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THOMAS Carriero: Mimi Thomas Carriero.

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Mimi nina mhandisi wa programu katika Dropbox.

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>> ALEX Allain: Mimi Alex Allain.

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Mimi ni mhandisi hapa Dropbox.

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>> THOMAS Carriero: Ndiyo, nilikuwa
kweli kwanza kichwa TF kwa CS50

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Daudi Malin alichukua juu ya darasa.

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Nilikuwa tayari kufundisha
CS50 kwa semesters mbili

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na Mike Smith, ambaye alikuwa
profesa kabla ya hapo.

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>> ALEX Allain: Kwa hiyo mimi kwa kweli si
kuchukua CS50, lakini mimi TF ni mara mbili.

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Mara baada ya kama TF mara kwa mara,
na kisha mwaka wangu wa mwandamizi

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Mimi kwa kweli kichwa TF ya
CS50, ambayo ilikuwa mengi ya furaha.

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THOMAS Carriero: Hivyo
Daudi kufikiwa nje

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na mimi kuhusu kuanzisha
Dropbox katika CS50 appliance,

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Mimi kwa kweli nilikuwa msisimko, kwa sababu
sisi kweli kuwa Linux mteja,

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hivyo wengi wa watumiaji wetu kutumia aidha
Windows au wateja Macintosh,

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lakini Linux, Macintosh, na Windows
wateja wote ni kweli sawa sana.

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>> Hivyo tulichokifanya ni sisi kabla ya imewekwa
Dropbox Linux mteja katika CS50

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appliance, na anaendesha tu kama
yetu yote ya watumiaji wengine Linux.

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>> ALEX Allain: Hivyo
njia Dropbox kazi ni

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anaendesha kama mteja juu ya mbalimbali
mifumo ya uendeshaji na vifaa.

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Dropbox desktop mteja ni
mmoja wa watu wengi maalumu,

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na moja ya kuvutia zaidi.

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>> THOMAS Carriero: Kwa hiyo Dropbox
kimsingi inachukua mafaili yote

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kwamba kuweka katika folder na chunks
files wale katika nne megabyte chunks.

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Hivyo tutaweza kuchukua 100 megabyte
PDF file na tutaweza

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chunk ndani 25 nne megabyte chunks.

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Wale chunks ni basi encrypted na
kisha sisi kuwatuma kuzuia yetu server.

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>> ALEX Allain: watumishi kuzuia ni
kuhifadhi kwa ajili ya vitalu wenyewe,

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na hivyo kuzuia kila ni kuhifadhiwa katika
kuzuia server na data

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na Shaw 356 hash ya kuzuia hiyo.

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Hiyo ni encryption ya msingi sana primitive
kuwa muhtasari wa, katika baadhi ya akili,

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data kwa njia ya kipekee sana
kwamba ya kipekee kwa data hiyo.

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>> Unaweza kupakia
file zima wote kwa mara moja,

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lakini zinageuka kama wewe kufanya
kwamba, kwa kweli kubwa files kuchukua

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kweli kwa muda mrefu kupakia, na kama
una kushindwa, wewe ni nje ya bahati

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na una upya yake.

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>> Nini sisi basi ni sisi tunasema
server nyingine katika mfumo wetu,

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na kile tunachokiita metadata
server, kwamba hey hii ni faili,

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na ni linajumuisha
zifuatazo orodha ya vitalu.

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Na sisi kupita juu hashes
kutambua vitalu wale

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badala ya re-kuweka
kuzuia nzima.

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metaserver kisha
hundi ya kuzuia watumishi,

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hufanya uhakika vitalu ni huko.

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Kama wao ni, kamilifu.

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Kila kitu ni nzuri.

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>> THOMAS Carriero: Wakati sisi
wanataka kimsingi kushusha

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file kutoka katika mtandao, hebu
kusema, tutaweza kusema kwa metaserver mwisho

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kwanza, hey unaweza kuniambia
kuhusu ambapo iko file huyu?

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Na metaserver watasema, oh file huu
kweli 25 nne megabyte chunks,

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na hapa ni.

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Na kisha tutaweza kwenda kuzuia server na
kweli kushusha kila chunks hizo.

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Na kisha tutaweza upya
file kutoka huko,

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na kisha tutaweza kuanza download.

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Ndiyo, hivyo Dropbox ya mikataba
na wadogo kimsingi

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na sana, sharding fujo sana.

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>> ALEX Allain: Sharding ni wakati
kuchukua yote ya watumiaji katika kuanza yako up

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au kampuni yako na labda wao
kutumika kuwa katika orodha ya moja,

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na kwamba kazi kubwa mpaka
hit idadi fulani ya watumiaji.

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Na kwa kweli nini unataka
kufanya ni kutafuta baadhi ya njia

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kugawa wale katika mbili
database, au labda zaidi ya miaka miwili.

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Kusema ukweli, kutosha kwamba unaweza
na kila user katika dunia.

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>> Na hivyo wakati wewe Shard,
nini kufanya ni wewe

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kutafuta baadhi ya njia ya kuamua
ambayo database kwenda

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kwa hauhitaji
kupiga directory ya kati.

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Au labda ni haraka sana,
nafuu kuangalia-up directory ya kati.

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>> THOMAS Carriero: Sisi kamwe kuwa
kila kitu kuhifadhiwa katika database moja,

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kwa sababu hiyo karibu
kamwe kwenda wadogo.

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Hivyo badala yake, nini sisi kufanya ni kuchukua kila
kwamba habari, files yote

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ni kuhifadhiwa kwenye metadata,
kigae katika mamia

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au maelfu ya database mantiki.

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Na hiyo ina maana kwamba wakati tuna
kuomba kwa habari ya mtumiaji,

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tutaweza kusema kwanza, hey ambayo database
ni habari mtumiaji huyu kuhifadhiwa katika?

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Basi tutaweza kimsingi
kutumia uamuzi huo kwenda

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kujua kwamba database
na hapo ndipo tutaweza

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mzigo mafaili yote au yote
metadata kuhusu files.

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>> Hivyo sisi matumizi mengi ya sharding.

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Lakini sharding haitoshi daima.

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Wewe ni kweli haja ya cache
mengi ya maombi ya kawaida,

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kwa sababu hata wale database
maswali inaweza kuwa ghali

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hivyo sisi pia kufanya ukamataji fujo
mikakati ya kuhakikisha kwamba wengi

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maombi ya kawaida ni
rahisi kabisa compute.

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Na kimsingi kwamba inafanya mengi
kasi na inafanya kazi wa zamani wadogo.

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Hivyo kwamba ni katika sana
kiwango cha juu cha jinsi Dropbox kazi.

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>> ALEX Allain: Mimi Alex Allain.

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>> THOMAS Carriero: Na
Mimi nina Thomas Carriero.

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ALEX Allain: Na hii ni CS50.

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