do t\u00eb jet\u00eb t\u00eb hiqni dor\u00eb nga disponueshm\u00ebria (k\u00ebtu autori i referohet teorem\u00ebs CAP). Disponueshm\u00ebria e lart\u00eb e t\u00eb dh\u00ebnave t\u00eb prishura nuk ndihmon ask\u00ebnd, dhe verifikimi manual i grupeve t\u00eb ndryshme t\u00eb t\u00eb dh\u00ebnave gjithashtu nuk sjell k\u00ebnaq\u00ebsi.<\/p>\n<h2>Kvorumi<\/h2>\n<p>\nKvorumi ting\u00ebllon bukur, a nuk \u00ebsht\u00eb?<\/p>\n<p>E vetmja mang\u00ebsi \u00ebsht\u00eb se p\u00ebr ta pasur at\u00eb n\u00eb nj\u00eb grup me N an\u00ebtar\u00eb, ju nevojitet q\u00eb t\u00eb mbetet lidhja midis N \/ 2 + 1 nga nyjat tuaja. Kjo \u00ebsht\u00eb e pamundur n\u00eb nj\u00eb grup me dy nyje pas d\u00ebshtimit t\u00eb nj\u00eb nyje.<\/p>\n<p>\u00c7ka p\u00ebrfundimisht na \u00e7on n\u00eb problemin themelor me dy nyje:<br \/>\nkvorumi nuk ka kuptim n\u00eb grupet me dy nyje, dhe pa at\u00eb \u00ebsht\u00eb e pamundur t\u00eb p\u00ebrcaktohet besuesh\u00ebm kursi i veprimit q\u00eb maksimizon disponueshm\u00ebrin\u00eb dhe parandalon humbjen e t\u00eb dh\u00ebnave.<br \/>\nEdhe n\u00eb nj\u00eb sistem me dy nyje, t\u00eb lidhura me nj\u00eb kabllo nd\u00ebrkufitare, \u00ebsht\u00eb e pamundur t\u00eb b\u00ebhet nj\u00eb dallim p\u00ebrfundimtar midis \u00e7aktivizimit t\u00eb rrjetit dhe d\u00ebshtimit t\u00eb nj\u00eb nyje tjet\u00ebr. \u00c7aktivizimi i nj\u00ebr\u00ebs skaj (probabiliteti i t\u00eb cilit, pa dyshim, \u00ebsht\u00eb proporcionale me distanc\u00ebn midis nyjeve) do t\u00eb ishte e mjaftueshme p\u00ebr t\u00eb hedhur posht\u00eb \u00e7do supozim se funksionimi i kanalit \u00ebsht\u00eb i barabart\u00eb me sh\u00ebndetin e nyj\u00ebs partner.<\/p>\n<h3>T\u00eb b\u00ebjm\u00eb t\u00eb funksionoj\u00eb nj\u00eb grup me dy nyje<\/h3>\n<p>\nNdonj\u00ebher\u00eb, klienti nuk mund ose nuk d\u00ebshiron t\u00eb blej\u00eb nj\u00eb nyje t\u00eb tret\u00eb, dhe ne jemi t\u00eb detyruar t\u00eb k\u00ebrkojm\u00eb nj\u00eb alternativ\u00eb.<\/p>\n<h4>Opsioni 1 \u2013 Metoda e dyfishimit t\u00eb ndarjes<\/h4>\n<p>\nDispositivi i iLO ose IPMI i nyjes \u00ebsht\u00eb nj\u00eb pik\u00eb d\u00ebshtimi, pasi, n\u00eb rast d\u00ebshtimi, ato q\u00eb mbijetojn\u00eb nuk mund ta p\u00ebrdorin at\u00eb p\u00ebr t\u00eb rikthyer nyjen n\u00eb nj\u00eb gjendje t\u00eb sigurt. N\u00eb nj\u00eb grup me 3 ose m\u00eb shum\u00eb nyje, mund t\u00eb mitikojm\u00eb k\u00ebt\u00eb p\u00ebrmes llogaritjes s\u00eb kvorumit dhe p\u00ebrdorimit t\u00eb watch dog hardware (mekanizmi i ndarjes s\u00eb t\u00ebrthort\u00eb, si\u00e7 \u00ebsht\u00eb diskutuar m\u00eb par\u00eb). N\u00eb rastin e dy nyjeve, ne duhet t\u00eb p\u00ebrdorim n\u00eb vend t\u00eb k\u00ebsaj switch-e rrjeti t\u00eb furnizimit me energji (power distribution units ose PDUs).