{"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":"Klusteri me dy nod\u00eb - djalli \u00ebsht\u00eb n\u00eb detaje","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>P\u00ebrsh\u00ebndetje, Habr! Ju prezantoj p\u00ebrkthimin e artikullit <noindex><a rel=\"nofollow\" href=\"http:\/\/blog.clusterlabs.org\/blog\/2018\/two-node-problems\">\u00abDy Nodi \u2014 Djalli \u00ebsht\u00eb n\u00eb Detaje\u00bb<\/a><\/noindex> autor Andrew Beekhof.<\/p>\n<p>Shum\u00eb njer\u00ebz preferojn\u00eb klaster\u00ebt me dy node, sepse duken konceptualisht m\u00eb t\u00eb thjesht\u00eb, dhe gjithashtu jan\u00eb deri n\u00eb 33% m\u00eb t\u00eb lira se homolog\u00ebt e tyre me tre node. Megjithat\u00eb, \u00ebsht\u00eb krejt e mundur t\u00eb krijohet nj\u00eb klaster i mir\u00eb me dy node, por n\u00eb shumic\u00ebn e rasteve, p\u00ebr shkak t\u00eb skenar\u00ebve t\u00eb pap\u00ebrcaktuar, kjo konfigurim 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 p\u00ebr t\u00eb krijuar \u00e7do sistem t\u00eb lart\u00eb disponueshm\u00ebrie \u00ebsht\u00eb identifikimi dhe p\u00ebrpjekja p\u00ebr t\u00eb eliminuar pikat e vetme t\u00eb d\u00ebshtimit, shpesh t\u00eb shkurtra si <i>SPoF<\/i> (pik\u00eb e vetme d\u00ebshtimi).<\/p>\n<p>Duhet t\u00eb mbani parasysh se n\u00eb \u00e7do sistem \u00ebsht\u00eb e pamundur t\u00eb eliminohen t\u00eb gjitha rreziqet e mundshme t\u00eb ndalimit. Kjo rrjedh p\u00ebr t\u00eb pakt\u00ebn nga fakti se mbrojtja tipike kund\u00ebr rrezikut \u00ebsht\u00eb krijimi i nj\u00eb sasi t\u00eb caktuar t\u00eb tepric\u00ebs, e cila \u00e7on n\u00eb rritjen e kompleksitetit t\u00eb sistemit dhe shfaqjen e pikave t\u00eb reja t\u00eb d\u00ebshtimit. Prandaj, fillimisht shkojm\u00eb n\u00eb nj\u00eb kompromis dhe p\u00ebrqendrohemi n\u00eb ngjarjet q\u00eb lidhen me pikat e vetme t\u00eb d\u00ebshtimit, dhe jo n\u00eb zinxhir\u00ebt e ngjarjeve t\u00eb lidhura q\u00eb p\u00ebr k\u00ebt\u00eb arsye b\u00ebhen gjithnj\u00eb e m\u00eb pak t\u00eb mundura.<\/p>\n<p>Duke marr\u00eb parasysh kompromiset, ne jo vet\u00ebm q\u00eb k\u00ebrkojm\u00eb SPoF, por gjithashtu balancojm\u00eb rreziqet dhe pasojat, rezultati i t\u00eb cilave se \u00e7far\u00eb \u00ebsht\u00eb kritike dhe \u00e7far\u00eb jo mund t\u00eb ndryshoj\u00eb p\u00ebr \u00e7do zbatim.