{"id":5494,"date":"2026-06-15T14:01:13","date_gmt":"2026-06-15T14:01:13","guid":{"rendered":"https:\/\/cloudsave.app\/?p=5494"},"modified":"2026-06-15T16:02:23","modified_gmt":"2026-06-15T16:02:23","slug":"kod%c4%97l-vm-momentin%c4%97s-kopijos-n%c4%97ra-saugios-operacij%c5%b3-duomen%c5%b3-baz%c4%97ms-dba-vadovas-duomen%c5%b3-vientisumui-u%c5%betikrinti","status":"publish","type":"post","link":"https:\/\/cloudsave.app\/lt\/knowledge-base\/kod%c4%97l-vm-momentin%c4%97s-kopijos-n%c4%97ra-saugios-operacij%c5%b3-duomen%c5%b3-baz%c4%97ms-dba-vadovas-duomen%c5%b3-vientisumui-u%c5%betikrinti\/","title":{"rendered":"Kod\u0117l VM momentin\u0117s kopijos n\u0117ra saugios operacij\u0173 duomen\u0173 baz\u0117ms: DBA vadovas duomen\u0173 vientisumui u\u017etikrinti"},"content":{"rendered":"<p>DevOps in\u017einieriams ir sistem\u0173 administratoriams virtuali\u0173j\u0173 ma\u0161in\u0173 (VM) momentin\u0117s kopijos (angl. snapshots) yra pamatinis \u012frankis. Jos suteikia greit\u0105 ir patog\u0173 b\u016bd\u0105 u\u017efiksuoti serverio b\u016bsen\u0105 prie\u0161 riziking\u0105 pataisym\u0105, didel\u012f konfig\u016bracijos pakeitim\u0105 ar programos diegim\u0105. Jei kas nors nepavyksta, sugr\u0105\u017einimas \u012f ankstesn\u0119 b\u016bsen\u0105 u\u017etrunka vos kelias sekundes.<\/p>\n<p>Ta\u010diau, kai \u0161i metodika taikoma transakcin\u0117ms duomen\u0173 baz\u0117ms \u2013 tokioms kaip \u201ePostgreSQL\u201c, \u201eMySQL\u201c, \u201eOracle\u201c ar \u201eMicrosoft SQL Server\u201c \u2013 VM momentin\u0117s kopijos i\u0161 saugumo priemon\u0117s virsta tiksin\u010dia bomba.<\/p>\n<p>Pasikliovimas standartin\u0117mis hipervizoriaus momentin\u0117mis kopijomis darant duomen\u0173 bazi\u0173 atsargines kopijas yra viena da\u017eniausi\u0173 duomen\u0173 sugadinimo, \u201eply\u0161usi\u0173 puslapi\u0173\u201c (angl. torn pages) ir neatkuriam\u0173 gamybini\u0173 sistem\u0173 prastov\u0173 prie\u017eas\u010di\u0173. \u0160iame straipsnyje aptarsime architekt\u016brin\u012f konflikt\u0105 tarp hipervizori\u0173 ir duomen\u0173 bazi\u0173 varikli\u0173, duomen\u0173 sugadinimo mechanik\u0105 kuriant momentines kopijas bei in\u017einerin\u0119 praktik\u0105, b\u016btin\u0105 saugiam virtualizuot\u0173 duomen\u0173 bazi\u0173 atsargini\u0173 kopij\u0173 k\u016brimui.<\/p>\n<h2>Architekt\u016brinis konfliktas: hipervizoriai prie\u0161 duomen\u0173 bazi\u0173 variklius<\/h2>\n<p>Norint suprasti, kod\u0117l VM momentin\u0117s kopijos kelia pavoj\u0173 duomen\u0173 baz\u0117ms, pirmiausia turime i\u0161nagrin\u0117ti, kaip abi sistemos valdo b\u016bsen\u0105 ir I\/O (\u012fvesties\/i\u0161vesties) operacijas.