RAID algorithms tau qhia rau pej xeem rov qab rau xyoo 1987. Txog rau hnub no, lawv tseem yog cov thev naus laus zis nrov tshaj plaws rau kev tiv thaiv thiab nrawm nkag mus rau cov ntaub ntawv hauv kev khaws cov ntaub ntawv. Tab sis lub hnub nyoog ntawm IT thev naus laus zis, uas tau hla 30-xyoo lub cim, tsis yog kev loj hlob, tab sis twb laus lawm. Yog vim li cas yog kev vam meej, uas inexorably nqa lub cib fim tshiab. Nyob rau lub sijhawm thaum tsis muaj lwm yam tsav uas tsis yog HDDs, RAID algorithms ua rau nws muaj peev xwm ua kom muaj txiaj ntsig zoo tshaj plaws ntawm cov peev txheej khaws cia. Txawm li cas los xij, nrog rau qhov tshwm sim ntawm SSDs, qhov xwm txheej tau hloov pauv radically. Tam sim no RAID thaum ua hauj lwm nrog solid-state drives twb yog "noose" ntawm lawv cov kev ua tau zoo. Yog li ntawd, txhawm rau qhib tag nrho lub peev xwm ntawm SSD ceev cov yam ntxwv, kev sib txawv kiag li rau kev ua haujlwm nrog lawv tsuas yog tsim nyog.
Ntxiv rau qhov pom tseeb qhov sib txawv ntawm HDD thiab SSD hauv cov hauv paus ntsiab lus ntawm kev khiav hauj lwm, cov hom xov xwm no muaj ib qho tseem ceeb tshaj plaws: txhua lub hard drive tuaj yeem sau cov ntaub ntawv nrog cov ntawv loj ntawm ib qho thaiv (tam sim no feem ntau yog 4KB). Rau SSDs, cov txheej txheem rov sau dua yog txheej txheem nyuaj dua:
- Cov ntaub ntawv hloov pauv yog theej rau qhov chaw tshiab. Hauv qhov no, qhov granularity yog tib qhov thaiv, tab sis muaj ntau nplooj ntawv thiab muaj qhov loj ntawm 256KB - 4MB. Cov. thaum hloov tib 4KB, nws yog ib qho tsim nyog yuav tau luam, ntawm lwm yam, tag nrho cov nplooj ntawv uas nyob ib sab uas tsim ib qho thaiv.
- Kos "qub" blocks li tsis siv, yog li ntawd lawv tuaj yeem raug tshem tawm los ntawm Cov Neeg Sau Cov Khib Nyiab.
Sequential sau/overwrite rau SSD
Nyob rau hauv cov ntaub ntawv ntawm sequential sau / rewriting, qhov no feature ntawm SSD tsis ua lub luag hauj lwm loj nyob rau hauv cov nqe lus ntawm nws kev ua tau zoo, vim hais tias cov blocks nyob ze, thiab cov khoom khib nyiab ua nws txoj haujlwm zoo heev hauv keeb kwm yav dhau. Tab sis hauv lub neej tiag tiag, thiab ntau dua li hauv ntu Kev Lag Luam, kev nkag mus rau cov ntaub ntawv feem ntau yog siv rau SSDs. Thiab cov ntaub ntawv no yog sau rau qhov chaw nyob ntawm lub drives.
Cov ntaub ntawv ntau yog sau rau SSD, qhov nyuaj dua nws yog rau cov khoom siv khib nyiab ua haujlwm, txij li kev tawg paj ntau ntxiv. Raws li qhov tshwm sim, lub sijhawm los txog thaum cov txheej txheem ntawm kev ntxuav lub tsav tsis yog "tom qab": kev ua haujlwm ntawm SSD poob qis, vim tias ib feem tseem ceeb ntawm nws yog coj los ntawm khib nyiab Collector.
Cov ntaub ntawv tiag tiag qhov chaw ntawm SSD thaum siv txhua hnub
Txhawm rau piav qhia txog cov txiaj ntsig ntawm kev ua haujlwm ntawm cov khoom khib nyiab, nyob ntawm hom kev kaw lus ntawm lub tsav, koj tuaj yeem ua qhov kev sim yooj yim tshaj plaws: kev sib txuas lus thiab sau ntawv tsis sib xws hauv 4KB blocks ntawm 100GB tsav. (Source - tuam txhab )
Sequential Write Performance
Random sau kev ua tau zoo
Raws li tuaj yeem pom los ntawm kev ntsuas, qhov kev ua haujlwm poob tuaj yeem ncav cuag ntau tshaj ob zaug. Thiab qhov no tsuas yog ib qho tsav xwb. Thaum siv SSD ua ib feem ntawm pawg RAID, tus lej ntawm kev sau ntawv rov ua haujlwm tau nce ntau vim ua haujlwm nrog kev sib luag.
