Tri Kesh Laya Bitwin Sɛlekt ɛn Disk

Ki Insayt: Insay bɔku OLTP woklɔd dɛn, wan wɛl-sayz bafa pul min se 95–99% pan ɔl di data rid dɛn de sav frɔm RAM. Di wok sɛt — di sabsɛt fɔ yu data we kwɛstyɔn dɛn kin rili tɔch bɔku tɛm — bɔku tɛm i kin smɔl fa fawe pas di ɔl di database saiz. Sayz yu bafa pul fɔ fit yu wok sɛt, nɔto yu ɔl datasɛt, na di singl ays-ritɔn tuning akshɔn we yu kin tek.

Aw di Ɔpreshɔn Sistem Kesh De Fil di Gap Bitwin RAM ɛn Disk?

Ivin we di database in yon bafa pul mis, wan kwɛstyɔn nɔ de yet fɔ wan tru disk rid. Di ɔpreshɔn sistɛm de mentɛn wan pej kesh (dɛn kin kɔl am bak di faylsistim kesh), wan rijyɔn we gɛt RAM we dɛn de manej wit kɛnal we de bafa rid ɛn rayt to blɔk divays dɛn. We di database injin aks fɔ pej we nɔ de na in bafa pul, di OS kɛnal de chɛk in yon pej kesh bifo i gi fizik I/O kɔmand to di stɔrɔj kɔntrol.

Dis tɔd layt na big wan we di aplikeshɔn divɛlɔpa dɛn nɔ de si bɔt i impɔtant pasmak pan sistɛm dɛn usay di database bafa pul nɔ de ɔnda-prɔvishɔn. Di OS pej kesh de sheb akɔdin to ɔl di prɔses dɛn, so i de kɔmpit wit yu aplikeshɔn sava, wɛb sava, ɛn ɛni ɔda softwe we de rɔn na di sem ɔs. Na dediket database sava, dis kɔmpitishɔn nɔ bɔku, ɛn di OS kesh de gi wan mininful sɛkɔn-chans bafa. Na shered host ɔ kɔntena wit tayt mɛmori limit, di OS kesh kin tu smɔl bɔku tɛm fɔ ɛp.

Us Kesh Laya Rispɔnsibul fɔ di Mɔs Pɔfɔmɛnshɔn Win insay Praktis?

In rial-wɔl prodakshɔn sistɛm, di bafa pul de domin di pefɔmɛns autkam bay wan big margin. Na dis mek ɛni layt de kɔntribyut difrɛn we akɔdin to yus kes dɛm:

we dɛn kɔl
• Kwɛri rizɔlt kesh: Ays bɛnifit pan rid-hɛvi, mɔst statik datasɛt — ripɔt kwɛstyɔn, kesh dɛshbɔd, pɔblik kɔntinyu ɛndpɔynt. Yuzlɛs pan tebul dɛn we gɛt rayt.
• Database bafa pul: Di yunivasal wok ɔs. Ɛvri prodakshɔn database sava fɔ tun ya fɔs. I de handle ɔl tu di random ɛn sikwinshal akses patɛn fayn fayn wan.
• OS pej kesh: De gi sef net we di bafa pul nɔ saiz. I de ɛp bak bɔku bɔku wan we dɛn de skan big tebul dɛn we ɔda we go pul ɔt pej dɛn kɔmɔt na di bafa pul.
• Stɔrej kɔntrol kesh (hadwɔd layt): Wan nɔmba 4 layt, we dɛn kin ɔverluk bɔku tɛm — NVMe SSD ɛn RAID kɔntrol dɛn kin mentɛn onbɔd rayt kesh wit bateri ɔ kapasitɔ bak-ap. Dis de protɛkt durabiliti witout sakrifays rayt thruput pan di ɛkspɛns fɔ fsync latɛns.
• Aplikeshɔn-layer kesh (Redis, Memcached): I de sidɔm ɔp di database ɔltogɛda, i de kech siriɔs kwɛstyɔn rizɔlt ɔ kɔmpyuta ɔbjɛkt fɔ avɔyd fɔ hit di database atɔl — i fayn fɔ mɔlti-tɛnant SaaS pletfɔm dɛn we de sav tawzin kɔnkɔrɛnt yuza dɛn.

Aw Mɔdan Biznɛs Plɛtfɔm dɛn Go Leva Kesh Akitekchɔ fɔ Rilaybiliti na Skel?

