Ma algorithms a RAID adayambitsidwa kwa anthu kumbuyo mu 1987. Mpaka lero, iwo akadali ukadaulo wofunidwa kwambiri poteteza ndikufulumizitsa mwayi wopezeka ndi data posungira zidziwitso. Koma zaka zaukadaulo wa IT, zomwe zadutsa zaka 30, sikukula, koma ukalamba kale. Chifukwa ndi kupita patsogolo, komwe kumabweretsa mwayi watsopano. Panthawi yomwe kunalibe ma drive ena kuposa ma HDD, ma algorithms a RAID adapangitsa kuti azitha kugwiritsa ntchito moyenera zinthu zosungira zomwe zilipo. Komabe, pakubwera kwa SSD, zinthu zasintha kwambiri. Tsopano RAID ikamagwira ntchito ndi ma drive olimba ali kale "noose" pakuchita kwawo. Chifukwa chake, kuti mutsegule kuthekera konse kwa mawonekedwe a liwiro la ma SSD, njira yosiyana kwambiri yogwirira nawo ntchito imangofunika.
Kuphatikiza pa kusiyana kodziwikiratu pakati pa HDD ndi SSD pamagwiritsidwe ntchito, mitundu ya media iyi ili ndi chikhalidwe china chofunikira: hard drive iliyonse imatha kulemba deta iliyonse ndi granularity ya chipika chimodzi (tsopano ndi 4KB nthawi zambiri). Kwa SSD, njira yolembera ndizovuta kwambiri:
- Zomwe zasinthidwa zimakopedwa kumalo atsopano. Panthawi imodzimodziyo, granularity ndi chipika chomwecho, koma chokhala ndi masamba angapo ndi kukula kwa 256KB - 4MB. Iwo. posintha 4KB yomweyo, ndikofunikira kukopera, mwa zina, masamba onse oyandikana nawo omwe amapanga chipika chimodzi.
- Mipiringidzo "yakale" imalembedwa ngati yosagwiritsidwa ntchito, kotero kuti ikhoza kulembedwa ndi Wosonkhanitsa Zinyalala.
Sequential Lembani / Lembani ku SSD
Pankhani yolemba motsatizana / kulembanso, mbali iyi ya magwiridwe antchito a SSD sakhala ndi gawo lalikulu pakuchita kwake, chifukwa. midadada ili mbali ndi mbali, ndipo wotolera zinyalala amachita ntchito yake bwino kumbuyo. Koma m'moyo weniweni, komanso makamaka mu gawo la Enterprise la SSD, kugwiritsa ntchito mwachisawawa kumagwiritsidwa ntchito nthawi zambiri. Ndipo izi zimalembedwera kumalo osagwirizana pa ma drive.
Zambiri zimalembedwa ku SSD, zimakhala zovuta kwambiri kuti wotolera zinyalala agwire ntchito, popeza kugawanika kumakula kwambiri. Zotsatira zake, nthawi imabwera pamene njira yoyeretsera galimotoyo imasiya kukhala "background": ntchito ya SSD imatsika kwambiri, chifukwa. gawo lodziwika bwino limatengedwa ndi Wosonkhanitsa Zinyalala.
Malo enieni a data pa SSD pakugwiritsa ntchito tsiku ndi tsiku
Kuti muwonetse zotsatira za ntchito ya "wotolera zinyalala" kutengera momwe amalembera pagalimoto, mutha kuyesa mayeso osavuta: motsatizana komanso mwachisawawa amalemba mu midadada ya 4KB kupita pagalimoto ya 100GB. (Source - kampani )
Kulemba motsatizana
Kulemba mwachisawawa
Monga tikuwonera pamayesero, kutsika kwa magwiridwe antchito kumatha kufika nthawi zopitilira ziwiri. Ndipo ndi galimoto imodzi yokha. Pankhani yogwiritsa ntchito SSD monga gawo la gulu la RAID, kuchuluka kwa ntchito zolemberanso kumawonjezeka kwambiri chifukwa chogwira ntchito mogwirizana.