Feem ntau, vim cov yam ntxwv ntawm SSD kev ua haujlwm, muaj qhov tsis zoo li no rau lawv raws li kev sau ua kom nrov. Qhov no yog qhov piv ntawm tus nqi ntawm cov ntaub ntawv sau rau tus tsav mus rau tus nqi ntawm cov ntaub ntawv tus tswv tsev tau xa. Thiab rau qhov nrov tshaj plaws RAID5 qhov coefficient yog ~ 3.5.
Raws li qhov tshwm sim, cov tshuab nrog classic RAID yeej siv SSDs tsuas yog ~ 10% ntawm lawv qhov kev ceev tiag tiag thiab qhov ntsuas tsis zoo hauv kev ua haujlwm thaum tus naj npawb ntawm cov tsav tsheb nce mus rau ntau tshaj li kaum.
Peb kuj tseem nco ntsoov tias kev sau ntawv ntau dhau tsis tsuas yog txo qhov kev ua tau zoo ntawm SSD, tab sis kuj txo nws qhov deb ntawm cov peev txheej tsis kawg, yog li ua rau lub neej ua haujlwm luv ntawm lub tsav.
, uas yog lub hauv paus ntawm tag nrho cov khoom AccelStor, yog tsim los ua ib qho kev xaiv rau classic RAID algorithms thaum ua haujlwm nrog SSDs. Kev tsim kho tshiab ntawm thev naus laus zis tau sau tseg ob qho tib si los ntawm ntau yam patents thiab khoom plig (xws li ntawm Flash Memory Summit 2016), thiab los ntawm cov txiaj ntsig ntawm kev sim ywj pheej (piv txwv li, SPC1).
Ntsiab lus muaj kev hloov pauv tag nrho cov ntawv thov tuaj, feem ntau ntawm hom random, rau hauv ib txheej ntawm cov blocks uas zoo ib yam li qhov ua tau raws li qhov ua tau raws li kev sau hom los ntawm qhov pom ntawm tus tsav. Raws li qhov tshwm sim, kev kaw cia rau SSD tshwm sim nyob rau hauv hom kev nyiam tshaj plaws rau lawv, thiab qhov ua tau zoo tshaj qhov system nrog RAID classic.
Txhua SSDs hauv AccelStor systems tau muab faib ua ob pawg FlexiRemap® symmetrical. Cov pab pawg loj nyob ntawm tus qauv thiab thaj tsam ntawm 5-11 tsav. Rau kev ua txhaum cai nyob rau hauv pab pawg, parity yog siv zoo ib yam li RAID5. Ob pawg yog siv ua ke los tsim ib qho chaw khaws cia. Yog li ntawd, qhov ua rau ua txhaum cai yuav zoo ib yam li RAID50 array uas muaj ob pawg: lub kaw lus tuaj yeem tiv taus qhov tsis ua haujlwm txog li ob SSDs, tab sis tsis pub ntau tshaj ib qho ntawm txhua pawg FlexiRemap®.
Tag nrho cov ntawv thov nkag tau muab faib ua 4KB blocks, uas tau sau rau hauv hom robin rau ob pawg FlexiRemap®. Nyob rau tib lub sijhawm, lub kaw lus tsis tu ncua ua raws li qhov kev thov rau cov blocks kaw, sim sau cov blocks zoo sib xws kom ze rau ib leeg li sai tau thaum lawv hloov. Nws hloov tawm mus ua ib tug virtual analogue ntawm kev sib koom, yog hais tias qhia nyob rau hauv cov nqe lus ntawm cia systems. Hauv qhov no, kev ua haujlwm ntawm cov khoom siv khib nyiab tau yooj yim heev: tom qab tag nrho, cov blocks tsis siv yuav ib txwm nyob ze.
Nws yog tsim nyog sau cia tias Tsis zoo li cov neeg sib tw cov khoom lag luam, lawv tsis siv cov kev ua haujlwm ntawm caching cov lus thov tuaj rau hauv tus maub los lub RAM. Tag nrho cov ntaub ntawv nkag tau raug sau tam sim ntawd rau SSD. Tus tswv tsev tau txais kev pom zoo ntawm kev ua tiav cov ntaub ntawv tsuas yog tom qab cov ntaub ntawv raug muab tso rau ntawm lub drives. RAM tsuas yog khaws cov ntawv thaiv qhov chaw ntawm SSD kom nrawm nkag mus thiab txiav txim siab qhov twg los sau cov ntaub ntawv txuas ntxiv. Tau kawg, rau kev ntseeg siab, cov ntawv luam ntawm cov rooj no nyob rau hauv xov xwm lawv tus kheej. Raws li qhov tshwm sim, AccelStor systems tsis tas yuav muaj kev tiv thaiv cache hauv daim ntawv ntawm lub roj teeb / capacitor (txawm li cas los xij, muaj peev xwm sib txuas lus nrog UPS yog muaj rau "mos" kaw thaum muaj teeb meem hluav taws xob).