<\/p>\n<p>Pas d\u00ebshtimit, ajo q\u00eb mbijetoi s\u00eb pari p\u00ebrpiqet t\u00eb lidhet me dispozitivin kryesor t\u00eb ndarjes (iLO ose IPMI i integruar). N\u00ebse ia del, rikuperimi vazhdon si zakonisht. Vet\u00ebm n\u00eb rast d\u00ebshtimi t\u00eb pajisjes iLO \/ IPMI ndodh lidhja me PDU-n\u00eb, dhe n\u00ebse lidhja \u00ebsht\u00eb e suksesshme, rikuperimi mund t\u00eb vazhdoj\u00eb.<\/p>\n<p>Sigurohuni q\u00eb t\u00eb vendosni PDU-n\u00eb n\u00eb nj\u00eb rrjet t\u00eb ndrysh\u00ebm nga trafiku i klas\u00ebs, p\u00ebrndryshe nj\u00eb d\u00ebshtim i vet\u00ebm n\u00eb rrjet do t\u00eb bllokoj\u00eb aksesin si n\u00eb pajisjet e ndara ashtu edhe do t\u00eb bllokoj\u00eb rikuperimin e sh\u00ebrbimeve.<\/p>\n<p>K\u00ebtu mund t\u00eb pyesni \u2013 a nuk \u00ebsht\u00eb pajisja PDU nj\u00eb pik\u00eb e vetme d\u00ebshtimi? P\u00ebrgjigja \u00ebsht\u00eb \u2013 sigurisht q\u00eb \u00ebsht\u00eb.<\/p>\n<p>N\u00ebse ky rrezik \u00ebsht\u00eb i r\u00ebnd\u00ebsish\u00ebm p\u00ebr ju \u2013 nuk jeni vet\u00ebm: lidhni t\u00eb dy nodet me dy PDU dhe caktoni softuerin e klas\u00ebs t\u00eb p\u00ebrdor\u00eb t\u00eb dyja gjat\u00eb ndezjes dhe fikjes s\u00eb nod\u00ebve. Tani klasa mbetet aktive n\u00ebse nj\u00eb PDU vdes, dhe p\u00ebr t\u00eb bllokuar rikuperimin nevojitet nj\u00eb d\u00ebshtim tjet\u00ebr ose i nj\u00eb PDU tjet\u00ebr, ose i pajisjes IPMI.<\/p>\n<h4>Opsioni 2 \u2013 Shtimi i nj\u00eb arbitri<\/h4>\n<p>\nN\u00eb disa skenar\u00eb, ndon\u00ebse teknikisht metoda e ndarjes s\u00eb dyfisht\u00eb \u00ebsht\u00eb e mundur, ajo \u00ebsht\u00eb politikisht e komplikuar. Shum\u00eb kompani p\u00eblqejn\u00eb t\u00eb ken\u00eb nj\u00eb ndarje t\u00eb qart\u00eb midis administrator\u00ebve dhe pronar\u00ebve t\u00eb aplikacioneve, dhe administrator\u00ebt e rrjeteve q\u00eb shqet\u00ebsohen p\u00ebr sigurin\u00eb nuk jan\u00eb gjithmon\u00eb entuziast\u00eb p\u00ebr t\u00eb kaluar askujt parametrat e qasjes n\u00eb PDU.<\/p>\n<p>N\u00eb k\u00ebt\u00eb rast, alternativa e rekomanduar \u00ebsht\u00eb krijimi i nj\u00eb pale t\u00eb tret\u00eb neutrale, e cila mund t\u00eb plot\u00ebsoj\u00eb llogaritjen e kuorumit.<\/p>\n<p>N\u00eb rast d\u00ebshtimi, nodi duhet t\u00eb ket\u00eb mund\u00ebsin\u00eb t\u00eb shoh\u00eb eterin e partnerit t\u00eb tij ose arbitrit p\u00ebr t\u00eb rikuperuar sh\u00ebrbimet. Arbitri gjithashtu p\u00ebrfshin nj\u00eb funksion nd\u00ebrprerjeje, n\u00ebse t\u00eb dy nodet mund t\u00eb shohin arbitrin, por nuk shohin nj\u00ebri-tjetrin.