Nthawi zambiri, chifukwa cha mawonekedwe a SSD awa, kwa iwo pali chizindikiro monga cholembera chokulitsa. Ichi ndi chiŵerengero cha kuchuluka kwa deta yolembedwa pagalimoto ku kuchuluka kwa deta yotumizidwa ndi wolandirayo. Ndipo kwa RAID5 yotchuka kwambiri, chiŵerengero ichi ndi ~ 3.5.
Zotsatira zake, makina omwe ali ndi RAID yachikale amagwiritsa ntchito ma SSD ~ 10% yokha ya liwiro lawo lenileni ndikuchita bwino kwambiri pamene chiwerengero cha ma drive chikuwonjezeka kufika pa khumi ndi awiri.
Komanso dziwani kuti kulemba mochulukira sikungochepetsa magwiridwe antchito a SSD, komanso kumachepetsanso ntchito zake zopanda malire, potero kumachepetsa moyo wagalimoto.
, yomwe ndi maziko azinthu zonse za AccelStor, idapangidwa ngati m'malo mwa ma algorithms apamwamba a RAID mukamagwira ntchito ndi ma SSD. Ukadaulo waukadaulo umadziwika ndi ma patent osiyanasiyana ndi mphotho (kuphatikiza pa Flash Memory Summit 2016) komanso zotsatira za mayeso odziyimira pawokha (mwachitsanzo, SPC1).
Essence imakhala ndi kutembenuza zopempha zolembera zonse zomwe zikubwera, ndipo makamaka zamtundu wachisawawa, kukhala midadada yomwe ili yofanana momwe mungathere ndi njira yolembera yotsatizana kuchokera kumalo oyendetsa galimoto. Zotsatira zake, kulembera ma SSD kumachitika momasuka kwambiri kwa iwo, ndipo ntchito yomaliza imaposa dongosolo lililonse lomwe lili ndi RAID yapamwamba.
Ma SSD onse mu machitidwe a AccelStor amagawidwa m'magulu awiri ofananira FlexiRemap®. Kukula kwa gulu kumatengera chitsanzo ndipo ndi ma drive 5-11. Pakulekerera zolakwika mkati mwa gulu, parity imagwiritsidwa ntchito mofanana ndi RAID5. Magulu onsewa amagwiritsidwa ntchito palimodzi kuti apange malo osungiramo malo amodzi. Chifukwa chake, kulolerana kolakwika kudzakhala kofanana ndi gulu la RAID50 lomwe lili ndi magulu awiri: dongosololi limatha kupirira kulephera kwa ma SSD awiri, koma osaposa gulu limodzi la FlexiRemap®.
Zofunsira zonse zomwe zikubwera zimagawidwa kukhala midadada ya 4KB, yomwe imalembedwa mozungulira mozungulira magulu onse a FlexiRemap®. Panthawi imodzimodziyo, dongosololi limasunga nthawi zonse zolemba za kufunikira kwa midadada yojambulidwa, kuyesera kulemba midadada yofanana pafupi ndi mzake momwe zingathere pamene akusintha. Likukhalira pafupifupi analogue wa kung'ambika, ngati anasonyeza mwa mawu osungira kachitidwe. Pankhaniyi, ntchito ya "wotolera zinyalala" imathandizidwa kwambiri: pambuyo pake, midadada yosagwiritsidwa ntchito idzakhala pafupi nthawi zonse.
Ndikoyenera kuzindikira zimenezo mosiyana ndi omwe akupikisana nawo, sagwiritsa ntchito ntchito yosunga zopempha zomwe zikubwera mu RAM ya wowongolera. Zolemba zonse zomwe zikubwera zimalembedwa nthawi yomweyo ku SSD. Wolandirayo amalandira chitsimikiziro cha kulemba bwino kokha pambuyo poyika deta pama drive. Matebulo ogawira block okha pa SSD ndi omwe amasungidwa mu RAM kuti mufulumizitse kupeza ndikuzindikira komwe mungalembe chipika chotsatira. Inde, chifukwa chodalirika, makope a matebulowa amapezeka pawailesi pawokha. Zotsatira zake, machitidwe a AccelStor safuna chitetezo cha cache cha batri / capacitor (komabe, n'zotheka kulankhulana ndi UPS - chifukwa chotseka "chofewa" pakakhala mavuto a mphamvu).
