MFS: an Adaptive Distributed File System for Mobile Hosts

Transcription

1 MFS: Aptiv Distribut Fil Sstm fr Mbil Hsts Bjmi Atki Kth P Birm Dprtmt f Cmputr Scic Crll Uivrsit, Ithc, NY Abstrct Mbilit is criticl ftur f cmputr sstms, whil wirlss twrks r cmm, mst pplictis tht ru mbil hsts lck flibl mchisms fr t ccss i virmt with lr frut vritis i twrk cctivit Such citis ris, fr mpl, i cllbrtiv wrk pplictis, prticulrl wh wirlss wir usrs shr fils r tbss I this ppr, w scrib sm tchius fr pti t ccss t twrk vribilit i th ctt f MFS, clit cch mr fr istribut fil sstm W shw hw MFS is bl t pt t wil vri bwith lvls thruh th us f mlss ptti, vlut th bfit f mchisms fr imprvi fil sstm prfrmc cch csistc usi micrbchmrks fil sstm trcs Itructi Mbilit is w mjr ftur f cmputr sstms: vr th pst c, lptps h-hl vics cpbl f wirlss twrk ccss hv bcm cmm, wirlss twrks r ls prlifrti Applictis tht ru hsts i wirlss twrks must cp with cstrits ccss t t tht r rll t prst i wir twrks Distc frm bs stti, ctti with thr hsts r prcsss th sm hst, itrfrc, switchi btw iffrt wirlss mi ll cmpu th vribilit i twrk prfrmc t which pplictis must pt if th r t prfrm wll This ppr fcuss ptti tchius fr mmt f t ccss mifi b mbil hsts W ivstit ptti i th ctt f MFS, clit cch mr fr istribut fil sstm W cctrt istribut fil sstms bcus sstms i this r r hihl vlp hv wll urst smtics, lthuh th tchius w scrib shul b brl pplicbl i thr pplicti virmts, such s cchi mic Itrt ctt r cchi t imprv th prfrmc f itrctis with wb srvics W vlut Th uthrs wr supprt i prt b DARPA ur AFRL rt RADC F-99--, b AFOSR ur MURI rt F9---, with itil supprt frm Micrsft Rsrch frm th Itl Crprti MFS usi fil ccss trcs frm Wiws NT Ui, sthtic wrkl si t mult shri pttrs s i cllbrtiv iri sstms Eisti wrk i cch mmt fr mbil fil sstms,,, ] icrprts mchisms fr mki fficit us f vilbl bwith Hwvr, it hs mstl fcus pti isti sstms t cp with pris f lw bwith, i stl which w will rfr t s ml ptti Wh bwith is hih, th pplicti cmmuicts rmll; wh bwith flls blw thrshl, th pplicti trs lwbwith m i which cmmuicti is rstrict r frr Mr rll, pplicti hs smll umbr f pssibl ms chss th pprprit bs th currtl vilbl bwith Fr mpl, i th C fil sstm ], th cch mr prts i ithr strlcct, wkl-cct, r iscct m, which ffcts th plic fr writi chs t fils bck t th srvr Ml ptti schms r wll-suit t virmts i which chs i bwith r rltivl prictbl, such s switchi twrk ccss frm Ethrt t mm, but t s pprprit i fr wirlss twrks, i which bwith vilbilit is lss prictbl vris vr lrr pssibl r Th ti f isufficit bwith c vr pi hw much t th pplicti is tri t s, s tht it m mk ss t just twrk us wh th bwith rps b hlf, rthr th just wh it flls t mm-lik lvls Slcti m ccri t th vilbl bwith c ucssril cstri cmmuicti, sic it irs wht t th pplicti ctull wts t s vr th twrk Dfrri writi bck ll mifictis t fils m t b ssibl plic if ths r th l msss vilbl t s W scrib MFS Mbil Fil Sstm), flibl cch mr fr istribut fil sstm clit, which iffrs frm tritil cch mr si i tw imprtt rspcts First, MFS uss RPC librr supprti priritis t bl mlss ptti ], which llcts vilbl bwith bs th tps f msss bi st B ssii priritis pprpritl, frru ctivitis, such s rtrivi fils, c prc ccurrtl with bckru ctivitis such s writi bck chs, ur th ssurc tht if bwith bcms scrc, th bckru ctivitis, rthr th th frru s,

2 will b plis first Mlss ptti usi priritis cmmuicti ls llws MFS t b mr flibl i rsps t bwith vritis th wul b pssibl with ml schm Sc, MFS icrprts w cch csistc lrithm t fficitl prvi hih r f csistc fr ccss t shr fils, which is ruir fr cllbrtiv wrk pplictis Th rst f this ppr is ris s fllws: Scti scribs th MFS si iffrcs frm isti istribut mbil fil sstms, s wll s ivi vrviw f th MFS RPC librr Scti scribs th us f priritis cmmuicti i MFS primts t vlut its ffctivss Scti prsts plis primtl rsults fr th MFS i mchism, Scti s th sm fr th cch csistc lrithm Fill, Scti cclus scribs futur wrk MFS vrviw MFS iffrs frm rlir mbil fil sstms i justi t chi twrk citis usi mlss ptti It cmpriss cr clit-srvr fil sstm, umbr f subsstms tht prfrm iffrt kis f ptti, c b slctivl bl Fiur shws th structur f th sstm I this scti w scrib th cr sstm, whil subsut sctis th sm fr th thr mi subsstms W bi with vrviw f mbil fil sstm si th rlti f MFS t prvius wrk, th brifl scrib th ptiv RPC librr us i MFS, th currt MFS implmtti MFS si rlt wrk Th cr f MFS fllws si cmm t m mbil fil sstms,,, ], which us tchius such s whlfil cchi, upt li cmbi with schrus writs, t cp with iscctis r itrmittt cctivit Th si f MFS is clsst i structur t tht f C ] th Lw-Bwith Fil Sstm LBFS) ] A hst cti s clit f MFS fil sstm rus usr-lvl cch mr, which rcivs fil sstm prtis itrcpt b krl mul, itrcti with th VFS lr f th lcl fil sstm W pt th sm pprch t itrcpti VFS prtis s LBFS, mki us f th krl mul prvi s prt f th Arl AFS clit ] Th cch mr mitis cch f rctl-ccss MFS fils th lcl isk Wh VFS prti is itrcpt fr fil tht is t i th cch, it is rtriv i full frm th pprprit srvr, th VFS prti is th rsum MFS uss th writbck--cls smtics first implmt i th Arw Fil Sstm ] Wh irt fil is cls, th tir fil ctts r trsfrr t