<\/p>\n<h3>Kaip hipervizoriai atlieka momentines kopijas<\/h3>\n<p>Kai hipervizorius (pvz., \u201eVMware ESXi\u201c, \u201eMicrosoft Hyper-V\u201c arba KVM) sukuria momentin\u0119 kopij\u0105, jis nekopijuoja viso disko. Vietoj to, jis u\u017e\u0161aldo esam\u0105 virtualaus disko fail\u0105 (pvz., <code>.vmdk<\/code> arba <code>.vhdx<\/code>) \u012f tik skaitymo b\u016bsen\u0105 ir sukuria nauj\u0105 \u201edelta\u201c disk\u0105 (skirtum\u0173 disk\u0105). Visi v\u0117lesni \u012fra\u0161ymo veiksmai nukreipiami \u012f \u0161\u012f \u201edelta\u201c disk\u0105.<\/p>\n<p>Kai momentin\u0117 kopija i\u0161trinama, hipervizorius turi \u012fra\u0161yti (konsoliduoti) duomenis i\u0161 \u201edelta\u201c disko atgal \u012f pagrindin\u012f disk\u0105. Standartin\u0117s momentin\u0117s kopijos visi\u0161kai \u201ene\u017eino\u201c apie sve\u010dio operacin\u0117je sistemoje veikian\u010dias programas. Jos u\u017efiksuoja disko b\u016bsen\u0105 tiksliai toki\u0105, kokia ji yra t\u0105 mikrosekund\u0119.<\/p>\n<h3>Kaip transakcin\u0117s duomen\u0173 baz\u0117s valdo b\u016bsen\u0105<\/h3>\n<p>Transakcin\u0117s duomen\u0173 baz\u0117s yra sukurtos remiantis ACID savyb\u0117mis (atomumas, nuoseklumas, izoliacija, patvarumas). Siekiant u\u017etikrinti auk\u0161t\u0105 na\u0161um\u0105 ir kartu i\u0161laikyti ACID atitikt\u012f, duomen\u0173 baz\u0117s ne visada i\u0161kart \u012fra\u0161o kiekvien\u0105 transakcij\u0105 tiesiai \u012f pagrindinius duomen\u0173 failus diske. Vietoj to jos naudoja sud\u0117ting\u0105, keli\u0173 pakop\u0173 architekt\u016br\u0105:<\/p>\n<ol>\n<li><strong>Buferio fondas \/ bendrinami buferiai:<\/strong> duomenys nuskaitomi ir modifikuojami sistemos atmintyje.<\/li>\n<li><strong>\u012era\u0161ymo \u017eurnalas (WAL) \/ \u201eRedo\u201c \u017eurnalai:<\/strong> pakeitimai nuosekliai \u012fra\u0161omi \u012f itin optimizuot\u0105 \u017eurnalo fail\u0105 diske, kad b\u016bt\u0173 u\u017etikrintas patvarumas.<\/li>\n<li><strong>Kontroliniai ta\u0161kai \/ \u201eLazy Writers\u201c:<\/strong> periodi\u0161kai duomen\u0173 baz\u0117 i\u0161 atminties \u012f tikruosius duomen\u0173 failus diske perkelia modifikuotus (\u201ene\u0161varius\u201c) puslapius.<\/li>\n<\/ol>\n<p>D\u0117l \u0161ios architekt\u016bros fiziniai duomen\u0173 failai diske beveik visada nesutampa su tikr\u0105ja duomen\u0173 baz\u0117s b\u016bsena. Tikroji duomen\u0173 baz\u0117s b\u016bsena egzistuoja tik kaip duomen\u0173 fail\u0173 diske, WAL\/\u201eRedo\u201c \u017eurnal\u0173 ir \u0161iuo metu atmintyje esan\u010di\u0173 duomen\u0173 derinys.<\/p>\n<h2>Pavojinga zona: kas vyksta kuriant VM momentin\u0119 kopij\u0105<\/h2>\n<p>Kai kuriate standartin\u0119 VM momentin\u0119 kopij\u0105 duomen\u0173 baz\u0117s serveryje, u\u017efiksuojate <strong>nuosekli\u0105 avarijos atveju<\/strong> (angl. crash-consistent) b\u016bsen\u0105.