{"id":106149,"date":"2022-12-18T21:36:39","date_gmt":"2022-12-18T19:36:39","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/v-yadro-linux-6-2-vojdut-uluchsheniya-raid5-6-v-btrfs"},"modified":"2022-12-18T21:36:39","modified_gmt":"2022-12-18T19:36:39","slug":"v-yadro-linux-6-2-vojdut-uluchsheniya-raid5-6-v-btrfs","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/news\/v-yadro-linux-6-2-vojdut-uluchsheniya-raid5-6-v-btrfs","title":{"rendered":"Do jadra Linux 6.2 bud\u00fa zahrnut\u00e9 vylep\u0161enia RAID5\/6 v Btrfs","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Pre verziu Linux 6.2 s\u00fa navrhnut\u00e9 vylep\u0161enia Btrfs t\u00fdkaj\u00face sa opravy probl\u00e9mu \u201ewrite hole\u201c v implement\u00e1cii RAID 5\/6. Podstata probl\u00e9mu spo\u010d\u00edva v tom, \u017ee ak sa zr\u00fatenie vyskytne po\u010das z\u00e1pisu, p\u00f4vodne nie je mo\u017en\u00e9 ur\u010di\u0165, ktor\u00fd blok na ktorom z RAID zariaden\u00ed bol spr\u00e1vne zap\u00edsan\u00fd a v ktorom bol z\u00e1pis nedokon\u010den\u00fd. Pri pokuse o obnovenie RAID v podobnej situ\u00e1cii m\u00f4\u017ee d\u00f4js\u0165 k po\u0161kodeniu blokov, ktor\u00e9 zodpovedaj\u00fa nedokon\u010den\u00fdm blokom, preto\u017ee stav blokov RAID je nesynchronizovan\u00fd. Tento probl\u00e9m sa vyskytuje vo v\u0161etk\u00fdch maticiach RAID1\/5\/6, kde neboli prijat\u00e9 \u0161peci\u00e1lne opatrenia na boj s t\u00fdmto efektom. <\/p>\n

V implement\u00e1cii RAID, ako je RAID1 v btrfs, sa tento probl\u00e9m vyrie\u0161i pou\u017eit\u00edm kontroln\u00fdch s\u00fam na oboch k\u00f3pi\u00e1ch; pri nes\u00fahlase sa d\u00e1ta jednoducho obnovia z druhej k\u00f3pie. Tento pr\u00edstup tie\u017e funguje ak nejak\u00e9 zariadenie za\u010d\u00edna poskytova\u0165 nekorektn\u00e9 d\u00e1ta namiesto \u00fapln\u00e9ho zlyhania. <\/p>\n

Av\u0161ak v pr\u00edpade RAID5\/6 s\u00faborov\u00fd syst\u00e9m neuchov\u00e1va kontroln\u00e9 s\u00famy pre bloky paritn\u00fdch d\u00e1t: v norm\u00e1lnej situ\u00e1cii sa spr\u00e1vnos\u0165 blokov overuje t\u00fdm faktom, \u017ee s\u00fa v\u0161etky vybaven\u00e9 kontrolnou s\u00famou a blok paritn\u00fdch d\u00e1t sa d\u00e1 obnovi\u0165 z d\u00e1t. Av\u0161ak v pr\u00edpade \u010diasto\u010dn\u00e9ho z\u00e1pisu tento pr\u00edstup v ur\u010dit\u00fdch situ\u00e1ci\u00e1ch nemus\u00ed fungova\u0165. V takom pr\u00edpade, pri obnove po\u013ea nie je vyl\u00fa\u010den\u00e9, \u017ee bloky, ktor\u00e9 boli s\u00fa\u010das\u0165ou nedokon\u010den\u00e9ho z\u00e1pisu, bud\u00fa obnoven\u00e9 nespr\u00e1vne. <\/p>\n