Ua tsaug rau txoj hauv kev no rau kev teeb tsa cov ntaub ntawv, cov khoom khib nyiab tuaj yeem ua haujlwm hauv keeb kwm yav dhau yam tsis muaj kev cuam tshuam rau kev ceev ntawm cov tsav, uas thaum kawg tso cai rau 90% ntawm SSD kev ua tau zoo los siv hauv lub kaw lus. Qhov no yog qhov tseeb yog vim li cas rau qhov siab IOPS tus nqi hauv AccelStor systems piv rau Txhua Flash, uas yog raws li RAID algorithms.
Lwm qhov tseem ceeb ntawm FlexiRemap® thev naus laus zis yog qhov tseem ceeb ntawm kev txo qis hauv cov ntawv sau tsis tu ncua rau SSDs. Yog li, qhov tseem ceeb tshaj plaws ntawm kev sau ntawv rau AccelStor systems tsuas yog 1.3, uas, txhais ua hom lus, txhais tau hais tias kev nce hauv kev pab cuam lub neej ntawm drives piv rau RAID5 ntau dua 2.5 npaug!
Ua tsaug rau qhov kev saib xyuas tas li ntawm cov ntaub ntawv tso cai txoj cai ntawm SSDs, txhua qhov tsav tau sib npaug. Txoj hauv kev no tso cai rau koj los kwv yees lawv lub neej kev pab cuam thiab xa cov teeb liab mus rau tus thawj tswj hwm ua ntej txog kev qaug zog ntawm cov ntaub ntawv kaw.
Nws yog qhov tseeb tias SSDs tuaj yeem ua tsis tiav. Nyob rau hauv cov ntaub ntawv no, lub system yuav tam sim ntawd pib rebuilding rau ib qho ntawm cov kub spare disks. Qhov no ua rau pawg FlexiRemap® nyob rau hauv lub xeev degraded los ua nyeem nkaus xwb, thiab tag nrho cov ntawv thov raug xa mus rau pawg thib ob. Cov txheej txheem kev tiv thaiv no yog muab los ua kom lub zog rov tsim kho thiab txo qhov kev pheej hmoo ntawm kev tsis ua haujlwm ntawm lwm tus tsav hauv tib pab pawg. Nws tsis pub leejtwg paub tias thaum lub sijhawm rov tsim kho dua, txhua qhov kev tsav tsheb hauv ib pab pawg tau nce siab vim muaj kev cuam tshuam los ntawm kev nyeem, sau ntawv, thiab rov ua haujlwm ntawm qhov chaw kub. Qhov no ua rau muaj qhov ua tau ntawm lwm qhov tsis ua haujlwm disk. Thiab qhov kev sau ntawv ntau dua, qhov kev rov tsim dua yuav siv sijhawm ntev dua.
Thaum cov txheej txheem kho tiav thiab FlexiRemap® pab pawg rov qab mus rau qhov qub, yuav muaj qhov tsis txaus ntseeg me ntsis hauv kev sau cov peev txheej ntawm ob pawg. Yog li ntawd, txhawm rau txhim kho nws, kev sau ntawv tom ntej yuav poob rau ntawm pawg rov qab los (ntawm chav kawm, nyob rau hauv ib txoj kev uas qhov kev ua tau zoo kawg nkaus tsis raug kev txom nyem ntau).
Nws tsis muaj peev xwm ua kom muaj kev ua tau zoo ntawm Txhua Lub Tshuab Flash raws li RAID algorithms saum toj no qee qhov txiaj ntsig (~ 280K IOPS @ 4K random sau) txawm tias siv cov tshuab caching nyuaj. FlexiRemap® thev naus laus zis, ua tsaug rau txoj hauv kev sib txawv kiag li los txhim kho qhov chaw cia, tsis tsuas yog yooj yim kov yeej qhov teeb meem no, tab sis kuj ua rau lub neej ua haujlwm ntawm SSDs ntau zaus. Yog li cov systems muaj qhov zoo tshaj plaws ntawm Tag Nrho Flash arrays ntawm ntau qhov chaw (IOPS / $, GB / $, TCO, ROI), ua rau lawv cov neeg sib tw zoo tshaj plaws rau txoj haujlwm tseem ceeb hauv cov neeg siv khoom cov ntaub ntawv los daws cov dej num hnyav.
Tau qhov twg los: www.hab.com