<\/p>\n<blockquote><p>Jo t\u00eb gjith\u00eb kan\u00eb nevoj\u00eb p\u00ebr furnizues alternativ\u00eb t\u00eb energjis\u00eb me linja t\u00eb pavarura t\u00eb energjis\u00eb. Megjith\u00ebse paranoia ka rezultuar e dobishme p\u00ebr t\u00eb pakt\u00ebn nj\u00eb klient, kur monitorimi i tyre zbuloi nj\u00eb transformator t\u00eb prishur. Klienti kishte telefonuar p\u00ebr t\u00eb paralajm\u00ebruar kompanin\u00eb e energjis\u00eb, derisa transformatori i prishur shp\u00ebrtheu.<\/p><\/blockquote>\n<p>\nNj\u00eb pik\u00eb fillimi natyrale \u00ebsht\u00eb q\u00eb sistemi t\u00eb ket\u00eb m\u00eb shum\u00eb se nj\u00eb node. Sidoqoft\u00eb, para se sistemi t\u00eb mund t\u00eb kaloj\u00eb sh\u00ebrbimet n\u00eb node-n q\u00eb mbetet pas nj\u00eb d\u00ebshtimi, n\u00eb p\u00ebrgjith\u00ebsi, duhet t\u00eb sigurohemi se sh\u00ebrbimet q\u00eb po kalohen nuk jan\u00eb aktive ndonj\u00eb ku tjet\u00ebr.<\/p>\n<p>Nj\u00eb klaster me dy node nuk ka disavantazhe, n\u00ebse si rezultat i d\u00ebshtimit t\u00eb dy node-t sh\u00ebrbejn\u00eb t\u00eb nj\u00ebjtin website statik. Sidoqoft\u00eb, t\u00eb gjitha ndryshojn\u00eb n\u00ebse t\u00eb dy an\u00ebt menaxhojn\u00eb pavarsisht nj\u00eb radh\u00eb t\u00eb p\u00ebrbashk\u00ebt t\u00eb pun\u00ebve ose ofrojn\u00eb qasje t\u00eb pa koordinuar p\u00ebr t\u00eb shkruar n\u00eb nj\u00eb databaz\u00eb t\u00eb replikosur ose n\u00eb nj\u00eb sistem t\u00eb p\u00ebrbashk\u00ebt skedari.<\/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 node \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, principi i ndarjes n\u00ebnkupton: a mund t\u00eb ndodh\u00eb q\u00eb nj\u00eb node konkuruese t\u00eb shkaktoj\u00eb d\u00ebmtimin e t\u00eb dh\u00ebnave? 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 nod\u00ebs nga k\u00ebrkesat hyr\u00ebse dhe nga ruajtja e q\u00ebndrueshme. Qasja m\u00eb e zakonshme p\u00ebr ndarjen \u00ebsht\u00eb shk\u00ebputja e node-ve t\u00eb prishura.<\/p>\n<p>Ka dy kategori metodash ndarjeje, t\u00eb cilat un\u00eb do t'i quaja <i>t\u00eb drejta<\/i> dhe <i>t\u00eb t\u00ebrthorta<\/i>, por gjithashtu i quajm\u00eb <i>aktive<\/i> dhe <i>pasive<\/i>. Metodat e drejta p\u00ebrfshijn\u00eb veprime nga node t\u00eb mbijetuar, si nd\u00ebrveprimi me pajisjet IPMI (Interfejsi i Menaxhimit t\u00eb Platform\u00ebs Inteligjente \u2014 interface p\u00ebr monitorimin dhe menaxhimin q\u00ebllim p\u00ebr gjendjen fizike t\u00eb serverit) ose iLO (mekanizmi i menaxhimit t\u00eb server\u00ebve pa akses fizik n\u00eb to), nd\u00ebrsa metodat e t\u00ebrthorta mb\u00ebshteten n\u00eb nod\u00ebn e d\u00ebshtuar p\u00ebr t\u00eb njohur ndonj\u00ebher\u00eb se ajo ndodhet n\u00eb nj\u00eb gjendje jo t\u00eb sh\u00ebndosh\u00eb (ose, t\u00eb pakt\u00ebn, pengon an\u00ebtar\u00ebt e tjer\u00eb n\u00eb rikuperim) dhe p\u00ebr t\u00eb sinjalizuar <noindex><a rel=\"nofollow\" href=\"https:\/\/en.wikipedia.org\/wiki\/Watchdog_timer\">watchdog harduare<\/a><\/noindex> n\u00eb lidhje me nevoj\u00ebn p\u00ebr t\u00eb shk\u00ebputur nod\u00ebn e prishur.