th srvr Th LBFS chuk Thuh MFS is si t supprt multipl MFS fil srvrs, i this ppr Applicti prrms MFS cch mr bckru prcssi cch csistc ccss mitri uti trffic upt li icmi trffic m ftch schrus writbck schrus writbck Aptiv RPC librr MFS srvr Fiur : MFS rchitctur Th mst imprtt prt f MFS is th cch mr, which itrcpts fil sstm prtis frm pplicti prrms rslvs thm it ccsss t its lcl MFS cch r RPCs t srvr Th cch mr hs umbr f cmpts: ths i sli bs r prt f th cr sstm, ths i sh bs r ptil tsis which r scrib i subsut sctis schm fr miimisi bwith utilisti wh trsfrri fils is t us i MFS, lthuh it is rthl t MFS ptti cul b t furthr imprv prfrmc Th srvr tht strs fil is rspsibl fr mitii th mutul csistc f th cpis cch b clits It rcrs which clits cch th fil, is rspsibl fr tifi thm f chs MFS implmts vriti f th schm us b C: wh fil is rtriv frm th srvr, th srvr issus limit-urti cllbck prmis, blii it t ifrm th clit thruh cllbck if thr hst mifis th fil If th cllbck prmis pirs withut cllbck bi issu, th clit must rvlit th fil bfr usi it Th cch csistc lrithm is scrib i mr til i Scti Aptiv RPC librr Th fumtl iffrc btw MFS thr fil sstms w hv scrib is i th cmmuicti btw th cch mr srvrs Whil LBFS uss vrit f th NFS RPC prtcl ], MFS, lik C, uss custmis RPC Hwvr, ulik C s RPC, th RPC us i MFS icrprts vl fturs t llw it t pt t twrk vribilit Th MFS RPC librr is implmt tp f th Aptiv Trsprt Prtcl ATP) I iscussi MFS RPC, w iv vrviw f th prts f ATP which r mst rlvt t MFS; ATP its si mtivtis hv b scrib i mr til i ur rlir wrk ] Th hpthsis urli ATP is tht pti t twrk vriti b structuri pplictis ccri t ms is t lws pprprit, c smtims l t pr prfrmc Fiur shws th rsults f primt i which mlss ptti vr ATP chivs hihr bwith utilisti th w will cctrt sstm with sil srvr

3 Ml ptti tru bwith bwith us Mlss ptti tru bwith bwith us tim s) tim s) Fiur : Ml vrsus mlss ptti with ATP Th lft rph shws prfrmc with ml ptti, th riht rph shws schm i which thr r fur clsss f msss bi st simultusl, f icrsi priritis th lwst li crrsps t th hihst pririt) Drk hritl lis rprst prti ms th lft, th hihst pririt f t bi st uri sc th riht Th mlss schm chivs hihr utilisti MB f t st) bcus it lws hs msss t s, whil th ml schm is pt rpi ccurt stimt f th vilbl bwith i rr t slct its crrct prti m MB st) Ths rphs r rpruc frm ] uivlt ml schm Othr primts hv shw tht mlss ptti c chiv imprvmts f - i bwith utilisti, it is pssibl t cstruct css i which th imprvmt is v rtr Wrk ptti i mbil fil sstms hs rll rli ml schms, ], but ur vluti f ATP mstrt tht it cul ls imprv th prfrmc f fil sstm-lik wrkls W iscuss th implmtti f mlss ptti i MFS furthr i Scti ATP is implmt t usr lvl, tp f krl UDP It hs mss-rit itrfc fr cmmuicti, i which msss f rbitrr si c b rlibl trsmitt with thir buris prsrv t th rcivr s si A pplicti c s mss schrusl r schrusl I th lttr cs th sr prvis fucti t b cut wh trsmissi f th mss cmplts, th s prti itslf is -blcki; this is similr t th Quu RPC vlp fr Rvr ] Ulik Quu RPC, ATP ls llws th sr t ttch pririt t ch mss, t ctrl th rr i which th uu msss r trsmitt Msss r uu t th sr ccri t thir rcivrs, ch uu is rr b pririt Msss f th sm pririt withi uu r trsmitt i first-i, first-ut rr ATP ls llws sr t spcif s timut fr mss, which cuss th trsmissi t b susp if it pirs, s tht th sr c rct t it A lus mchism is vilbl fr rciv prtis Bsis tcti wh rmt hst is iccssibl, s timuts t pl mjr rl i MFS A itil us fr timuts wul b t tct s which r t mki prrss rissu fr iffrt fil s Scti ) ATP miistrs priritis b rivi stimt fr th bwith vilbl btw th sr rcivr I rr t miimis th trsmissi l wh w mss is st, ATP uss frm f rt-bs flw ctrl Ech sc is ivi it twt s pris f milliscs urti, t mst -twtith f th vilbl bwith is us uri sil s pri Withut such cstrit, ATP wul s s much t s it cul rcipt f lw-pririt mss, this t cul th b buffr t itrmit lik, li th trsmissi f hih-pririt mss which miht b st ltr Th isvt f this schm is tht hv ctti t th sr m l w mss b s much s milliscs, rrlss f its pririt This ifficic f th ATP implmtti is mst visibl wh thr is ctti btw iffrt priritis t hih bwith MFS implmtti Th vrsi f MFS scrib i this ppr is implmt i C rus FrBSD Bth th clit srvr hv multipl thrs t cp with simultus fil sstm rusts, th RPC librr hs its w thr: thrfr thr r tw mtr thr ctt switchs mss s r rciv prti As w shll scrib i subsut sctis, sm subsstms hv itil thrs t crr ut bckru prcssi Ulss t thrwis, ur primts wr cuct with fult clit cch si f MB RPCs with priritis MFS RPCs r implmt tp f ATP i th turl w: RPC rust cstituts mss, its rpl thr Priritis r us t iffrtit tps f RPCs t imprv prfrmc: i rl, smll RPCs, r ths which wul cus itrctiv clit t blck, r iv hih pririt RPCs fr bckru ctivitis, such s writi bck fils t th srvr, r i fils, r prfrm t lw pririt, s tht th t slw w hih-pririt RPCs Tbl shws th pririt lvls fr iffrt tps f RPCs Assii priritis t RPCs llws MFS t pt t bwith vriti i strihtfrwr w At hih bwiths, ll RPCs cmplt uickl, with r withut priritis As bwith