<\/p>\n<h3>Nuoseklumas avarijos atveju prie\u0161 nuoseklum\u0105 programos lygiu<\/h3>\n<p>Nuosekli avarijos atveju momentin\u0117 kopija prilygsta maitinimo laido i\u0161traukimui i\u0161 fizinio serverio. Disko b\u016bsena u\u017efiksuojama, ta\u010diau tai, kas buvo atmintyje, prarandama, o tai, kas buvo pakeliui \u012f saugojimo valdikl\u012f, staiga nutraukiama.<\/p>\n<p>Nors \u0161iuolaikin\u0117s duomen\u0173 baz\u0117s yra sukurtos taip, kad atsigaut\u0173 po netik\u0117to maitinimo praradimo per\u017eaisdamos \u012fra\u0161ymo \u017eurnal\u0105 (WAL), pasikliauti avarijos atk\u016brimu kaip pagrindine atsargini\u0173 kopij\u0173 strategija yra labai pavojinga. Jei j\u016bs\u0173 duomen\u0173 baz\u0117 apima kelis virtualius diskus (pvz., duomen\u0173 failai <code>D:<\/code> diske, o WAL \u2013 <code>E:<\/code> diske), hipervizorius gali nepadaryti abiej\u0173 disk\u0173 momentin\u0117s kopijos t\u0105 pa\u010di\u0105 mikrosekund\u0119. Jei WAL disko momentin\u0117 kopija u\u017efiksuojama bent sekund\u0117s dalimi v\u0117liau nei duomen\u0173 disko, atk\u016brimo metu duomen\u0173 baz\u0117 negali suderinti sekos numeri\u0173, tod\u0117l \u012fvyksta lemtinga korupcija.<\/p>\n<h3>\u201eVM Stun\u201c efektas didelio transakcij\u0173 skai\u010diaus sistemose<\/h3>\n<p>Momentin\u0117s kopijos k\u016brimo procesas \u2013 ir, dar svarbiau, jos konsolidavimo procesas \u2013 sukelia rei\u0161kin\u012f, vadinam\u0105 \u201eVM Stun\u201c (virtualios ma\u0161inos sustingimu).<\/p>\n<p>Kad saugiai perjungt\u0173 I\/O i\u0161 pagrindinio disko \u012f \u201edelta\u201c disk\u0105, hipervizorius turi trumpam pristabdyti (sustingdyti) virtuali\u0105 ma\u0161in\u0105. Lengvai apkrautam \u017einiatinklio serveriui \u0161is sustingimas gali trukti 10\u201350 milisekund\u017ei\u0173 ir likti nepasteb\u0117tas. Ta\u010diau duomen\u0173 bazei su dideliu I\/O srautu didelio \u201edelta\u201c disko konsolidavimas gali sustingdyti VM kelioms sekund\u0117ms.<\/p>\n<p>VM sustingimo metu:<br \/>\n* Nutr\u016bksta tinklo ry\u0161iai, tod\u0117l programos patiria skirt\u0105j\u012f laik\u0105 (timeout).<br \/>\n* Didelio pasiekiamumo klasteriai (pvz., \u201eSQL Server Always On\u201c, \u201ePostgreSQL Patroni\u201c ar \u201eMySQL Galera\u201c) praleid\u017eia \u201e\u0161irdies plakimo\u201c (heartbeat) patikras.<br \/>\n* Klasteris gali nuspr\u0119sti, kad susting\u0119s mazgas yra negyvas, ir inicijuoti nereikaling\u0105 bei trikdan\u010di\u0105 perjungim\u0105 (angl. failover) (vadinamasis \u201esplit-brain\u201c scenarijus).