<\/p>\n<p>Kvorumi ndihmon n\u00eb p\u00ebrdorimin e metodave si t\u00eb drejta ashtu edhe t\u00eb t\u00ebrthorta.<\/p>\n<h3>Ndarja e drejtp\u00ebrdrejt\u00eb<\/h3>\n<p>\nN\u00eb rastin e ndarjes s\u00eb drejtp\u00ebrdrejt\u00eb, ne mund t\u00eb p\u00ebrdorim kvorumin p\u00ebr t\u00eb parandaluar garat e ndarjes n\u00eb rastin e nj\u00eb d\u00ebshtimi t\u00eb rrjetit.<\/p>\n<p>Me konceptin e kvorumit, sistemi ka informacion t\u00eb mjaftuesh\u00ebm (edhe pa u lidhur me partner\u00ebt e tij) q\u00eb node-t automatikisht din\u00eb n\u00ebse duhet t\u00eb iniciat shk\u00ebputjen dhe \/ ose rikuperimin.<\/p>\n<p>Pa kvorum, t\u00eb dy an\u00ebt e ndarjes s\u00eb rrjetit do t\u00eb supozonin drejt p\u00ebr drejt se ana tjet\u00ebr \u00ebsht\u00eb e vdekur, dhe do t\u00eb p\u00ebrpiqeshin p\u00ebr t\u00eb shk\u00ebputur tjetrin. N\u00eb skenarin m\u00eb t\u00eb keq, t\u00eb dy an\u00ebt do t\u00eb arrijn\u00eb t\u00eb shk\u00ebputin t\u00eb gjith\u00eb klasterin. Nj\u00eb skenar alternativ \u00ebsht\u00eb deathmatch, nj\u00eb cik\u00ebl t\u00eb pafund t\u00eb node-ve q\u00eb shfaqen, nuk shohin peer-in e tyre, i rihapin ata dhe nisin rikuperimin vet\u00ebm p\u00ebr t\u00eb u rihapur, kur peer-i i tyre kalon p\u00ebrmes s\u00eb nj\u00ebjt\u00ebs logjik\u00eb.<\/p>\n<p>Problemi me ndarjen ka t\u00eb b\u00ebj\u00eb me faktin se pajisat m\u00eb t\u00eb p\u00ebrdorura b\u00ebhen t\u00eb paaksesueshme p\u00ebr shkak t\u00eb t\u00eb nj\u00ebjtave ngjarje d\u00ebshtimi, n\u00eb t\u00eb cilat ne d\u00ebshirojm\u00eb t\u00eb p\u00ebrqendrohemi p\u00ebr rikuperim. Shumica e kartave IPMI dhe iLO jan\u00eb instaluar n\u00eb hostet q\u00eb ato kontrollojn\u00eb dhe, nga e drejta, p\u00ebrdorin t\u00eb nj\u00ebjt\u00ebn rrjet\u00eb, duke b\u00ebr\u00eb q\u00eb node-t e synuara t\u00eb supozojn\u00eb se node-t 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 t\u00ebrthort\u00eb<\/h3>\n<p>\nKvorumi \u00ebsht\u00eb gjithashtu i r\u00ebnd\u00ebsish\u00ebm p\u00ebr menaxhimin e ndarjeve t\u00eb t\u00ebrthorta; n\u00ebse gjith\u00e7ka b\u00ebhet si\u00e7 duhet, kvorumi mund t\u00eb lejoj\u00eb mbeturinat t\u00eb supozojn\u00eb q\u00eb node-t e humbura pas nj\u00eb periudhe t\u00eb caktuar kalojn\u00eb n\u00eb nj\u00eb gjendje t\u00eb sigurt.