4 pririt lvl crrspi RPC tps scti VALIDATE hih) ftch ttributs, cllbcks FETCH ftch fil t, irctr ctts STORE-ATTR writ bck irctr mtt upts STORE-FAST writ bck shr fils STORE-DATA writ bck ushr fils PREFETCH lw) fil t Tbl : Pririt lvls fr MFS RPCs Smblic ms r iv fr th pririt lvls, list frm hihst t lwst pririt Th thir clum ivs th scti i which th crrspi RPC tps r scrib i til crss, implmtti withut priritis will rsult i th cmplti tims fr ll RPCs icrsi uifrml Wh priritis r us, bckl f lw-pririt RPCs will ccumult, whil th tim tk fr hih-pririt RPCs t cmplt will icrs mr rull Our si is bs th ssumpti tht wh bwith is lw, ssimt f iffrtit priritis will imprv th rsps tims fr itrctiv tsks If tsk which prmitl prfrms rs cuts i prlll t tsk which prfrms m writs, th with priritis, th first tsk will rciv hihr shr f th bwith I prctic, m pplictis hv pttrs f itrctiv fil ccss ivlvi bth rs writs Fr istc, cmpili surc fils ivlvs itrsprs rs writs, but s t issu ccurrt RPCs frutl Such pplicti will hv imprv r prfrmc wh thr is ctti with thr pplictis, but will crrspil b plis writs This s t mtch ur si l f hvi itrctiv, mstl-r pplictis bti lrr shr f bwith W hv implmt tw slutis t this prblm, bs mki writs schrus: upt li, us i svrl isti sstms icrprt i MFS fr th purpss f cmpris, schrus writbck, which is w t MFS A ltrtiv pprch is t rti schrus writs, but ssi priritis ccri t sm ti f rltiv imprtc f prcsss Ufrtutl, isti prti sstms pplictis rll t prvi this ifrmti, s w hv t ivstit it furthr Upt li Upt li, which is implmt i sm mbil fil sstms tbl C ] Littl Wrk ]), rmvs th ruirmt tht prcsss wit fr writs Rthr th si upt t th srvr s s s fil is cls, th cch mr ls th upt priicll flushs l upts t th srvr Ths sstms bl li wh bwith is lw, t imprv r prfrmc ruc writ trffic b rti upts t th sm fil i th l bfr th r trsmitt Upt li sprts cmmuicti with th srvr it tw istict strms: upts t fils irctris, ll thr trffic Ths tw tps f cmmuicti r schul iptl m cmpt Hwvr, b mki writs schrus, upt li pushs r-writ ctti it th futur, t ccur t th t l flush Th sirs f Littl Wrk icrprt lw-lvl pririt mchism t th IP pckt lvl t furthr ruc itrfrc btw writbck trffic thr twrk trffic st b th clit ] Aschrus writbck Thuh it rucs bwith csumpti, upt li is fumtll usuitbl fr us t hih bwith, sic it impss l trsmitti upts t th srvr Sstms usi upt li must thrfr switch t schrus writs wh bwith is hih, with thrshl ctrlli switchs btw th tw ms Th m switch ls chs th smtics f th fil sstm, th vlprs f C hv t tht utct m chs c surpris th usr i usirbl ws ], such s cch icsistcis risi u t upctl l writs Rthr th rli ml ptti schm icrprti trsiti t upt li wh bwith is lw, MFS uss mlss schrus writbck mchism, which is ctiv t ll bwith lvls Just s with upt li, wh pplicti prfrms prti tht chs fil, such s writ r mtt upt crt, lt, crt irctr s ), it rturs immitl Th upt is th pss t th writbck subsstm, which ss it t th srvr wh thr is sufficit bwith: schrus writbck thrfr l ls upts wh thr is frru trffic Wh bwith is hih, th prfrmc f schrus writbck shul b cmprbl t purl schrus writs, but wh bwith is isufficit, schrus writs will imprv th prfrmc -upt RPCs Th cch mr s writbck thr ivis upts it mtt prtis, such s irctr mifictis fil sttus chs, fil writs Th tw tps f prtis r uu rpl t th srvr sprtl, s tht mtt RPC c prc i prlll with fil writbck Wh RPC frm prticulr uu cmplts, w s tht th upt hs b cmmitt t th srvr Th t upt is th uu schrus RPC fr it is iitit Sprti th smll mtt RPCs frm fil writs llws rmt clits t s sttus chs t fils withut hvi t wit fr itrvi writbck trffic A similr mtivti urlis th cch csistc schm fr hih r-writ ctti virmts w scrib i Scti Th chif cmplit i implmti schrus writbck lis i rslvi pcis btw mtt prtis upts t th sm fil Fr istc, fil m b crt, mifi cls, th lth f th mtt uu m b uh t m tht th fil upt wul b iitit first: i this cs th fil upt must wit Altrtivl, fil m b

5 tst ctivit schrus li schrus uifrm priritis uifrm priritis uifrm priritis GC rp 9 ) ) ) ) ) ) cmpil ) 9) ) 9) ) ) GW rp 9 ) 9 ) ) ) ) ) writ ) ) ) ) ) ) RC r 9 ) 9 9) ) ) ) 9 ) cmpil ) ) ) ) 9 ) ) RW r ) ) ) ) ) ) writ ) ) ) ) ) ) Tbl : Prfrmc f MFS priritis writbck schms Ech tst csists f tw ccurrt prcsss cuti iffrt wrkls M tims t cmplti r shw with str vitis, vr t cutis Thr iffrt plicis fr writi bck fils r list, ur uifrm r iffrtit priritis rs tk prcc vr writs) Vlus i bl r f prticulr siificc Nt tht lps tims fr writ wrkls iv th tim util th prcss rui th wrkl fiishs, t wh th l is flush this is shw i Fiur ) mifi th lt, which ruirs th fil upt RPC t b ccll if it is still i trsmissi wh th rmv RPC is iitit A upt t fil will suprs prvius uu upts Prfrmc vluti Aftr i priritis t RPCs, it is turl t sk wh th r bficil, t wht r I iti t cmpri MFS with withut priritis RPCs, w ls ivstit th prfrmc impct f rplci schrus RPCs fr fil upts with schrus writbck Th prfrmc f ths ltrtivs is cmpr i st f micrbchmrks, with wrkls thr frm Wiws NT fil sstm trcs Our primtl stup csists f tw GH Ptium III sktp mchis rui th FrBSD prti sstm, f which cts s MFS srvr, th thr s MFS clit Th clit mchi mks us f th Dummt trfficshpi mul i FrBSD t limit its icmi uti bwith Th primts w cuct i this scti