Fɔ biznɛs dɛn we de wok akɔdin to bɔku fɛnshɔnal mɔdyul dɛn — CRM, prɔjek manejmɛnt, i-kɔmrɛs, analitiks — kesh akitɛkɛt de disayd dairekt wan fɔ di pletfɔm rispɔnsivnɛs as tim dɛn de gro. Plɛtfɔm dɛn we dɛn bil pan wan wɛl-layer kesh strateji kin sav tɛn tawzin kɔnkɔrɛnt yuza dɛn we nɔ gɛt prɔpɔshɔnal infrastukchɔ kɔst. Di ki na fɔ disayn data akses patɛn we de rɛspɛkt kesh bɔda: kip hot data smɔl ɛn akses patɛn prɛdiktibɛl, yuz rid riplik fɔ distribyushɔn bafa pul lod, ɛn posishun wan aplikeshɔn-layer kesh lɛk Redis bifo di database fɔ ɛndpɔynt dɛn we de sav di sem data to bɔku yuza dɛn wan tɛm.

Mewayz na akitɔk wit ɛksaktɔli dis filɔsofi na in maynd. Wit 207 intagreted biznɛs modul dɛm we de pawa ova 138,000 yuza dɛm, di pletfɔm in data layt de disayn so dat di ɔvawɛl majoriti fɔ rid dɛn de sav frɔm kesh — kip rispɔns tɛm fast ɛn infrastukchɔ kɔst prɛdiktibɛl if yu de rɔn pan di $19/mɔnt stata plan ɔ di $49/mɔnt pɔshɔnal taya.

Kwɛshɔn dɛn we dɛn kin aks bɔku tɛm

Fɔ disable di kwɛstyɔn kesh kin mek di database wok fayn ɔltɛm?

Nɔto ɔltɛm, bɔt fɔ rayt-hɛvi woklɔd i tipikul fɔ du. Di kwɛstyɔn kesh nid fɔ gɛt wan glob ɔl mutɛks fɔ mek i kɔntinyu fɔ kɔnsistɛns, we kin bi bɔtulnɛk ɔnda ay kɔnkɔrɛns. MySQL 8.0 bin pul di kwɛstyɔn kesh ɔltogɛda fɔ dis rizin. PostgreSQL nɔ ɛva impruv wan bilt-in kwɛstyɔn kesh, i bin abop insted pan di bafa pul ɛn aplikeshɔn-layer kesh. If yu rid-to-rayt ratio ay ɛn yu kwɛstyɔn dɛn rili ripit, wan kwɛstyɔn kesh kin gi rial bɛnifit — ɔdasay, invɛst da tyuning ɛfɔt de na di bafa pul.

Aw a go no if mi bafa pul saiz kɔrɛkt?

Monitor yu bafa pul hit ratio: di pasɛnt fɔ pej rikwest dɛn we dɛn de sav frɔm di pul versus di wan dɛn we nid fɔ rid disk. Hit ratio we de dɔŋ 95% pan OLTP woklɔd na signal fɔ inkrisayz pul saiz. Insay MySQL, aks SHOW ENGINE INNODB STATUS ɛn luk di bafa pul hit rit. Insay PostgreSQL, di pg_statio_user_tables view de ɛksplɔz hip blɔk dɛn we dɛn rid frɔm disk versus we dɛn sav frɔm di bafa pul. Aim fɔ kip yu ɔl wok sɛt — nɔto yu ful datasɛt — rɛsidɛnt na RAM.

Wetin na di rilayshɔn bitwin kesh layt ɛn mɔlti-tɛnant SaaS rilaybiliti?

Insay mɔlti-tɛnant SaaS, kesh layers de mek "nɔys neba" prɔblɛm dɛn we wan tɛnant in ebi kwɛstyɔn lod de pwɛl di pefɔmɛns fɔ ɔl di ɔda tɛnant dɛn. Tenant-aware aplikeshɔn kesh wit TTL-based invalidation de kip per-tenant hot data in Redis, drastikli ridyus bafa pul prɛshɔn frɔm big akɔn. Database-level kɔnɛkshɔn pul we dɛn jɔyn wit wan wam bafa pul de mek shɔ se burst aktiviti frɔm ɛni singl akɔn nɔ de flush shered pej dɛn frɔm kesh ɛn mek latɛns spayk akɔdin to di pletfɔm.

Kesh layers nɔto database trivia — na di akitekchral fawndeshɔn we de separet pletfɔm dɛn we de de fast na skel frɔm di wan dɛn we nid fɔ kɔnstant infrastukchɔ fayafayt. If yu de bil ɔ rul wan biznɛs we nid wan pletfɔm we dɛn dɔn ɔlrɛdi ɔptimayz fɔ dɛn rialiti ya, ɛksplɔrɔ Mewayz na app.mewayz.com — 207 modul, wan kɔrɛkt pletfɔm, we dɛn bil fɔ pefɔm rili frɔm yu fɔs yuza to yu ɔndrɛd-tawzin.