<\/p>\n<p>Me nj\u00eb konfigurim t\u00eb till\u00eb, timeri i watchdog hardware rikthehet \u00e7do N sekonda, n\u00ebse kvorumi nuk \u00ebsht\u00eb humbur. N\u00ebse timeri (zakonisht disa her\u00eb N) skadon, pajisja kryen nj\u00eb fikje t\u00eb pap\u00ebrshtatshme (nuk b\u00ebn shutdown).<\/p>\n<p>Ky qasje \u00ebsht\u00eb shum\u00eb efektive, por pa kvorum p\u00ebr menaxhimin e tij, ka pak informacion brenda klasterit. Nuk \u00ebsht\u00eb e leht\u00eb t\u00eb p\u00ebrcaktohet dallimi mes nd\u00ebrprerjes s\u00eb rrjetit dhe d\u00ebshtimit t\u00eb node-t partner. Arsyetimi p\u00ebrse ky fakt ka r\u00ebnd\u00ebsi \u00ebsht\u00eb se pa aft\u00ebsin\u00eb p\u00ebr t\u00eb dalluar k\u00ebto dy raste, ju detyroheni t\u00eb zgjidhni t\u00eb nj\u00ebjt\u00ebn m\u00ebnyr\u00eb veprimi p\u00ebr t\u00eb dy rastet.<\/p>\n<p>Problemi me zgjedhjen e nj\u00eb m\u00ebnyre veprimi \u00ebsht\u00eb se nuk ekziston nj\u00eb m\u00ebnyr\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 node partner \u00ebsht\u00eb aktiv, por n\u00eb t\u00eb v\u00ebrtet\u00eb ka ndodhur nj\u00eb d\u00ebshtim, klasteri do t\u00eb ndal\u00eb tep\u00ebr sh\u00ebrbimet q\u00eb duhet t\u00eb ishin duke funksionuar p\u00ebr t\u00eb kompensuar humbjen e sh\u00ebrbimeve t\u00eb node partner t\u00eb r\u00ebn\u00eb.<\/li>\n<li>N\u00ebse vendosni t\u00eb supozoni se node nuk funksionon, por ishte thjesht nj\u00eb d\u00ebshtim i rrjetit dhe n\u00eb t\u00eb v\u00ebrtet\u00eb node i larg\u00ebt funksionon, at\u00ebher\u00eb, n\u00eb m\u00eb t\u00eb mir\u00ebn, ju pajtoheni me nj\u00eb rivler\u00ebsim manual t\u00eb grupeve t\u00eb t\u00eb dh\u00ebnave q\u00eb do t\u00eb rezultojn\u00eb.<\/li>\n<\/ul>\n<p>\nPavar\u00ebsisht nga heuristika q\u00eb p\u00ebrdorni, \u00ebsht\u00eb triviale t\u00eb krijoni nj\u00eb d\u00ebshtim q\u00eb ose do t\u00eb b\u00ebj\u00eb q\u00eb t\u00eb dy pal\u00ebt t\u00eb funksionojn\u00eb, ose do t\u00eb detyroj\u00eb klasterin t\u00eb \u00e7aktivizoj\u00eb node-t e mbetura. Mospranimi i kvorumit v\u00ebrtet i privon klasterin nga nj\u00eb nga mjetet m\u00eb t\u00eb fuqishme n\u00eb arsenalin e saj.<\/p>\n<p>N\u00ebse nuk ka nj\u00eb alternativ\u00eb tjet\u00ebr, qasja m\u00eb e mir\u00eb do t\u00eb ishte t\u00eb sakrifikoni disponueshm\u00ebrin\u00eb (k\u00ebtu autori referohet te teorema CAP). Disponueshm\u00ebria e lart\u00eb e t\u00eb dh\u00ebnave t\u00eb d\u00ebmtuara nuk ndihmon ask\u00ebnd, dhe rivler\u00ebsimi manual i grupeve t\u00eb ndryshme t\u00eb t\u00eb dh\u00ebnave gjithashtu nuk \u00ebsht\u00eb k\u00ebnaq\u00ebsues.