<\/p>\n<p>Ky opsion duhet t\u00eb p\u00ebrdoret n\u00eb \u00e7ift me metod\u00ebn e t\u00ebrthort\u00eb t\u00eb ndarjes, si\u00e7 \u00ebsht\u00eb nj\u00eb timer hardware watchdog, i cili \u00ebsht\u00eb i vendosur p\u00ebr t\u00eb fikur makin\u00ebn n\u00ebse humbet lidhjen me partnerin e saj dhe arbitrin. N\u00eb k\u00ebt\u00eb m\u00ebnyr\u00eb, ai q\u00eb mbijetoi mund t\u00eb supozoj\u00eb me mjaft siguri se nodi i tij partner do t\u00eb jet\u00eb n\u00eb nj\u00eb gjendje t\u00eb sigurt pas skadimit t\u00eb timerit hardware watchdog.<\/p>\n<p>Dallimi praktik midis arbitrit dhe nodit t\u00eb tret\u00eb \u00ebsht\u00eb se arbitri k\u00ebrkon shum\u00eb m\u00eb pak burime p\u00ebr funksionimin e tij dhe, potencialisht, mund t\u00eb sh\u00ebrbej\u00eb m\u00eb shum\u00eb se nj\u00eb klas\u00eb.<\/p>\n<h4>Opsioni 3 \u2013 Faktori njer\u00ebzor<\/h4>\n<p>\nQashti fundit \u00ebsht\u00eb q\u00eb t\u00eb mbijetuarit vazhdojn\u00eb t\u00eb kryejn\u00eb \u00e7do sh\u00ebrbim q\u00eb ata tashm\u00eb po kryenin, por nuk fillojn\u00eb t\u00eb reja derisa problemet t\u00eb zgjidhin vet\u00eb (rikuperimi i rrjetit, ribashkimi i nj\u00eb nyje), ose nj\u00eb individ merr p\u00ebrgjegj\u00ebsin\u00eb p\u00ebr t\u00eb konfirmuar dorazi se pala tjet\u00ebr \u00ebsht\u00eb e vdekur.<\/p>\n<h4>Opsioni bonus<\/h4>\n<p>\nA e kam th\u00ebn\u00eb q\u00eb mund ta shtoni nj\u00eb nyje t\u00eb tret\u00eb?<\/p>\n<h2>Dy raft\u00eb<\/h2>\n<p>\nP\u00ebr q\u00ebllim argumenti, le t\u00eb imagjinojm\u00eb se ju kam bindur n\u00eb meritat e nyj\u00ebs s\u00eb tret\u00eb, tani duhet t\u00eb marrim n\u00eb konsiderat\u00eb vendndodhjen fizike t\u00eb nyjave. N\u00ebse ato jan\u00eb vendosur (dhe furnizohen me energji) n\u00eb t\u00eb nj\u00ebjtin raft, kjo gjithashtu paraqet nj\u00eb SPoF, dhe nj\u00eb q\u00eb nuk mund t\u00eb zgjidhet duke shtuar nj\u00eb raft t\u00eb dyt\u00eb.<\/p>\n<p>N\u00ebse kjo \u00ebsht\u00eb e habitshme, mendoni se \u00e7far\u00eb do t\u00eb ndodhte n\u00ebse rafti me dy nyje d\u00ebshton dhe si nyja e mbijetuar do ta dallonte k\u00ebt\u00eb rast nga d\u00ebshtimi i rrjetit.<\/p>\n<p>P\u00ebrgjigja e shkurt\u00ebr: kjo \u00ebsht\u00eb e pamundur, dhe ne p\u00ebrs\u00ebri kemi t\u00eb b\u00ebjm\u00eb me t\u00eb gjitha problemet e rastit me dy nyje. Ose mbijetuesi:<\/p>\n<ul>\n<li>injoron kuorumin dhe gabimisht p\u00ebrpiqet t\u00eb niste rikuperimin gjat\u00eb nd\u00ebrprerjeve t\u00eb rrjetit (mund\u00ebsia e p\u00ebrfundimit t\u00eb ndarjes \u2013 kjo \u00ebsht\u00eb nj\u00eb