{"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\/ro\/blog\/news\/v-yadro-linux-6-2-vojdut-uluchsheniya-raid5-6-v-btrfs","title":{"rendered":"\u00cembun\u0103t\u0103\u021biri RAID5\/6 vor fi incluse \u00een kernelul Linux 6.2","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Pentru activarea kernelului Linux 6.2, au fost propuse \u00eembun\u0103t\u0103\u021biri pentru Btrfs, referitoare la remedierea problemei \u201ewrite hole\u201d \u00een implementarea RAID 5\/6. Esen\u021ba problemei const\u0103 \u00een faptul c\u0103, \u00een cazul unei defec\u021biuni \u00een timpul scrierii, ini\u021bial nu se poate determina care bloc de pe care dintre dispozitivele RAID a fost scris corect, \u0219i \u00een care scrierea nu a fost finalizat\u0103. Atunci c\u00e2nd se \u00eencearc\u0103 recuperarea RAID \u00een aceast\u0103 situa\u021bie, pot ap\u0103rea distrugeri ale blocurilor corespunz\u0103toare blocurilor neterminate, deoarece starea blocurilor RAID devine nesincronizat\u0103. Aceast\u0103 problem\u0103 apare \u00een orice aranjamente RAID1\/5\/6, unde nu se adopt\u0103 m\u0103suri speciale pentru a combate un astfel de efect. <\/p>\n

\u00cen implementarea RAID, precum RAID 1 \u00een btrfs, aceast\u0103 problem\u0103 este rezolvat\u0103 prin utilizarea sumelor de control \u00een ambele copii; \u00een caz de neconcordan\u021b\u0103, datele sunt pur \u0219i simplu restaurate din a doua copie. Aceast\u0103 abordare se aplic\u0103 \u0219i \u00een cazul \u00een care un dispozitiv \u00eencepe s\u0103 returneze date incorecte \u00een loc de o defec\u021biune complet\u0103. <\/p>\n

Cu toate acestea, \u00een cazul RAID 5\/6, sistemul de fi\u0219iere nu p\u0103streaz\u0103 sume de control pentru blocurile de paritate: \u00een situa\u021bii normale, corectitudinea blocurilor este verificat\u0103 prin faptul c\u0103 toate sunt echipate cu o sum\u0103 de control, iar blocul de paritate poate fi recreat din date. Totu\u0219i, \u00een cazul unei scrieri par\u021biale, aceast\u0103 abordare poate s\u0103 nu func\u021bioneze \u00een anumite situa\u021bii. \u00cen acest caz, la recuperarea aranjamentului, nu este exclus ca blocurile afectate de scrierea incomplet\u0103 s\u0103 fie restaurate incorect. <\/p>\n

\u00cen cazul btrfs, aceast\u0103 problem\u0103 este cea mai relevant\u0103 atunci c\u00e2nd scrierea efectuat\u0103 este ca m\u0103rime mai mic\u0103 dec\u00e2t stripe-ul. \u00cen acest caz, sistemul de fi\u0219iere trebuie s\u0103 efectueze opera\u021bia de citire-modificare-scriere (read-modify-write, RMW). Dac\u0103 \u00eent\u00e2lnim blocuri cu scriere incomplet\u0103, atunci opera\u021bia RMW poate provoca distrugeri care nu vor fi detectate, \u00een ciuda sumelor de control. Dezvoltatorii au adus modific\u0103ri prin care opera\u021bia RMW verific\u0103 suma de control a blocurilor \u00eenainte de a efectua aceast\u0103 opera\u021bie, iar, \u00een cazul necesit\u0103\u021bii de recuperare a datelor, efectueaz\u0103 \u0219i verificarea sumelor de control dup\u0103 scriere. Din p\u0103cate, \u00een situa\u021bia cu o scriere incomplet\u0103 a stripe-ului (RMW), acest lucru duce la costuri suplimentare pentru calculul sumelor de control, \u00eens\u0103 cre\u0219te semnificativ fiabilitatea. Pentru RAID6, aceast\u0103 logic\u0103 nu este \u00eenc\u0103 preg\u0103tit\u0103, dar, pentru o astfel de defec\u021biune \u00een RAID6, este necesar ca scrierea s\u0103 nu reu\u0219easc\u0103 pe dou\u0103 dispozitive simultan, ceea ce este mai pu\u021bin probabil. <\/p>\n

De asemenea, se pot men\u021biona recomand\u0103rile dezvoltatorilor pentru utilizarea RAID5\/6, care constau \u00een faptul c\u0103 \u00een Btrfs profilul de stocare a metadatelor \u0219i datelor poate diferi. \u00cen acest sens, se poate utiliza un profil RAID1 (oglindire) sau chiar RAID1C3 (3 copii) pentru metadate, iar pentru date RAID5 sau RAID6. Aceasta asigur\u0103 o protec\u021bie fiabil\u0103 a metadatelor \u0219i absen\u021ba \u201ewrite hole\u201d de o parte \u0219i o utilizare mai eficient\u0103 a spa\u021biului, specific\u0103 pentru RAID5\/6, de cealalt\u0103 parte. Aceasta ajut\u0103 la evitarea distrugerilor \u00een metadate, iar deterior\u0103rile datelor pot fi corectate. <\/p>\n

De asemenea, se poate men\u021biona faptul c\u0103 pentru SSD \u00een Btrfs, \u00een kernelul 6.2, va fi activat\u0103 \u00een mod implicit execu\u021bia as\u0438\u043dcron\u0103 a opera\u021biei \u201ediscard\u201d (marcarea blocurilor eliberate, care nu mai trebuie stocate fizic). Avantajul acestui mod este performan\u021ba ridicat\u0103 datorit\u0103 grup\u0103rii eficiente a opera\u021biunilor \u201ediscard\u201d \u00een coad\u0103 \u0219i ulterior procesarea acestei cozi de c\u0103tre un procesor de fundal, astfel \u00eenc\u00e2t opera\u021biunile normale ale sistemului de fi\u0219iere s\u0103 nu fie \u00eencetinite, a\u0219a cum se \u00eent\u00e2mpl\u0103 \u00een cazul \u201ediscard\u201d sincrone pe m\u0103sur\u0103 ce blocurile sunt eliberate, iar SSD-ul poate lua decizii mai favorabile. Pe de alt\u0103 parte, nu va mai fi necesar\u0103 utilizarea utilit\u0103\u021bilor de tip fstrim, deoarece toate blocurile disponibile vor fi \u0219terse \u00een sistemul de fi\u0219iere f\u0103r\u0103 a necesita o scanare suplimentar\u0103 \u0219i f\u0103r\u0103 a \u00eencetini opera\u021biunile.
\n
Sursa: opennet.ro<\/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\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\udd47\u00cembun\u0103t\u0103\u021biri RAID5\/6 \u00een Btrfs vor fi incluse \u00een nucleul Linux 6.2 | ProHoster","description":"Pentru activarea nucleului Linux 6.2, au fost propuse \u00eembun\u0103t\u0103\u021biri Btrfs, care vizeaz\u0103 remedierea problemei \"write hole\" \u00een implementarea RAID 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\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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