<\/p>\n<h2>Kvorumi<\/h2>\n<p>\nKvorumi ting\u00ebllon bukur, a po?<\/p>\n<p>E vetmja penges\u00eb \u00ebsht\u00eb se p\u00ebr t\u00eb pasur kvorum n\u00eb nj\u00eb klaster me N an\u00ebtar\u00eb, ju nevojitet q\u00eb t\u00eb ket\u00eb ende nj\u00eb lidhje mes N \/ 2 + 1 t\u00eb node-ve tuaj. Kjo \u00ebsht\u00eb e pamundur n\u00eb nj\u00eb klaster me dy node pas nj\u00eb d\u00ebshtimi t\u00eb nj\u00eb node.<\/p>\n<p>\u00c7ka na \u00e7on n\u00eb problemin themelor me dy node:<br \/>\nkvorumi nuk ka kuptim n\u00eb klasterat me dy node, dhe pa t\u00eb, \u00ebsht\u00eb e pamundur t\u00eb p\u00ebrcaktohet me besueshm\u00ebri nj\u00eb kurs veprimi q\u00eb maksimizon disponueshm\u00ebrin\u00eb dhe parandalon humbjen e t\u00eb dh\u00ebnave.<br \/>\nMadje edhe n\u00eb nj\u00eb sistem me dy node, t\u00eb lidhura me nj\u00eb kabllo kryq\u00ebzimi, \u00ebsht\u00eb e pamundur t\u00eb krihet me siguri dallimi mes nd\u00ebrprerjes s\u00eb rrjetit dhe d\u00ebshtimit t\u00eb nj\u00eb node tjet\u00ebr. Nd\u00ebrprerja e nj\u00eb skaji (probabiliteti i t\u00eb cilit \u00ebsht\u00eb ndoshta proporcional me distanc\u00ebn mes node-ve) do t\u00eb ishte e mjaftueshme p\u00ebr t\u00eb hedhur posht\u00eb \u00e7do supozim se funksionaliteti i kanalit \u00ebsht\u00eb i barabart\u00eb me sh\u00ebndetin e node partner.<\/p>\n<h3>T\u00eb b\u00ebjm\u00eb q\u00eb klasteri i dy node-ve t\u00eb funksionoj\u00eb<\/h3>\n<p>\nNganj\u00ebher\u00eb klienti nuk mund ose nuk d\u00ebshiron t\u00eb blej\u00eb nj\u00eb node t\u00eb tret\u00eb, dhe ne detyrohemi t\u00eb k\u00ebrkojm\u00eb nj\u00eb alternativ\u00eb.<\/p>\n<h4>Zgjidhja 1 - Metoda e dyfishimit t\u00eb ndarjes<\/h4>\n<p>\nPajisja iLO ose IPMI e node-t \u00ebsht\u00eb nj\u00eb pik\u00eb d\u00ebshtimi, sepse, n\u00eb rast d\u00ebshtimi, ato q\u00eb mbeten nuk mund ta p\u00ebrdorin at\u00eb p\u00ebr t\u00eb transferuar node-n n\u00eb nj\u00eb gjendje t\u00eb sigurt. N\u00eb nj\u00eb klaster me 3 ose m\u00eb shum\u00eb node, ne mund ta leht\u00ebsojm\u00eb k\u00ebt\u00eb duke llogaritur kvorumin dhe duke p\u00ebrdorur watchdog hardware (mekanizem ndarjeje t\u00eb t\u00ebrthort\u00eb, si\u00e7 u diskutua m\u00eb par\u00eb). N\u00eb rastin e dy node, ne duhet t\u00eb p\u00ebrdorim nd\u00ebrrues t\u00eb energjis\u00eb (pjes\u00eb t\u00eb shp\u00ebrndarjes s\u00eb energjis\u00eb ose PDU).