<\/p>\n<h3>\u201ePly\u0161\u0119 puslapiai\u201c ir I\/O nesuderinamumas<\/h3>\n<p>Duomen\u0173 bazi\u0173 varikliai paprastai ra\u0161o duomenis tam tikro dyd\u017eio puslapiais (pvz., 8 KB \u201ePostgreSQL\u201c ir \u201eSQL Server\u201c, 16 KB \u201eInnoDB\u201c). Ta\u010diau pagrindin\u0117 operacin\u0117 sistema ir saugojimo masyvai apdoroja I\/O ma\u017eesniais blokais (pvz., 4 KB arba 512 bait\u0173).<\/p>\n<p>Jei hipervizorius sukuria momentin\u0119 kopij\u0105 tiksliai tuo metu, kai duomen\u0173 baz\u0117 ra\u0161o 8 KB puslap\u012f, momentin\u0117 kopija gali u\u017efiksuoti pirmuosius 4 KB nauj\u0173 duomen\u0173 ir paskutinius 4 KB sen\u0173 duomen\u0173. Tai sukuria <strong>\u201eply\u0161us\u012f puslap\u012f\u201c<\/strong>. Bandant atkurti momentin\u0119 kopij\u0105, duomen\u0173 baz\u0117 perskaitys puslap\u012f, nepraeis kontrolin\u0117s sumos patikros ir pa\u017eym\u0117s duomen\u0173 baz\u0119 kaip sugadint\u0105.<\/p>\n<h2>Realaus pasaulio pasekm\u0117s konkretiems duomen\u0173 bazi\u0173 varikliams<\/h2>\n<p>Skirtingi duomen\u0173 bazi\u0173 varikliai \u012f nuoseklias avarijos atveju momentines kopijas reaguoja skirtingai, ta\u010diau n\u0117 vienas i\u0161 j\u0173 gamybin\u0117je aplinkoje to neatlieka skland\u017eiai.<\/p>\n<ul>\n<li><strong>PostgreSQL:<\/strong> \u201ePostgreSQL\u201c labai priklauso nuo <code>pg_wal<\/code> katalogo. Jei momentin\u0117 kopija u\u017efiksuoja duomen\u0173 katalog\u0105 (<code>$PGDATA<\/code>) ir WAL nesinchronizuotai, \u201ePostgreSQL\u201c nepavyks paleisti, i\u0161metant klaid\u0105 <code>PANIC: could not locate a valid checkpoint record<\/code>.<\/li>\n<li><strong>MySQL\/InnoDB:<\/strong> \u201eInnoDB\u201c naudoja \u201edoublewrite\u201c bufer\u012f, kad i\u0161vengt\u0173 \u201eply\u0161usi\u0173 puslapi\u0173\u201c, o tai suteikia tam tikr\u0105 apsaug\u0105 nuo nuosekli\u0173 avarijos atveju b\u016bsen\u0173. Ta\u010diau, jei <code>ibdata1<\/code> failas ir <code>ib_logfile<\/code> u\u017efiksuojami nesinchronizuotai, \u201eInnoDB\u201c variklis atk\u016brimo metu sugrius.<\/li>\n<li><strong>Microsoft SQL Server:<\/strong> \u201eSQL Server\u201c yra itin jautrus I\/O u\u017e\u0161aldymui. Be tinkamos VSS (Volume Shadow Copy Service) integracijos, \u201eSQL Server\u201c atk\u016brimas i\u0161 standartin\u0117s VM momentin\u0117s kopijos da\u017enai baigiasi \u201e\u012ftartinomis\u201c (suspect) duomen\u0173 baz\u0117mis ir nutr\u016bkusiomis \u017eurnal\u0173 grandin\u0117mis, taip sunaikinant j\u016bs\u0173 galimybes atkurti duomenis konkre\u010diu laiku (PITR).