hv cstt bwith vr th urti f th primt, but w ls th prfrmc f MFS wh th bwith vris vr th curs f primt i Scti Micrbchmrks Th first st f primts cmprs iffrt MFS cfiurtis fr spcific tps f ctti Fur wrkls wr us: Grp: cuts th rp utilit svrl tims ch f - KB fils Th fils r prst i th cch, but must b vlit bfr th r us R: ccsss -MB fils i suc, writi th ctts f ch fil t vull Th fils r t iitill prst i th cch Writ: cpis -MB fils frm th lcl fil sstm it th MFS fil sstm Cmpil: cmpils th tir MFS fil sstm its RPC librr 9 fils irctris cmprisi KB) N f th fils r iitill i th cch This wrkl prfrms itsiv pttr f rs writs fils withut risi th issu f ccurrt ccsss tpic w tckl i Scti ) Of ths wrkls, w clssifi Grp R s frru wrkls, Cmpil Writ s bckru wrkls Fur cmbi wrkls wr th rt b rui frru bckru wrkl ccurrtl: w t ths s GC GrpCmpil), GW GrpWrit), RC RCmpil) RW RWrit) Thr tps f RPCs prmit: cch vlitis, ftchs f fil t, str prtis fr fils, i sci rr f pririt Th im f th primts ws t mstrt tht priritis imprv th prfrmc f th frru wrkls Th fur cmbi wrkls wr cut tp f MFS cfiur with ithr schrus writs, upt li r schrus writbck Th upt li mchism ws cfiur t l flushi upt fr t lst sc Evr primt ws rpt t tims t ch f fiv pssibl bwith vlus Tbl shws th tim tk fr ch wrkl t bwith f KBs, Fiur shws vrll rsults fr slct cfiurtis Th rsults i Tbl mstrt th bfit f priritis wh thr is hih ctti btw hih-pririt RPCs writs I bth th IO-bu GW RW wrkls, i priritis crss th tim ruir fr th frru wrkl t cut, b up t s lps tims fr RW-r with schrus writs i th tbl) This is prticulrl tru i th RW tst, whr th frru wrkl rts hv ctti b ftchi lr vlum f t Th rtst bfits r bsrvbl fr th cmbiti f schrus writs with priritis, sic hr th prfrmc f th bckru wrkl c ls imprv b t hvi t wit fr its writs t b cmmitt t th srvr I th GC RC tsts, whr thr is lihtr ctti, th impct f priritis is liibl, i sm css rsults i sliht vrh, but this is chifl

6 uifrm priritis sc GC tst rp) ) GC tst GC tst cmpil) uifrm priritis sc uifrm priritis sc GW tst rp) b) GW tst uifrm priritis sc GW tst writ) uifrm priritis sc RC tst r) 9 RC tst cmpil) uifrm priritis sc uifrm priritis sc RW tst r) uifrm priritis sc RW tst writ) c) RC tst ) RW tst Fiur : Prfrmc f priritis RPC with rspct t bwith vriti Ech pir f rphs i shws th spup f f thr cch mr cfiurtis, rltiv t th tim tk b uifrm priritis with schrus RPCs t KBs As wll s uifrm priritis schrus RPCs uifrm ), th rphs ls shw curvs fr iffrtit priritis schrus RPCs priritis ) iffrtit priritis schrus RPCs sc ) Th vlus pltt fr bwith f KBs r th sm s shw i Tbl u t th vrh f priritis fr smll RPCs mti i Scti Cmpri th cuti tim f th frru wrkls with schrus writs, upt li schrus writbck rvls tht th lttr tw ptis rll prfrm cmprbl t r bttr th schrus writs Li schrus writbck rtl imprv th prfrmc f th bckru wrkls, s hs b t prviusl, ] W fcus MFS with schrus writbck i th rst f this ppr bcus it prvis cmprbl prfrmc t l upts, llws strihtfrwr mlss ptti t bwith vriti, is sil tsibl t mr th lvl f pririt, which is ruir fr ur cch csistc lrithm Sic ruci vilbl bwith icrss th ctti btw RPCs f iffrt tps, th bfits f RPC priritis shul b mr pprt t lwr priritis Fiur shws th primts f Tbl t t wir r f bwith vlus I ths ltr primts, w vlut MFS prfrmc with bwiths frm t KBs: whil KBs is t lw i th ss f prir wrk, it is lw uh t cus siifict ctti fr th wrkls w hv csir, w bliv tht ur rsults will hl if vilbl bwith lps tim s) AFS MFS Grp lps tim s) AFS MFS Writ Fiur : Cmpris f MFS AFS prfrmc MFS with schrus RPCs priritis is cmpr t vrsi f th Arw Fil Sstm Spups fr th tw wrkls f th GW tst r shw, rltiv t th prfrmc f AFS t KBs trffic r scl w furthr i prlll Th rphs i Fiur vlit th icrprti f RPC priritis, sic ll th frru wrkls imprv thir prfrmc substtill t lwr bwiths, rltiv t MFS with priritis Furthrmr, th crs i thruhput fr th

7 9 9 <;: < = = ) ) ) ) ) " " " " " " # # # # # # $ $ $ $ $ $,,, Grp i th GW wrkl v is lss th wul b pct with ruc bwith: hr uifrm priritis rsult i thruhput lir i th bwith, whil iffrtit priritis r lss ssitiv Th RC GC tsts shw th bfit f schrus writbck, sic th upts frm th cmpil wrkl r cmmitt sr t th srvr th with schrus writs, u t th vrlp f thik tim with schrus writs Fill, thuh uifrm priritis prvi bttr prfrmc fr th Writ cmpt f th RW tst t KBs s is t b pct, sic w r priritisi rs), this bfit lrl vishs t lwr bwiths Thuh w hv cctrt trmii th bfit f RPC priritis b cmpris f iffrt cfiurtis f MFS t thr, w hv ls prfrm fw primts t cmpr th prfrmc f MFS t str istribut fil sstm Fiur illustrts th rsult f rui th GW tst vr MFS Arw Fil Sstm AFS) stup; w us th Arl implmtti f th AFS cch mr ] th OpAFS srvr AFS uss UDP-bs RPC librr withut priritis Th rsults lrl crrsp t ths i Fiur MFS siifictl utprfrms AFS fr th frru Grp wrkl, sic AFS ffctivl uss schrus RPCs with uifrm priritis I th bckru Writ wrkl, AFS slihtl utprfrms MFS, but it is bth mr mtur sstm, mr ptimis th MFS fr this srt f cmmuicti Sic th rsults f rui th thr tsts r similr, w mit thm fr brvit NTFS wrkls I iti t msuri th prfrmc f MFS with sthtic wrkls, w hv ls cuct primts