<\/p>\n<p>Pas d\u00ebshtimit, ai q\u00eb mbetet p\u00ebrpiqet fillimisht t\u00eb lidhet me pajisjen kryesore t\u00eb ndarjes (iLO ose IPMI t\u00eb integruar). N\u00ebse kjo \u00ebsht\u00eb e suksesshme, rikuperimi vazhdon si zakonisht. Vet\u00ebm n\u00eb rast d\u00ebshtimi t\u00eb pajisjes iLO\/IPMI, lidhemi me PDU, n\u00ebse lidhja \u00ebsht\u00eb e suksesshme, rikuperimi mund t\u00eb vazhdoj\u00eb.<\/p>\n<p>Sigurohuni t\u00eb vendosni PDU-n\u00eb n\u00eb nj\u00eb rrjet t\u00eb ndrysh\u00ebm nga trafiku i grumbullit, 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 \u00ebsht\u00eb PDU nj\u00eb pik\u00eb e vetme d\u00ebshtimi? P\u00ebrgjigjja \u00ebsht\u00eb sigurisht q\u00eb po.<\/p>\n<p>N\u00ebse ky rrezik \u00ebsht\u00eb i r\u00ebnd\u00ebsish\u00ebm p\u00ebr ju - nuk jeni vet\u00ebm: lidhni t\u00eb dy nj\u00ebsit\u00eb me dy PDU dhe tregoni softuerit t\u00eb grumbullit t\u00eb p\u00ebrdor\u00eb t\u00eb dyja kur ndizni ose fikni nj\u00ebsit\u00eb. Tani grumbulli mbetet aktiv n\u00ebse nj\u00eb PDU d\u00ebshton, dhe p\u00ebr t\u00eb bllokuar rikuperimin \u00ebsht\u00eb e nevojshme nj\u00eb d\u00ebshtim i dyt\u00eb, qoft\u00eb nga PDU tjet\u00ebr apo nga pajisja IPMI.<\/p>\n<h4>Mund\u00ebsia 2 - Shtimi i nj\u00eb arbitri<\/h4>\n<p>\nN\u00eb disa skenar\u00eb, megjith\u00ebse metoda e ndarjes s\u00eb dyfisht\u00eb \u00ebsht\u00eb teknikisht e mundur, ajo \u00ebsht\u00eb politikisht e komplikuar. Shum\u00eb kompani preferojn\u00eb t\u00eb ken\u00eb nj\u00eb ndarje t\u00eb qart\u00eb midis administrat\u00ebve dhe pronar\u00ebve t\u00eb aplikacioneve, dhe administrator\u00ebt e rrjetit q\u00eb angazhohen p\u00ebr sigurin\u00eb nuk jan\u00eb gjithmon\u00eb entuziast\u00eb p\u00ebr t\u00eb dh\u00ebn\u00eb askujt parametrat e aksesit n\u00eb PDU.<\/p>\n<p>N\u00eb k\u00ebt\u00eb rast, alternativa e rekomanduar \u00ebsht\u00eb krijimi i nj\u00eb pal\u00eb t\u00eb tret\u00eb neutrale, e cila mund t\u00eb plot\u00ebsoj\u00eb llogaritjen e kuorumit.<\/p>\n<p>N\u00eb rast d\u00ebshtimi, nj\u00ebsi duhet t\u00eb ket\u00eb mund\u00ebsin\u00eb t\u00eb shoh\u00eb eterin e partnerit t\u00eb saj ose t\u00eb arbitrit p\u00ebr t\u00eb rikuperuar sh\u00ebrbimet. Arbitri gjithashtu p\u00ebrfshin nj\u00eb funksion shk\u00ebputjeje n\u00ebse t\u00eb dy nj\u00ebsit\u00eb mund t\u00eb shohin arbitrin, por nuk shohin nj\u00ebri-tjetrin.<\/p>\n<p>Kjo mund\u00ebsi duhet t\u00eb p\u00ebrdoret n\u00eb \u00e7ift me nj\u00eb metod\u00eb t\u00eb t\u00ebrthort\u00eb ndarjeje, si nj\u00eb timer hardware watchdog, i cili \u00ebsht\u00eb i vendosur p\u00ebr t\u00eb fikur makin\u00ebn n\u00ebse humbet lidhjen me nj\u00ebsin\u00eb e saj partnere dhe arbitrin. N\u00eb k\u00ebt\u00eb m\u00ebnyr\u00eb, i mbijetuar mund t\u00eb supozoj\u00eb me mjaft siguri se nj\u00ebsia e tij partnere do t\u00eb jet\u00eb n\u00eb nj\u00eb gjendje t\u00eb sigurt pas skadimit t\u00eb.timer-it hardware watchdog.