<\/li>\n<\/ul>\n<h2>Geriausia praktika saugiam virtualizuot\u0173 duomen\u0173 bazi\u0173 atsargini\u0173 kopij\u0173 k\u016brimui<\/h2>\n<p>Nor\u0117dami apsaugoti transakcines duomen\u0173 bazes, turite pereiti nuo nuosekli\u0173 avarijos atveju atsargini\u0173 kopij\u0173 prie <strong>nuosekli\u0173 programos lygiu<\/strong> atsargini\u0173 kopij\u0173. Tai reikalauja, kad atsargini\u0173 kopij\u0173 k\u016brimo mechanizmas susisiekt\u0173 su duomen\u0173 baz\u0117s varikliu, priversdamas j\u012f i\u0161valyti atmint\u012f \u012f disk\u0105 ir laikinai pristabdyti I\/O operacijas, kol daroma momentin\u0117 kopija.<\/p>\n<h3>1. Pasinaudokite programos lygio u\u017e\u0161aldymu (VSS ir fsfreeze)<\/h3>\n<p><strong>\u201eWindows\u201c (SQL Server):<\/strong><br \/>\nVisada u\u017etikrinkite, kad j\u016bs\u0173 atsargini\u0173 kopij\u0173 k\u016brimo sprendimas naudoja \u201eMicrosoft Volume Shadow Copy Service\u201c (VSS). Kai inicijuojama VSS palaikanti atsargin\u0117 kopija, \u201eSQL Server VSS Writer\u201c u\u017e\u0161aldo duomen\u0173 baz\u0117s I\/O, i\u0161valo laukian\u010dias transakcijas \u012f disk\u0105 ir u\u017etikrina, kad momentin\u0117 kopija b\u016bt\u0173 visi\u0161kai nuosekli programos lygiu.<\/p>\n<p><strong>\u201eLinux\u201c (PostgreSQL \/ MySQL):<\/strong><br \/>\n\u201eLinux\u201c neturi vietinio VSS atitikmens. Nor\u0117dami pasiekti programos lygio nuoseklum\u0105, turite naudoti \u201epre-freeze\u201c ir \u201epost-thaw\u201c scenarijus kartu su hipervizoriaus sve\u010dio \u012frankiais (pvz., \u201eVMware Tools\u201c).<\/p>\n<p>\u0160tai \u201eVMware\u201c <code>pre-freeze-script<\/code> pavyzdys \u201ePostgreSQL 15+\u201c versijai, kuris saugiai paruo\u0161ia duomen\u0173 baz\u0119 momentinei kopijai:<\/p>\n<pre><code class=\"language-bash\">#!\/bin\/bash\n# \/usr\/sbin\/pre-freeze-script\n# \u012esitikinkite, kad \u0161is scenarijus yra vykdomasis (chmod +x)\n\n# 1. Nurodykite \u201ePostgreSQL\u201c pasiruo\u0161ti atsarginei kopijai\nsu - postgres -c \"psql -c \"SELECT pg_backup_start('vm_snapshot', true);\"\"\n\n# 2. I\u0161valykite fail\u0173 sistemos buferius \u012f disk\u0105\nsync\n\n# 3. U\u017e\u0161aldykite fail\u0173 sistem\u0105 (darant prielaid\u0105, kad duomenys yra \/var\/lib\/pgsql)\nfsfreeze -f \/var\/lib\/pgsql\n<\/code><\/pre>\n<p>Ir atitinkamas <code>post-thaw-script<\/code> operacijoms atnaujinti:<\/p>\n<pre><code class=\"language-bash\">#!\/bin\/bash\n# \/usr\/sbin\/post-thaw-script\n\n# 1. At\u0161aldykite fail\u0173 sistem\u0105\nfsfreeze -u \/var\/lib\/pgsql\n\n# 2. Nurodykite \u201ePostgreSQL\u201c, kad atsargin\u0117 kopija baigta\nsu - postgres -c \"psql -c \"SELECT pg_backup_stop();\"\"\n<\/code><\/pre>\n<h3>2. Naudokite vietines duomen\u0173 bazi\u0173 atsargini\u0173 kopij\u0173 priemones<\/h3>\n<p>Nors programos lygiu nuoseklios momentin\u0117s kopijos yra geriau nei standartin\u0117s, jos vis tiek kelia VM sustingimo rizik\u0105. Saugiausias b\u016bdas duomen\u0173 bazi\u0173 atsargin\u0117ms kopijoms \u2013 naudoti vietines, srautines atsargini\u0173 kopij\u0173 priemones, kurios veikia nepriklausomai nuo hipervizoriaus.