Chifukwa cha njira iyi yokonzekera kujambula, wotolera zinyalala amatha kugwira ntchito kumbuyo popanda kukhudza kwambiri liwiro la ma drive, omwe pamapeto pake amalola kuti 90% ya magwiridwe antchito a SSD agwiritsidwe ntchito mkati mwadongosolo. Izi ndizochita bwino kwambiri za IOPS m'makina a AccelStor motsutsana ndi kumbuyo kwa All Flash, zomwe zimatengera ma aligorivimu a RAID.
Chinthu chinanso chofunikira paukadaulo wa FlexiRemap® ndikuchepetsa kwambiri zolemba za SSD zosafunikira. Chifukwa chake kukulitsa zolemba zamakina a AccelStor ndi 1.3 yokha, yomwe, itamasuliridwa m'zilankhulo wamba, imatanthauza kuwonjezeka kwa moyo wautumiki wamagalimoto poyerekeza ndi RAID5 nthawi zopitilira 2.5!
Chifukwa cha kuyang'aniridwa kosalekeza ndi dongosolo la ndondomeko yoyika deta pa SSD, ma drive onse amatha mofanana. Njirayi imalola kulosera za moyo wawo wautumiki ndikuwonetsa kwa woyang'anira pasadakhale za kutopa kwa gwero lojambulira.
Zikuwonekeratu kuti ma SSD amatha kulephera. Pankhaniyi, dongosololi nthawi yomweyo liyamba kumangidwanso ku imodzi mwama disks otentha. Pachifukwa ichi, gulu la FlexiRemap®, lomwe liri mu chikhalidwe chowonongeka, limalowa mumayendedwe owerengera okha, ndipo zopempha zonse zolembera zimatumizidwa ku gulu lachiwiri. Njira yodzitetezera yotereyi imaperekedwa kuti ifulumizitse ntchito yomanganso ndikuchepetsa mwayi wa kulephera kwa galimoto ina mkati mwa gulu lomwelo. Si chinsinsi kuti pakumanganso, ma drive onse pagulu amakumana ndi zochulukira chifukwa cha kusokoneza kuwerenga, kulemba, ndi kubwezeretsa magwiridwe antchito pazotsalira zotentha. Izi zimawonjezera mwayi wolephera kuyendetsa galimoto ina. Ndipo ntchito zolembera zambiri, m'pamenenso kumanganso kumatenga nthawi yayitali.
Ntchito yomanganso ikatha ndipo gulu la FlexiRemap® libwerera mwakale, padzakhala skew pang'ono pazolemba pakati pa magulu awiriwa. Chifukwa chake, kuti mufananize, ntchito zolembera zotsatizana nthawi zambiri zimagwera pagulu lobwezeretsedwa (zowona, m'njira yoti machitidwe omaliza samavutika kwambiri).
Sizingatheke kukulitsa magwiridwe antchito a Makina Onse a Flash kutengera ma aligorivimu a RAID pamwamba pa zinthu zina (~ 280K IOPS@4K kulemba mwachisawawa) ngakhale mutagwiritsa ntchito makina osungira ovuta. Tekinoloje ya FlexiRemap®, chifukwa cha njira yosiyana kwambiri yokonzekera malo osungira, sikuti imangogonjetsa chotchinga ichi, komanso nthawi imodzi imawonjezera moyo wautumiki wa ma SSD kangapo. Choncho machitidwe ali ndi zabwino zambiri pakati pa All Flash arrays pamagawo ambiri (IOPS / $, GB / $, TCO, ROI), kuwapangitsa kukhala oyenera maudindo akuluakulu m'malo opangira makasitomala kuti athe kuthana ndi ntchito zofunikira kwambiri.
Source: www.habr.com