<\/p>\n<p>Dallimi praktik midis arbitrit dhe nj\u00ebsis\u00eb s\u00eb tret\u00eb \u00ebsht\u00eb se arbitri k\u00ebrkon shum\u00eb m\u00eb pak burime p\u00ebr t\u00eb funksionuar dhe, potencialisht, mund t\u00eb sh\u00ebrbej\u00eb m\u00eb shum\u00eb se nj\u00eb grumbull.<\/p>\n<h4>Mund\u00ebsia 3 - Faktori Njer\u00ebzor<\/h4>\n<p>\nQasja e fundit \u00ebsht\u00eb q\u00eb t\u00eb mbijetuarit t\u00eb vazhdojn\u00eb t\u00eb kryejn\u00eb \u00e7do sh\u00ebrbim q\u00eb ata tashm\u00eb po kryenin, por t\u00eb mos fillojn\u00eb t\u00eb reja, derisa ose problemi t\u00eb zgjidhet vetvetiu (rikuperimi i rrjetit, ri-dizanje i nj\u00ebsis\u00eb), ose nj\u00eb njeri t\u00eb marr\u00eb p\u00ebrsip\u00ebr p\u00ebrgjegj\u00ebsin\u00eb p\u00ebr t\u00eb konfirmuar manualisht q\u00eb pala tjet\u00ebr \u00ebsht\u00eb e vdekur.<\/p>\n<h4>Mund\u00ebsi Bonus<\/h4>\n<p>\nA kam th\u00ebn\u00eb se mund t\u00eb shtoni nj\u00eb nj\u00ebsi t\u00eb tret\u00eb?<\/p>\n<h2>Dy shtylla<\/h2>\n<p>\nP\u00ebr argumentin, le t\u00eb supozojm\u00eb se ju kam bindur p\u00ebr p\u00ebrfitimet e nj\u00eb nj\u00ebsie t\u00eb tret\u00eb, tani ne duhet t\u00eb shqyrtojm\u00eb vendndodhjen fizike t\u00eb nj\u00ebsive. N\u00ebse ato jan\u00eb vendosur (dhe marrin energji) n\u00eb t\u00eb nj\u00ebjtin raf, kjo gjithashtu paraqet nj\u00eb SPoF, dhe nj\u00eb t\u00eb till\u00eb q\u00eb nuk mund t\u00eb zgjidhet duke shtuar nj\u00eb raf t\u00eb dyt\u00eb.<\/p>\n<p>N\u00ebse kjo \u00ebsht\u00eb befasuese, mendoni se \u00e7far\u00eb do t\u00eb ndodhte n\u00ebse raf  me dy nj\u00ebsit\u00eb d\u00ebshton, dhe si nj\u00ebsia mbijetuar do t\u00eb dallonte k\u00ebt\u00eb rast nga nj\u00eb d\u00ebshtim n\u00eb rrjet.<\/p>\n<p>P\u00ebrgjigjja e shkurt\u00ebr: \u00ebsht\u00eb e pamundur, dhe ne p\u00ebrs\u00ebri kemi t\u00eb gjitha problemet q\u00eb vijn\u00eb me dy nj\u00ebsit\u00eb. Ose i mbijetuari:<\/p>\n<ul>\n<li>injoron kuorum dhe p\u00ebrpiqet gabim t\u00eb inicioj\u00eb rikuperimin gjat\u00eb nd\u00ebrprerjeve t\u00eb rrjetit (mund\u00ebsia p\u00ebr t\u00eb p\u00ebrfunduar ndarjen \u00ebsht\u00eb nj\u00eb histori tjet\u00ebr dhe varet n\u00ebse PDU \u00ebsht\u00eb i angazhuar dhe ndajn\u00eb energjin\u00eb me ndonj\u00eb nga rafet), ose<\/li>\n<li>respekton kuorum dhe shk\u00ebputet para kohe, kur nj\u00ebsia e saj partnere d\u00ebshtin.