<\/p>\n<p><strong>PostgreSQL (pg_basebackup):<\/strong><\/p>\n<pre><code class=\"language-bash\">pg_basebackup -h localhost -U replication_user -D \/mnt\/backups\/pg_backup -Ft -z -P\n<\/code><\/pre>\n<p><strong>MySQL\/MariaDB (Percona XtraBackup \/ Mariabackup):<\/strong><br \/>\n\u0160ie \u012frankiai daro \u201ekar\u0161tas\u201c, neblokuojan\u010dias atsargines kopijas, kopijuodami duomen\u0173 failus ir kartu sekdami pakeitimus \u201eredo\u201c \u017eurnale.<\/p>\n<pre><code class=\"language-bash\">mariabackup --backup --target-dir=\/mnt\/backups\/mysql_backup --user=root --password=SecurePass\n<\/code><\/pre>\n<p><strong>SQL Server (T-SQL):<\/strong><\/p>\n<pre><code class=\"language-sql\">BACKUP DATABASE [ProductionDB] \nTO DISK = N'Z:BackupsProductionDB.bak' \nWITH NOFORMAT, NOINIT, NAME = N'ProductionDB-Full Backup', \nSKIP, NOREWIND, NOUNLOAD, COMPRESSION, STATS = 10;\nGO\n<\/code><\/pre>\n<h3>3. \u012ediekite atk\u016brim\u0105 konkre\u010diu laiku (PITR) per \u017eurnal\u0173 archyvavim\u0105<\/h3>\n<p>Kasdien\u0117 momentin\u0117 kopija ar pilna atsargin\u0117 kopija apsaugo jus tik iki tos minut\u0117s, kai ji buvo padaryta. Jei j\u016bs\u0173 duomen\u0173 baz\u0117 sugenda 16:00 val., o paskutin\u0117 momentin\u0117 kopija buvo 02:00 val., prarandate 14 valand\u0173 transakcini\u0173 duomen\u0173.<\/p>\n<p>Nor\u0117dami pasiekti tikr\u0105 \u012fmon\u0117s lygio atsparum\u0105, turite derinti pilnas, programos lygiu nuoseklias atsargines kopijas su nuolatiniu \u017eurnal\u0173 archyvavimu (WAL, \u201eRedo\u201c \u017eurnal\u0173 ar transakcij\u0173 \u017eurnal\u0173 atsargini\u0173 kopij\u0173 k\u016brimas kas kelias minutes). Tai leid\u017eia duomen\u0173 bazi\u0173 administratoriams atkurti duomen\u0173 baz\u0119 iki konkre\u010dios minut\u0117s ar net konkretaus transakcijos ID prie\u0161 \u012fvykstant nelaimei.<\/p>\n<h2>\u012emon\u0117s atsargini\u0173 kopij\u0173 strategijos su \u201eCloudSave\u201c<\/h2>\n<p>Individuali\u0173 \u201epre-freeze\u201c scenarij\u0173, \u201ecron\u201c u\u017eduo\u010di\u0173 vietiniams duomen\u0173 baz\u0117s i\u0161ra\u0161ams ir \u017eurnal\u0173 siuntimo valdymas de\u0161imtyse duomen\u0173 bazi\u0173 serveri\u0173 yra operacinis ko\u0161maras \u201eDevOps\u201c komandoms. \u010cia tampa kriti\u0161kai svarbi \u012fmon\u0117s lygio platforma, tokia kaip \u201eCloudSave\u201c.