with trcs thr frm th Wiws NT fil sstm NTFS) ] Althuh MFS is implmt vrit f Ui, NTFS hs smwht iffrt itrfc t th fil sstm, th trcs wr cvrt t ru tp f MFS with littl ifficult Th riil trcs rcr fil ccsss st f mchis i LAN A mjrit f th ccsss wr lcl but sm wr t rmt mchis W trct subitrvls frm th trcs which ftur itrsti fil sstm bhviur prcss thm t rmv ccsss t fils vr MB i si This prprcssi ws cssr t limit th ifluc f trml lr NT sstm fils, which m up f th fil sstm trffic i sm prtis f th riil trcs Giv tht MFS rtrivs writs bck whl fils, iclui ths sstm fils wul hv istrt th primts t lw bwiths Tbl ivs sttistics fr th thr trcs: trc i which rs prmit, trc i which writs prmit, ctii cptill hv fil sstm trffic Ech trc ws ru vr MFS with th cmbitis f schrus schrus writs iffrtit uifrm priritis i prvius primts, th rsults r iv i Fiur T itrprt ths rphs, lk fr istc t th hv l br prmtr trc mstl rs mstl writs hv l urti s) pplictis uiu fils 9 ttl fil sis MB) r trffic MB) writ trffic MB) Tbl : NTFS trc prmtrs Ths trcs r rprsttiv pris f mi r writ ctivit Th urtis r frm th riil NTFS trcs Nt tht th ttl fil sis rprst th mut ftch b MFS uri th trc Whr this is c b th writ trffic, th itil trffic is u t w fils bi crt r isti s t tim s) tim s) Tim spt RPCs KBs) mstl rs mstl writs hv l str vrh priritis uifrm priritis uifrm schrus schrus Tim spt RPCs KBs) mstl rs mstl writs hv l str vrh priritis uifrm priritis uifrm schrus schrus Fiur : Grphs f NTFS trcs Ech trc r with schrus r schrus writs uifrm r iffrtit priritis Th ttl hiht f ch br ts th tim frm th first t lst writ, th sh prti ts th tim frm th first t lst r Th whit prtis t th tr tim ruir t cmplt ll writs ftr th lst r hs fiish

8 fr schrus writbck with priritis i th KBs rph This shws tht th ttl urti f th trc with this MFS cfiurti is 9 scs, but ll th ftch trffic is cmplt withi scs f th strt: this is siifict imprvmt vr th ltrtiv cfiurtis msur Th rmii 9 scs f th trc r tk up b schrusl writi bck fil upts I ll css th trcs tk siifictl lr th th riill i i NTFS, whr th wr mstl ccssi th lcl fil sstm thrfr h bwith cstrits Th rsults lrl rpt ths s i th micrbchmrks, t th tt tht th rtst prfrmc imprvmts r s t lw bwith wh thr is hih r-writ ctti, such s i th mstl-writs trc whr thr is 9 crs i th tim spt t r ll th fils Hwvr, v t th hihr bwith f KBs, thr is crs f Th mstlrs trc is t much ffct b chs i th cfiurti, lthuh thr is sliht crs i bth r writ tims fr priritis schrus writbck Uusull, t KBs th hv-l trc prfrms bst with uifrm schrus writbck: w c i ttribut this t ifficic i th RPC prtcl, sic ur trml hv l hih bwith it prfrms bttr wh ll msss hv th sm pririt Prftchi Prftchi is cmml us t imprv th prfrmc f lcl fil sstms, s wll s istribut fil sstms Hwvr, i fil sstm with whl-fil ccss, mchism is ruir t trmi pprprit i hits Erlir wrk i fil sstm i hs us clustri t riv fil rups frm cch ccss sttistics ], prict futur fil ccsss frm rct ccsss ], r llw pplictis t spcif i hits plicitl, 9] Itr-fil pcis c ls b us s surc f hits Fr istc, it m b kw tht crti shr librr is ruir t ru tt itr: i this cs it wul b vtus t rtriv th shr librr frm th srvr s wll s rtrivi th tt itr cutbl Altrtivl, plicit ifrmti such s th prti sstm s tbs f istll sftwr pcks, r thr pplicti-spcifi pc ifrmti c b us A f ths tchius cul b us t riv hits fr us b th MFS i subsstm; ur vluti uss hspcifi pc ifrmti, which is iccurt i sm css Rthr th rimplmti isti hit-rti mchism, w fcus th prfrmc f MFS with i, usi librtl simpl hit mchism fr th purpss f vluti Dpcis btw fils r cv usi fil rup, which is list f fil itifirs fr th rlt fils It is ssum tht ftr fil i th rup hs b ccss, it bcms vtus t th rmir f th fils i th rup A fil rup is implmt s spcil tp f fil withi th MFS fil sstm, with its w fil itifir, but t ttch t spcific irctr Th fil rup fil bls t, if, is f its ttributs Th MFS i subsstm rivs much f its ffctivss frm bi cmbi with priritis RPCs Whil th i lrithm i MFS is strihtfrwr, it c still mk b cisis withut lr vrll prfrmc plt bcus th itrfrc f i with thr fil sstm ctivit is miimis I th sm w tht sm lcl fil sstms cut spcultiv prtis t imprv prfrmc ], MFS mks us f th spcultiv cmmuicti f priritis RPCs i th hp f chivi bfit thruh i fils MFS i implmtti Th MFS cch mr icrprts smll i mul, which c b ptill bl t strt-up Wh it is iitilis, i thr strts iitits rusts i prlll with th mi ctivit f th cch mr Th cr cmpt f th cch mr lrts th i mul vr tim pplicti rs r writs fil, b clli th fil ccss ruti This ruti chcks whthr th fil bls t fil rup if t, th ccss is ir If it is mmbr f fil rup, th rup is put t th h f th list Th thr priicll mis th rup t th h f th list If th rup fil fr th rup is t i th cch, it rtrivs it frm th srvr Th it scs th fils i th rup i rr util it fis th first which is t i th cch, r t vlit, issus rust r vliti rust fr it If ll th fils r vli r i th cch, th rup is mv t th f th list Oc th cmplts, th thr rchcks th h f th list t fi th t fil t : w rup m w b t th h f th list s rsult f furthr pplicti ccsss t fils Prftch rusts r similr t rulr ftch rusts fr fils, with th cpti tht th r issu t th lwst lvl f pririt: ll thr RPC trffic tks prcc vr RPC, s shw i Tbl Prftchs r schrus, l is m t tim This is mr mttr f implmtti cvic th si cisi: thr wrk hs shw th bfits iititi multipl ccurrt s frm iffrt srvrs 9] MFS s t currtl mk us f timuts fr s, s w hv t rlir, but it cul sil t t t b i ttmpt tht s t cmplt i timl mr Th mi cmplit i implmti th i subsstm lis i hli m ftch cmpulsr ftch t srvic cch miss) fr fil which is lr bi This cflict riss vr frutl, prticulrl wh pplicti prfrms fst lir sc f fils i fil rup A fficit implmtti f i ruirs tht th m