histori e ve\u00e7ant\u00eb dhe varet nga n\u00ebse PDU \u00ebsht\u00eb e angazhuar dhe ndajn\u00eb energjin\u00eb me ndonj\u00eb nga raftet), ose<\/li>\n<li>respekton kuorumin dhe shk\u00ebputet p\u00ebrpara kohe kur nyja e tij partnere d\u00ebshton<\/li>\n<\/ul>\n<p>\nN\u00eb \u00e7do rast, dy raft\u00eb nuk jan\u00eb m\u00eb t\u00eb mir\u00eb se nj\u00eb, dhe nyjat duhet ose t\u00eb marrin burime t\u00eb pavarura energjie, ose t\u00eb shp\u00ebrndahen n\u00eb tre (ose m\u00eb shum\u00eb, n\u00eb var\u00ebsi t\u00eb numrit t\u00eb nyjave q\u00eb keni) raft\u00eb.<\/p>\n<h3>Dy qendra t\u00eb t\u00eb dh\u00ebnave<\/h3>\n<p>\nN\u00eb k\u00ebt\u00eb pik\u00eb, lexuesit q\u00eb nuk jan\u00eb m\u00eb t\u00eb prir\u00eb p\u00ebr rrezik mund t\u00eb mendojn\u00eb p\u00ebr rikuperimin pas katastrof\u00ebs. \u00c7far\u00eb ndodh kur nj\u00eb asteroid godet nj\u00eb qend\u00ebr t\u00eb t\u00eb dh\u00ebnave me tre nyjat tona, t\u00eb shp\u00ebrndara n\u00eb tre raft\u00eb t\u00eb ndrysh\u00ebm? Sigurisht, ndodhin gj\u00ebra t\u00eb k\u00ebqija, por n\u00eb var\u00ebsi t\u00eb nevojave tuaja, shtimi i nj\u00eb qendre t\u00eb dyt\u00eb t\u00eb t\u00eb dh\u00ebnave mund t\u00eb jet\u00eb i pamjaftuesh\u00ebm.<\/p>\n<p>N\u00ebse gjith\u00e7ka \u00ebsht\u00eb b\u00ebr\u00eb si\u00e7 duhet, qendra e dyt\u00eb e t\u00eb dh\u00ebnave ju ofron (dhe kjo \u00ebsht\u00eb e arsyeshme) nj\u00eb kopje t\u00eb azhurnuar dhe t\u00eb sinkronizuar t\u00eb sh\u00ebrbimeve dhe t\u00eb dh\u00ebnave tuaja. Megjithat\u00eb, ashtu si n\u00eb skenar\u00ebt me dy nyje dhe dy raftet, sistemi nuk ka informacion t\u00eb mjaftuesh\u00ebm p\u00ebr t\u00eb siguruar disponueshm\u00ebrin\u00eb maksimale dhe p\u00ebr t\u00eb parandaluar d\u00ebmtimin (ose p\u00ebr\u00e7arjen e grupeve t\u00eb t\u00eb dh\u00ebnave). Edhe n\u00ebse ka tre nyje (ose rafte), shp\u00ebrndarja e tyre vet\u00ebm n\u00eb dy qendra t\u00eb t\u00eb dh\u00ebnave l\u00eb sistemin t\u00eb paaft\u00eb t\u00eb marr\u00eb nj\u00eb vendim t\u00eb sakt\u00eb n\u00eb rastin e nj\u00eb ngjarjeje (tani shum\u00eb m\u00eb t\u00eb mundshme) q\u00eb t\u00eb dy pal\u00ebt nuk mund ta lidhin.<\/p>\n<p>Kjo nuk do t\u00eb thot\u00eb se zgjidhja me dy qendra t\u00eb t\u00eb dh\u00ebnave nuk \u00ebsht\u00eb ndonj\u00ebher\u00eb e p\u00ebrshtatshme. Kompanit\u00eb shpesh d\u00ebshirojn\u00eb q\u00eb dikush t\u00eb jet\u00eb n\u00eb dijeni p\u00ebrpara se t\u00eb marr\u00eb nj\u00eb hap t\u00eb jasht\u00ebzakonsh\u00ebm n\u00eb procesin e kalimit n\u00eb qendr\u00ebn rezerv\u00eb t\u00eb t\u00eb dh\u00ebnave. Thjesht mbani parasysh se n\u00ebse