<\/p>\n<p>\u201eCloudSave\u201c sujungia virtualizacij\u0105 ir duomen\u0173 bazi\u0173 architekt\u016br\u0105. U\u017euot pasikliovusi aklais hipervizoriaus momentiniais vaizdais, \u201eCloudSave\u201c naudoja programos lygio agentus, kurie nat\u016braliai integruojasi su \u201eSQL Server\u201c, \u201ePostgreSQL\u201c, \u201eMySQL\u201c ir \u201eOracle\u201c.<\/p>\n<p>Kai \u201eCloudSave\u201c inicijuoja atsargin\u0119 kopij\u0105:<br \/>\n1. Ji tiesiogiai bendrauja su duomen\u0173 baz\u0117s varikliu per vietines API (pvz., VSS \u201eWindows\u201c arba vietin\u012f WAL srautin\u012f perdavim\u0105 \u201eLinux\u201c).<br \/>\n2. Ji suderina atminties buferi\u0173 i\u0161valym\u0105 \u012f disk\u0105 nesukeldama trikdan\u010di\u0173 VM sustingim\u0173.<br \/>\n3. Ji saugiai u\u017efiksuoja duomen\u0173 failus ir automati\u0161kai valdo transakcij\u0173 \u017eurnal\u0173 sutrumpinim\u0105.<br \/>\n4. Ji nuolat kuria transakcij\u0173 \u017eurnal\u0173 atsargines kopijas, \u012fgalindama tiksl\u0173 atk\u016brim\u0105 konkre\u010diu laiku (PITR) vos keliais paspaudimais.<\/p>\n<p>Perleisdami programos lygio nuoseklumo sud\u0117tingum\u0105 \u201eCloudSave\u201c, duomen\u0173 bazi\u0173 administratoriai ir sistem\u0173 administratoriai gali garantuoti duomen\u0173 vientisum\u0105 neaukodami savo gamybini\u0173 klasteri\u0173 na\u0161umo ar pasiekiamumo.<\/p>\n<h2>I\u0161vada<\/h2>\n<p>Virtuali\u0173j\u0173 ma\u0161in\u0173 momentin\u0117s kopijos yra ne\u012ftik\u0117tinas \u012frankis infrastrukt\u016bros valdymui, ta\u010diau jos i\u0161 esm\u0117s nesuderinamos su transakcini\u0173 duomen\u0173 bazi\u0173 ACID reikalavimais. Pasikliovimas nuosekliomis avarijos atveju hipervizoriaus momentin\u0117mis kopijomis j\u016bs\u0173 organizacij\u0105 atveria \u201eply\u0161usi\u0173 puslapi\u0173\u201c, nutr\u016bkusi\u0173 replikacijos grandini\u0173 ir katastrofi\u0161ko duomen\u0173 praradimo rizikai.<\/p>\n<p>Nor\u0117dami apsaugoti savo kritinius duomenis, privalote \u012fdiegti programos lygio u\u017e\u0161aldym\u0105, naudoti vietines duomen\u0173 bazi\u0173 atsargini\u0173 kopij\u0173 metodikas ir palaikyti nuolatinius transakcij\u0173 \u017eurnal\u0173 archyvus. Priimdami specialiai tam sukurtus \u012fmon\u0117s lygio atsargini\u0173 kopij\u0173 sprendimus, galite u\u017etikrinti, kad j\u016bs\u0173 duomen\u0173 baz\u0117s i\u0161liks itin pasiekiamos, visi\u0161kai atkuriamos ir visi\u0161kai saugios.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>&gt; Discover why standard VM snapshots cause data corruption in transactional databases like PostgreSQL and SQL Server. 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