9 B rups B rr G rr R writ Multirp Pus Simulus m ftch Simultus writbck 9 Fiur : Rltiv spup f wrkls with i Ths rphs shw th spup i b i i fr r f bwith vlus, rltiv t th tim tk with bwith f KBs i Whr tst cmpriss tw sprt prcsss, l th spup fr th frru prcss is shw ftch wit fr th t cmplt, r tht th b brt Issui ftch RPC t th sm tim s is i prrss lssl wsts bwith, sic it rtrivs th sm fil frm th srvr twic Th sm cul b tru if w pt fr brti s, sic brt cul b vr cls t cmplti MFS thrfr mks th m ftch wit fr th, but ls riss th pririt f th RPC t tht f rulr ftch prti, t prvt pririt ivrsi This ruirs itil ris-pririt RPC t th srvr, which rsults i mr vrh th th cs whr m ftch ccurs withut ftch- cflict O th thr h, th ftch c frutl mk us f th t lr trsfrr s still rsults i fstr rsps t th pplicti As w hv pli, th implmtti f th i subsstm is t sphistict Whil it will rch uilibrium if th ttl si f th fil rups i th list is lss th th cch si, thr is mchism t prvt th i subsstm rui h f ctul fil ccsss victi usful fils frm th cch, r victi fils which it hs but hv t t b rfrc b th usr Tchius fr prvti this bhviur hv b iscuss lswhr 9] Prftchi vluti Hvi i t MFS, w vlut whthr such strihtfrwr lrithm c hv bfit fr sm rprsttiv wrkls I rr t chrctris th ffct f i i, w r st f iht micrbchmrks Th primtl stup ws th sm s i th pririt tsts, thuh this tim MFS ws cfiur t ru with schrus writbck, RPC with priritis, l i ws ithr bl r isbl Th tsts wr ru t r f bwith vlus, s i th prvius scti Ech micrbchmrk csists f r tw prcsss ccssi fils, with sm r ll f th fils frmi fil rups Th R-Writ tst is th sm s i Scti, with fil rup fr th R t Th Cmpil MFS tst hs si fil rups fr th mi irctris f th sstm Multirp ccsss MB f t i tt fils, frmi sil fil rup Pus ccsss MB f smll fils, wits fr scs, ccsss MB mr; ll th fils r i sil fil rup Simultus Dm-Ftch rus s tw prcss O prcss ccsss fils f KB ch, which frm fil rup Th thr s th sm, but withut fil rup Simultus Writbck cuts i th sm w, but th sc prcss writs th fils t th srvr ist f ri thm Th rmii tsts ivstit th vrh pi fr wksss i th i lrithm B Grups uss irctris, ch ctii -KB fils frmi its w fil rup; its first itrti, th wrkl ccsss th first fil i ch irctr, th sc, th thirt-thir, t prvk lr mut f uslss s G Orr B Orr ivstit th ffct f th rr list f fils i fil rup: G 9

10 Orr ccsss th fils i th rup i th sm rr s th list; B Orr ccsss thm i rvrs rr Alsis f i Th rphs i Fiur shw th rsults f th primts Whr tst such s Simultus Dm-Ftch icrprts mr th wrkl, l th lps tim fr th frru wrkl th ccssi fil rup) is iv I mst f th micrbchmrks, i i frm th fil rups spcifi hs substtil imprvmt th prfrmc f th wrkl, vri with hw mbl it is t i I rl, mr surplus bwith mr thik tim rsult i imprv prfrmc: this turll ms tht th rtst imprvmts frm i r vit t hihr bwiths si ut f iht micrbchmrks ru t lst fstr wh bwith is KBs) I ctrst, t lw bwith mst wrkls s bfit, sic ll th bwith is ict t hihr-pririt trffic Ol tw tsts prfrm wrs with i th withut Th R-writ tst prfrms slihtl wrs u t its lr hv twrk ctti Th B Grups tst, which plits pr i hits, csisttl ur-prfrms wh i is us This ffct is u t th uslss i RPCs fli th uti lik impsi mir ls ch m ftch: cumultivl ths slw w th vrll prfrmc A usul phm is tht th B Orr tst csisttl utprfrms G Orr, v thuh th lttr trirs s i th crrct rr Th plti is tht, b si, th G Orr tst suffrs frm th fst lir sc phm scrib i Scti ll s i this tst cflict with m ftchs) I ctrst, t th strt f th B Orr tst, th i subsstm is bl t sm fils ccss t th f th tst, withut cflicti with m ftch It c thrfr chiv rtr spup Summr f rsults Dspit th simplicit f th MFS i implmtti, w hv shw tht wrkls which r mbl t fil-lvl i c chiv spups f t hih bwith, s much s t bwiths s lw s KBs Prftchi crris smll prfrmc vrh, v wh prfrm t th lwst pririt, which c ruc its ffctivss fr fst lir sc wrkls It is pssibl t cstruct cmbiti f fil rups wrkl fr which i c siifictl r prfrmc Withi th cstrits imps b ur fil rup rprstti, th mi cclusi w rw frm th tst css hibiti plt is tht th implmtti cul b imprv t icrprt mchism t ihibit i Th currt i lrithm s t crrlt fil ccsss with th prcsss which mk thm, but if this wr, tw chs p RPC tp fp) f) fp) f) pfp) fp) sp) s) 9 9 Tbl : Numbr f RPCs b tp i bwith vribilit tst Th tris ur p t pris i th tst Fiur ivs th bbrvitis fr RPC tps r likl t b bficil Th first wul ruc th rssivss f i fr istc, stti bt thrshl) frm fil rup if it ppr tht prcss ws t usi th fils bs its prir ccsss This wul ruc th vrh i th B Grups cs Th sc wul plicitl tct fst lir sc b prcss, b