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THOMAS CARRIERO: Ninsab Thomas Carriero.

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Jien inġinier software fuq Dropbox.

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>> ALEX ALLAIN: Ninsab Alex Allain.

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I am inġinier hawn fuq Dropbox.

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>> THOMAS CARRIERO: Iva, I kien
attwalment l-ewwel TF ras għall CS50

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meta David Malin ħadet f'idejha l-klassi.

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I kienet diġà ġiet tagħlim
CS50 għal żewġ semestri

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ma 'Mike Smith, li kien
il-professur qabel hemmhekk.

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>> ALEX ALLAIN: So I attwalment ma
jieħdu CS50, imma jien ma TF darbtejn.

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Ladarba bħala TF regolari,
u mbagħad sena għolja tiegħi

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I kien attwalment TF kap ta '
CS50, li kien ta 'gost.

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THOMAS CARRIERO: So
meta David milħuq barra

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lili dwar it-twaqqif
Dropbox fl-appliance CS50,

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I kien verament eċċitati, minħabba
għandna attwalment jkollu klijent Linux,

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għalhekk ħafna mill-utenti tagħna użu jew
Twieqi jew il-klijenti Macintosh,

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iżda l-Linux, Macintosh, u Windows
klijenti huma kollha attwalment simili ħafna.

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>> Allura dak li għamilna huwa aħna installat minn qabel
il-klijent Dropbox Linux fil-CS50

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appliance, u din tmur bħad
kollha ta 'utenti tagħna oħra Linux.

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>> ALEX ALLAIN: Allura l-
mod Dropbox xogħlijiet huwa

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runs bħala klijent fuq ħafna differenti
sistemi operattivi u apparat.

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Il-klijent desktop Dropbox huwa
wieħed mill-aktar magħrufa sew,

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u waħda mill-aktar interessanti.

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>> THOMAS CARRIERO: So Dropbox
bażikament jieħu l-fajls

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li inti tpoġġi fil-folder u biċċiet
dawk il-fajls fis-biċċiet erba 'megabytes.

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Allura aħna ser tagħti 100-megabyte
Fajl PDF u aħna ser

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chunk fis-25 biċċiet erba 'megabytes.

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Dawk biċċiet huma mbagħad encrypted u
allura aħna jibgħathom lill servers blokk tagħna.

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>> ALEX ALLAIN: Il-servers blokk huma
il-ħażna għall-blokki nfushom,

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u għalhekk kull blokk hija maħżuna fil-
l-server blokk mal-data

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u Shaw 356 hash ta 'dak blokka.

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Li l-encryption bażika ħafna primitive
li tiġbor fil-qosor, f'xi sens,

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id-data b'mod ħafna uniku
li l-uniku għal dak data.

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>> Inti tista 'upload l-
fajl sħiħ kollha f'daqqa,

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iżda jirriżulta jekk inti tagħmel
li, fajls verament kbar jieħu

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żmien twil verament biex ittella, u jekk
għandek falliment, int minn xortih

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u inti għandek terġa 'tibda dan.

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>> Dak li aħna mbagħad nagħmlu huwa we tell
server ieħor fis-sistema tagħna,

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u dak li nsejħu l-metadata
server, li ħej dan huwa fajl,

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u huwa magħmul mill-
lista li ġejja ta 'blokki.

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U aħna rrinunzjati l-hashes
biex tidentifika dawk il-blokki

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minflok uploading-ġdid
il-blokk kollu.

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Il metaserver mbagħad
kontrolli l-servers kbar,

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tiżgura l-blokki qegħdin hemm.

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Jekk huma, perfetta.

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Kollox huwa tajjeb.

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>> THOMAS CARRIERO: Meta aħna
tixtieq li bażikament tniżżel

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l-fajl mill-internet, ejja
jiġifieri, aħna ser ngħidu għall-aħħar metaserver

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ewwel, ħej tista 'tgħidli
dwar fejn tinstab din fajl?

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U metaserver se ngħid, oh tal dan il-fajl
attwalment 25 biċċiet erba 'megabytes,

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u hawn huma.

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U allura aħna ser imorru server blokk u
attwalment tniżżel kull wieħed minn dawk biċċiet.

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U allura aħna ser jirrikostitwixxu
l-fajl minn hemm,

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u allura aħna ser tibda l-download.

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Iva, hekk Dropbox 'jittratta
bi skala bażikament

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billi ħafna, sharding aggressivi ħafna.

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>> ALEX ALLAIN: Sharding huwa meta inti
jieħdu l-utenti fil-bidu tiegħek sa

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jew kumpanija tiegħek u forsi huma
użati biex tkun fid-database waħda,

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u li xogħlijiet kbir sakemm inti
hit ċertu numru ta 'utenti.

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U verament dak li trid
tagħmel hu li ssib xi mod

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li jaqsam dawk madwar żewġ
databases, jew forsi aktar minn tnejn.

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Idealment, biżżejjed li inti tista '
għandhom kull utent fid-dinja.

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>> U hekk meta inti Shard,
dak li għandek tagħmel huwa inti

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issib xi mod biex tiddeċiedi
li database li jmorru

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li li ma tkunx teħtieġ
laqtu direttorju ċentrali.

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Jew forsi huwa malajr ħafna,
cheap direttorju ċentrali ħarsa-up.

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>> THOMAS CARRIERO: Aħna qatt ma jkollhom
kollox maħżuna f'database waħda,

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minħabba li kważi
qatt tmur għall-iskala.

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Allura minflok, dak li se tagħmel huwa li tieħu kollha
dik l-informazzjoni, il-fajls kollha li

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huma maħżuna fuq il-metadata,
Shard madwar l-mijiet

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jew eluf ta 'databases loġiku.

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U dan ifisser li meta għandna
jitlob għall-informazzjoni ta 'utent,

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aħna ser ewwel ngħidu, ħej li database
hija informazzjoni dan l-utent maħżuna fil-?

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Imbagħad aħna ser bażikament
jużaw dik id-deċiżjoni li jmorru

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issib li database
u li fejn aħna ser

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tagħbija l-fajls jew kollha
l-metadata dwar il-fajls.

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>> Allura aħna jużaw ħafna ta 'sharding.

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Iżda sharding mhuwiex dejjem biżżejjed.

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Inti fil-fatt bżonn cache
ħafna tat-talbiet komuni,

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minħabba li, anki dawk database
mistoqsijiet jistgħu jkunu għaljin

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hekk aħna wkoll jagħmlu jinqabad aggressivi
strateġiji biex tiżgura li l-aktar

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talbiet komuni huma
pjuttost faċli biex tiġi kkalkulata.

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U bażikament li jagħmel ħafna
aktar mgħaġġel u jagħmilha taħdem iskala ex.

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Allura dak fuq ħafna
ta 'livell għoli kif Dropbox xogħlijiet.

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>> ALEX ALLAIN: Ninsab Alex Allain.

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>> THOMAS CARRIERO: U
Jien Thomas Carriero.

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ALEX ALLAIN: U dan huwa CS50.

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