V pr\u00edpade btrfs je tento probl\u00e9m najaktu\u00e1lnej\u0161\u00ed, ak je vykon\u00e1van\u00fd z\u00e1pis men\u0161\u00ed ako stripe. V tomto pr\u00edpade mus\u00ed s\u00faborov\u00fd syst\u00e9m vykona\u0165 oper\u00e1ciu \u010d\u00edtania-modifik\u00e1cie-z\u00e1pisu (read-modify-write, RMW). Ak sa pritom stretn\u00fa bloky s nedokon\u010den\u00fdm z\u00e1pisom, oper\u00e1cia RMW m\u00f4\u017ee sp\u00f4sobi\u0165 po\u0161kodenia, ktor\u00e9 nebud\u00fa zisten\u00e9, aj napriek kontroln\u00fdm s\u00fa\u010dtom. V\u00fdvoj\u00e1ri vykonali zmeny, ktor\u00e9 umo\u017e\u0148uj\u00fa oper\u00e1cii RMW skontrolova\u0165 kontroln\u00fd s\u00fa\u010det blokov pred vykonan\u00edm tejto oper\u00e1cie a, ak je to nevyhnutn\u00e9, vykona\u0165 aj kontrolu kontroln\u00fdch s\u00fa\u010dtov po z\u00e1pise. Bohu\u017eia\u013e, v situ\u00e1cii s nedokon\u010den\u00fdm z\u00e1pisom stripe (RMW) to vedie k dodato\u010dn\u00fdm n\u00e1kladom na v\u00fdpo\u010det kontroln\u00fdch s\u00fa\u010dtov, no z\u00e1sadne zvy\u0161uje spo\u013eahlivos\u0165. Pre RAID6 tak\u00e1 logika zatia\u013e nie je pripraven\u00e1, av\u0161ak v pr\u00edpade zlyhania v RAID6 je potrebn\u00e9, aby z\u00e1pis zlyhal s\u00fa\u010dasne na dvoch zariadeniach, \u010do je menej pravdepodobn\u00e9. <\/p>\n

\u010ealej je mo\u017en\u00e9 poznamena\u0165 odpor\u00fa\u010dania od v\u00fdvoj\u00e1rov pre pou\u017eitie RAID5\/6, ktor\u00fdch podstata spo\u010d\u00edva v tom, \u017ee v Btrfs m\u00f4\u017ee profil ukladania metad\u00e1t a d\u00e1t odli\u0161ova\u0165. Pri tom je mo\u017en\u00e9 pou\u017ei\u0165 profil RAID1 (zrkadlo) alebo dokonca RAID1C3 (3 k\u00f3pie) pre metadata, a pre d\u00e1ta RAID5 alebo RAID6. T\u00fdm sa zabezpe\u010duje spo\u013eahliv\u00e1 ochrana metad\u00e1t a absencia \u201ewrite hole\u201c na jednej strane a efekt\u00edvnej\u0161ie vyu\u017eitie priestoru charakteristick\u00e9 pre RAID5\/6 na strane druhej. To umo\u017e\u0148uje vyh\u00fdba\u0165 sa po\u0161kodeniu metad\u00e1t, pri\u010dom po\u0161kodenia d\u00e1t m\u00f4\u017eu by\u0165 opraven\u00e9. <\/p>\n