cuti th istcs f m ftch cflict fr fil rup, th isbl i frm th rup Prftchi bwith vribilit S fr, ur primtl rsults hv mstrt th bfits f MFS ptti mchisms t vrius lvls f bwith vilbilit, but t wh th bwith is chi vr th urti f th tst T cclu this scti w will scrib mpl f MFS trffic ur th cuti f th Simultus Writbck tst scrib i Scti This tst ivlvs tw simultus wrkls: writs fils KB t th srvr th thr rs KB fils frm th srvr, but is slihtl mifi frm riil vrsi t us lr thik tim f scs wh ccssi ch fil imprvi th pttil fr RPCs t vrlp) W bl schrus writbck r th tst with th sthtic bwith trc shw i Fiur ), which chs th bwith c pr sc This hs thr sctis, brif pri wh th bwith is t KBs, rul crs t KBs vr th curs f t scs, th th mitc f th KBs rt util th f th tst Th tst ws cut c with i bl, c with i, th RPCs wr th ivi ccri t which pri f th trc th trmit i Fr ch RPC, fur utitis r clcult: th tim spt uu fr bth th RPC rust rpl, th tim tk fr ch t b rciv, frm th first t th lst pckt This irs th tim spt t th srvr srvici th RPC, th ru-trip tim btw th clit th srvr, but ths utitis r smll cmpr t th thr csts Ths vlus r up fr ch f th RPCs withi prticulr pri, th rsults r shw i th Fiurs b), c), ) Th rphs shw hw priritis ffct RPCs hw i chs MFS bhviur I ll thr tim pris, mr tim is spt RPCs t ftch fil ttributs with i bl th withut Sic th tim t rciv ftch-ttributs rust r rpl is liibl, th icrs tim is u t rtr uu-

11 vilbl Bwith trc tim s) ttl tims) RPC tims t hih bwith rust uu rust s rpl uu rpl s fp) f) fp) f) pfp) fp) sp) s) RPC tp ttl tims) )) )) )) )) )) RPC tims t itrmit bwith rust uu rust s rpl uu rpl s "" ## $$$ $$$ $$$ $$$ $$$ $$$ $$$ $$$ $$$,,,,,, fp) f) fp) f) pfp) fp) sp) s) RPC tp ttl tims) RRR SSS TTT TTT UUU UUU DDD DDD DDD DDD EEE EEE EEE EEE ::: FFF FFF FFF FFF ;; GG GG AA AA AA AA AA AA AA AA << == >>>??? BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC CCC PPP QQQ NNN NNN OO OO HHH III JJ JJ JJ JJ KK KK KK KK LLL MMM RPC tims t lw bwith rust uu rust s rpl uu rpl s fp) f) fp) f) pfp) fp) sp) s) RPC tp ) b) c) ) Fiur : RPC trffic with vri bwith Grphs b), c) ) shw th tim spt RPCs uri cuti f th Simultus Writbck tst frm Scti, with th bwith vri ccri t th curv i ) RPCs r lbll s fllws: f = ftch-ttributs, f = ftch-t, pf =, f = m ftch t ris pririt f RPC, s = str-t Th tim spt RPCs is shw with i bl, t b p), isbl, t b ) Nt tht RPC itrctis c vrlp s th utitis fr iffrt RPC tps r t itiv Fr sm RPC tps, th tim spt prticulr ctivitis is liibl i prprti t th vrll tim: fr istc, ftch-ttribut rusts r smll hv vr lw trsmissi tim rltiv t thir uui ls i ls; s w hv s rlir, hih trffic c cus ls i th ru-trip tim fr smll RPCs Cvrsl, str-t RPCs hv hihr uti uui l i th bsc f i: this is u t th mjrit f th cmpti RPCs bi hih pririt ftch-t RPCs With i, ths RPCs r mstl rplc b s, which prt t lwr pririt th str-t RPCs, util pit whr ccurrt m ftch RPC riss thir priritis t th ftch-t lvl A cmpris f ftch-t RPCs rvls th ffct f th bwith crs T bi with, th tst ru with i prfrms ftch-t RPC t t th first fil, which trirs i frm its fil rup Bcus f th lr l btw fil ccsss, s cmplt tirl withut vrlppi m ftchs Ovr th curs f th sc pri f tim, bwith bcms isufficit fr t cmplt uri th s l btw ccsss, rispririt RPCs r trir b th csut cch misss As th bwith crss, th uui ls icrs s prprti f th ttl tim spt s Cch csistc Stuis f istribut fil sstms hv lrl cclu tht fil shri is ifrut i rl-purps virmts, ] Hwvr, w hv itifi clss f cch csistc scris s bi f hih imprtc iutl srv b isti mbil fil sstms Supps tht cmpl iri si is miti srvr upt b tms f sirs rchitcts, lctricl ctrctrs, irs, s ) whil -sit suprvisrs wrk frm ths sis usi mbil vics Ths suprvisrs r frm th srvr m ls ch th si, fr mpl t rflct f th cticis cutr rslv l s cstructi prcs Wh such usrs hpp t b wrki th sm lmt f th si, it is clr tht stisfi rust frm stl t whthr i frm th cch, r srvr tht hs t t s l writbck) wul b visibl t th usr cstl Str cch csistc is crtil chivbl i istribut fil sstms ], but must b implmt with schrus RPCs, ruirs ithr rrs r writrs t icur l t sur tht l th ltst vrsi f fil is ccss I ctrst, s w hv t i Scti, si fil upts t srvr schrusl hs tw pttil bfits: th prcss mifi th fil t wit fr th writ t cmplt,, if th upt is l i th l fr sm itrvl bfr bi writt bck, it m b suprs b ltr upt, thrfr c b mitt tirl Hwvr, ths bfits cm t th cst f ruc cch csistc, sic th vrsi f th fil str t th srvr is icsistt uri th tim tht th upt rmis uu fr trsmissi Ev thuh schrus writs i MFS r t l t rt upts, burst f upts t suc f fils m fl th lik t th srvr icrs th l bfr upts twrs th f th burst r cmmitt A thr clit ccssi th fil will ccss th stl vrsi, rthr th which icrprts th pi upt W thrfr rfr t this s hi upt, th cch csistc prblm cus b schrus writs s th hi upt prblm Mbil fil sstms such s C ] rl ptimistic ccurrc ctrl t rslv th cflicts rt b hi upts A ltrtiv pprch is t us vrit f cllbcks t llw clit t rpl writs schrusl, but rti str cch csistc Fr mpl, th Ech fil sstm ] frcs W thk Lrr Flsr his tm t Autsk fr thir hlp i ursti th fil ccss pttrs tht ris i cllbrtiv wrk pplictis fr vr lr rchitcturl iri si firms ]