d\u00ebshironi t\u00eb automatizoni d\u00ebshtimin, do t'ju duhej nj\u00eb qend\u00ebr e tret\u00eb e t\u00eb dh\u00ebnave q\u00eb kuorumi t\u00eb kishte kuptim (drejt p\u00ebr drejt ose p\u00ebrmes nj\u00eb arbitri), ose do t\u00eb duhet t\u00eb gjeni nj\u00eb m\u00ebnyr\u00eb p\u00ebr t\u00eb \u00e7aktivizuar n\u00eb m\u00ebnyr\u00eb t\u00eb besueshme t\u00ebr\u00eb qendr\u00ebn e t\u00eb dh\u00ebnave.<br \/>\n<br \/>Burimi: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/post\/494264\/\">habr.com<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u041f\u0440\u0438\u0432\u0435\u0442, \u0425\u0430\u0431\u0440! \u041f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u043b\u044f\u044e \u0432\u0430\u0448\u0435\u043c\u0443 \u0432\u043d\u0438\u043c\u0430\u043d\u0438\u044e \u043f\u0435\u0440\u0435\u0432\u043e\u0434 \u0441\u0442\u0430\u0442\u044c\u0438 \u00abTwo Nodes \u2014 The Devil is in the Details\u00bb \u0430\u0432\u0442\u043e\u0440\u0430 Andrew Beekhof. \u041c\u043d\u043e\u0433\u0438\u0435 \u043b\u044e\u0434\u0438 \u043f\u0440\u0435\u0434\u043f\u043e\u0447\u0438\u0442\u0430\u044e\u0442 \u043a\u043b\u0430\u0441\u0442\u0435\u0440\u044b \u0441\u043e\u0441\u0442\u043e\u044f\u0449\u0438\u0435 \u0438\u0437 \u0434\u0432\u0443\u0445 \u0443\u0437\u043b\u043e\u0432, \u043f\u043e\u0442\u043e\u043c\u0443 \u0447\u0442\u043e \u043e\u043d\u0438 \u043a\u0430\u0436\u0443\u0442\u0441\u044f \u043a\u043e\u043d\u0446\u0435\u043f\u0442\u0443\u0430\u043b\u044c\u043d\u043e \u0431\u043e\u043b\u0435\u0435 \u043f\u0440\u043e\u0441\u0442\u044b\u043c\u0438, \u043a\u0440\u043e\u043c\u0435 \u0442\u043e\u0433\u043e \u0435\u0449\u0435 \u0438 \u043d\u0430 33% \u0431\u043e\u043b\u0435\u0435 \u0434\u0435\u0448\u0435\u0432\u044b\u043c\u0438 \u0447\u0435\u043c \u0438\u0445 \u0442\u0440\u0435\u0445-\u0443\u0437\u043b\u043e\u0432\u044b\u0435 \u0441\u043e\u0431\u0440\u0430\u0442\u044c\u044f. \u0425\u043e\u0442\u044f \u0432\u043f\u043e\u043b\u043d\u0435 \u0440\u0435\u0430\u043b\u044c\u043d\u043e \u0441\u043e\u0431\u0440\u0430\u0442\u044c \u0445\u043e\u0440\u043e\u0448\u0438\u0439 \u043a\u043b\u0430\u0441\u0442\u0435\u0440 \u0438\u0437 \u0434\u0432\u0443\u0445 \u0443\u0437\u043b\u043e\u0432, [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-75726","post","type-post","status-publish","format-standard","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.2 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u041f\u0440\u0438\u0432\u0435\u0442, \u0425\u0430\u0431\u0440!\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" 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