<\/li>\n<\/ul>\n<p>\nN\u00eb \u00e7do rast, dy rafet nuk jan\u00eb m\u00eb t\u00eb mira se nj\u00eb, dhe nj\u00ebsit\u00eb duhet t\u00eb marrin ose burime t\u00eb pavarura energjie, ose t\u00eb shp\u00ebrndahen p\u00ebr tre (ose m\u00eb shum\u00eb, var\u00ebsisht nga sa nj\u00ebsi keni) rafet.<\/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 prirur ndaj rrezikut mund t\u00eb mendojn\u00eb p\u00ebr rikuperimin pas nj\u00eb katastrofe. \u00c7far\u00eb ndodh kur nj\u00eb asteroid p\u00ebrfundon n\u00eb nj\u00eb qend\u00ebr t\u00eb dh\u00ebnash me tre nj\u00ebsit\u00eb tona, t\u00eb shp\u00ebrndara n\u00eb tre rafet t\u00eb ndryshme? \u00cbsht\u00eb e qart\u00eb q\u00eb S\u00eb Keqes do t\u00eb ndodhin, 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 e pamjaftueshme.<\/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 \u00ebsht\u00eb e arsyeshme) nj\u00eb kopje t\u00eb azhurnuar dhe t\u00eb konfirmuar t\u00eb sh\u00ebrbimeve tuaja dhe t\u00eb dh\u00ebnave t\u00eb tyre. Megjithat\u00eb, si\u00e7 ndodh n\u00eb skenar\u00ebt me dy nyje dhe dy rafts, sistemi nuk ka informacion t\u00eb mjaftuesh\u00ebm p\u00ebr t\u00eb garantuar 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 me pranin\u00eb e tre nyjeve (ose rafteve), shp\u00ebrndarja e tyre vet\u00ebm n\u00eb dy qendra t\u00eb t\u00eb dh\u00ebnave e l\u00eb sistemin pa aft\u00ebsin\u00eb p\u00ebr t\u00eb marr\u00eb vendimin e duhur n\u00eb rastin e nj\u00eb (ndoshta shum\u00eb m\u00eb t\u00eb mundsh\u00ebm) ngjarjeje, t\u00eb cil\u00ebn t\u00eb dy an\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 e p\u00ebrshtatshme. Kompanit\u00eb shpesh duan q\u00eb dikush t\u00eb jet\u00eb n\u00eb dijeni p\u00ebrpara se t\u00eb nd\u00ebrmarr\u00eb nj\u00eb hap t\u00eb jasht\u00ebzakonsh\u00ebm p\u00ebr t\u00eb kaluar n\u00eb qendr\u00ebn e dyt\u00eb t\u00eb rezerv\u00ebs. Thjesht mbani mend se n\u00ebse d\u00ebshironi t\u00eb automatizoni d\u00ebshtimin, do t\u2019ju nevojitet ose nj\u00eb qend\u00ebr e tret\u00eb e t\u00eb dh\u00ebnave p\u00ebr t\u00eb b\u00ebr\u00eb kuorumin t\u00eb ket\u00eb kuptim (drejtp\u00ebrdrejt ose p\u00ebrmes nj\u00eb arbitri), ose do t\u00eb duhet t\u00eb gjeni nj\u00eb m\u00ebnyr\u00eb p\u00ebr t\u00eb shk\u00ebputur n\u00eb m\u00ebnyr\u00eb t\u00eb sigurt t\u00eb gjith\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 5.0.0.1 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u041f\u0440\u0438\u0432\u0435\u0442, 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