Taktie\u017e je mo\u017en\u00e9 poznamena\u0165, \u017ee pre SSD v Btrfs v jadre 6.2 bude predvolene aktivovan\u00e9 asynchr\u00f3nne vykon\u00e1vanie oper\u00e1cie \u201ediscard\u201c (zna\u010denie uvo\u013enen\u00fdch blokov, ktor\u00e9 u\u017e nie je potrebn\u00e9 fyzicky uklada\u0165). V\u00fdhodou tohto re\u017eimu je vysok\u00fd v\u00fdkon v\u010faka efekt\u00edvnemu skupinovaniu oper\u00e1ci\u00ed \u201ediscard\u201c do fronty a n\u00e1sledn\u00e9mu spracovaniu fronty pozad\u00edm, v\u010faka \u010domu be\u017en\u00e9 oper\u00e1cie FS nie s\u00fa spomalen\u00e9, ako v pr\u00edpade synchronn\u00e9ho \u201ediscard\u201c pri uvo\u013e\u0148ovan\u00ed blokov, a SSD m\u00f4\u017ee robi\u0165 lep\u0161ie rozhodnutia. Na druhej strane u\u017e nebude potrebn\u00e9 pou\u017e\u00edva\u0165 n\u00e1stroje typu fstrim, preto\u017ee v\u0161etky dostupn\u00e9 bloky bud\u00fa \u010disten\u00e9 v FS bez potreby dodato\u010dn\u00e9ho skenovania a bez spomalenia oper\u00e1ci\u00ed.
\n
Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0414\u043b\u044f \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u044f\u0434\u0440\u043e Linux 6.2 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u044b \u0443\u043b\u0443\u0447\u0448\u0435\u043d\u0438\u044f Btrfs, \u043a\u0430\u0441\u0430\u044e\u0449\u0438\u0435\u0441\u044f \u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b «write hole» \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 RAID 5\/6. \u0421\u0443\u0442\u044c \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0441\u0432\u043e\u0434\u0438\u0442\u0441\u044f \u043a \u0442\u043e\u043c\u0443, \u0447\u0442\u043e \u0435\u0441\u043b\u0438 \u043a\u0440\u0430\u0445 \u0441\u043b\u0443\u0447\u0438\u043b\u0441\u044f \u0432\u043e \u0432\u0440\u0435\u043c\u044f \u0437\u0430\u043f\u0438\u0441\u0438, \u0438\u0437\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u043e \u043d\u0435\u0432\u043e\u0437\u043c\u043e\u0436\u043d\u043e \u043f\u043e\u043d\u044f\u0442\u044c \u043a\u0430\u043a\u043e\u0439 \u0431\u043b\u043e\u043a \u043d\u0430 \u043a\u0430\u043a\u043e\u043c \u0438\u0437 \u0443\u0441\u0442\u0440\u043e\u0439\u0441\u0442\u0432 RAID \u0437\u0430\u043f\u0438\u0441\u0430\u043b\u0441\u044f \u043a\u043e\u0440\u0440\u0435\u043a\u0442\u043d\u043e, \u0430 \u0432 \u043a\u0430\u043a\u043e\u043c \u0437\u0430\u043f\u0438\u0441\u044c \u043d\u0435 \u0431\u044b\u043b\u0430 \u0437\u0430\u0432\u0435\u0440\u0448\u0435\u043d\u0430. \u0412 \u0441\u043b\u0443\u0447\u0430\u0435 \u043f\u043e\u043f\u044b\u0442\u043a\u0438 \u0432\u043e\u0441\u0441\u0442\u0430\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f RAID \u0432 \u043f\u043e\u0434\u043e\u0431\u043d\u043e\u0439 […]<\/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":[702],"tags":[],"class_list":["post-106149","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Do jadra Linux 6.2 pr\u00eddu vylep\u0161enia RAID5\/6 v Btrfs | ProHoster","description":"Pre jadro Linux 6.2 s\u00fa navrhnut\u00e9 vylep\u0161enia Btrfs, t\u00fdkaj\u00face sa opravy probl\u00e9mu \"write hole\" v implement\u00e1cii RAID 5\/6.","canonical_url":"https:\/\/prohoster.info\/sk\/blog\/news\/v-yadro-linux-6-2-vojdut-uluchsheniya-raid5-6-v-btrfs","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"sk_SK","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0412 \u044f\u0434\u0440\u043e Linux 6.2 \u0432\u043e\u0439\u0434\u0443\u0442 \u0443\u043b\u0443\u0447\u0448\u0435\u043d\u0438\u044f RAID5\/6 \u0432 Btrfs | ProHoster","og:description":"\u0414\u043b\u044f \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u044f\u0434\u0440\u043e Linux 6.2 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u044b \u0443\u043b\u0443\u0447\u0448\u0435\u043d\u0438\u044f Btrfs, \u043a\u0430\u0441\u0430\u044e\u0449\u0438\u0435\u0441\u044f \u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b "write hole" \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 RAID 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