12 th mifi clit t flush its upts whvr thr clit ccsss th fil, Flui Rplicti 9] sprts ivliti fil frm trsmitti its upt W hv implmt similr schm i MFS, i which ccss t fil which hs ucmmitt upt t iffrt clit will frc th writbck Th MFS csistc lrithm iffrs i its icrprti f fil ccss ifrmti Rthr th frc th sm lvl f csistc fr ll fils, MFS iffrtits btw privt fils, which hv rctl l b ccss b sil clit, shr fils, which r ccss b multipl clits Efrci cch csistc btw clits cssril ruirs tht shr fils r kpt hihl csistt, but mifictis t privt fils c b writt bck t th srvr lss rssivl Th tchiu f usi fil ccss pttrs t just cch csistc prtcl hs b us i th Sprit istribut prti sstm ], thuh i Sprit chs i cchi plic wr m wh fil ws p simultusl t iffrt clits, whil MFS uss lr-trm ccss sttistics Th rmir f this scti scribs ur csistc lrithm i til, vluti f its ffctivss i ruci cch icsistcis Th csistc mitc lrithm Th MFS cch csistc lrithm is it t chiv hih r f csistc, subjct t th cstrits imps b fil smtics th sirbilit f miimisi vrh W hv pt fr cmprmis which rsults i smll vrh but mits th pssibilit f trsit icsistc Th lrithm ruirs ifrmti but clit ccsss i rr t ivi fils ccri thir sttus, ithr shr r ushr Sic th fil srvr lws ssums tht ushr fil hs ucmmitt writ wh it is ccss b itil clit, icrrct ifrmti but th sttus f fil l ffcts th fficic f th lrithm Dtcti f such misclssificti rsults i th fil bi mrk s shr Th sttus f fils c b spcifi b th usr r b pplictis, r c b ifrr b th fil srvr ccri t hw it is ccss T b ffctiv, utmtic ifrc shul icrprt huristic fr th shri sttus f w fils, mchism fr cvrti shr fils t b ushr if th cs t b ccss b mr th sil clit Th currt implmtti i MFS ssums tht vr w fil is ushr, mitrs clit ccsss t fil ccri t vrlppi sris f tim pris t sur tht fils which r rulrl ccss rmi shr Sic th MFS fil mitri cmpt prts lrr tim scl th th primts csir i this ppr, w mit its tils fr brvit Wh prcss mifis fil, upt is schul t b pp t th l, th prcss ctius cuti withut hvi t wit fr th srvr t b ctct Th writbck thr th chcks th sttus f th fil th upt mifis: if th fil is ushr, th upt is uu fr trsmissi t th rhst prmtr vlu rr l btw ccssi muls - s prtis pr mul - l btw prtis - ms writr l btw ccssi muls - s prtis pr mul - l btw prtis - ms si f trl fils - KB Tbl : Cfiurti prmtrs fr th cch csistc vluti Iiviul istcs r uifrmll istribut withi th list rs ulr str-t pririt If th fil is shr thr shr upt is bi st, th thr bis trsmitti th upt t th str-fst pririt If thr shr upt is bi writt bck, schrus frwr ivliti RPC is m t th srvr t th hihst pririt, th th upt is uu fr ltr hih-pririt trsmissi Effctivl, frwr ivliti is l m if th upt ct b trsmitt immitl: i prctic it c thrfr b mitt t hih bwith r wh trffic is lw Hwvr, si frwr ivliti RPC withut ruiri th mifi prcss t wit itrucs trsit icsistc Wh th srvr rcivs frwr ivliti fr shr fil, r bis rcivi upt fr fil, it rcrs th itit f th writr, mrks th fil s irt issus cllbcks t ll th clits cchi it If f ths clits ftchs th fil bfr th upt hs b cmmitt, th srvr ss hihpririt srvr pull RPCs t th clits with utsti upts, which cuss thm t ris th pririt f str-t RPCs t pit trsmissi A ftch RPC fr ushr fil which is lr cch b iffrt clit lws trirs srvr pull, sic th srvr hs w f kwi if th fil hs utsti upts Fill, sic upts t shr ushr fils r writt bck t th srvr t iffrt priritis, th riil rr f th suc f upts is lr tirl prsrv Th upts t shr fils frm subsuc f th riil upts, s th upts t ushr fils Hwvr, implicit pcis btw fil upts r prsrv, sic th cmbiti f frwr ivlitis cmpulsr srvr pull RPCs fr ushr fils prvts clit frm ccssi w vrsis f fils i ctrvti f thir upt rr Eprimtl stup At th strt f this scti w itifi lr-scl cllbrtiv iri si s mpl f scri which fturs hih r f r-writ shri At prst w hv vlut th MFS cch csistc lrithm usi sthtic trc, thuh w r hpi t bti rl t frm such virmt i th futur

13 #" $ ; ; ; = HGFED I B C C J J J J J J K K K K K K T T T T T T U U U U U U V V V V V V W W W W W W N N N N N N O O O O O O X X X X X X X Y Y Y Y Y Y Y P P P P Q Q Q Q S \ \ \ \ \ \ ] ] ] ] ] ] r r r r r r r s s s s s s s Ž Œ t t t t u u u u ~ ~ ~ ~ ~ ~ vr tim s) Avr str RPC urti MFSCC scuif sciff iff schrus vr tim s) Avr urti f rr ftch MFSCC scuif sciff iff schrus )) )) )) )) )) 9 :: :: :: << <<= >> B,, -- umbr f RPCs LL LL LL LL LL LL LL MM MM MM MM MM MM MM ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ `` `` `` `` `` `` `` `` `` hh ii jj kk ll mm bb bb bb bb bb bb bb bb bb bb cc cc cc cc cc cc cc cc cc cc Ivlitis srvr pulls MFSCC scuif sciff srvr pulls RR RRS ff ff ff ff ff ff ff ff ff ttl tim s) 9 pp pp pp pp pp pp pp pp ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ Tim spt ivlitis MFSCC scuif sciff vv vv ww ww ˆˆ ˆˆ ˆˆ ˆˆ ˆˆ ˆˆ ˆˆ ŠŠ ŠŠ ŠŠ ŠŠ ŠŠ ŠŠ ŠŠ ) b) c) ) Fiur : Grphs fr cch csistc trc Ths rphs shw vrius fturs f th prfrmc rsults; i th ls, sc ts schrus ivlitis; sc schrus ivlitis, ivlitis; iff ts iffrtit writbck priritis fr shr ushr fils, uif ts uifrm priritis MFSCC is th MFS cch csistc lrithm I rph c), th hiht f br cuts th umbr f ivlitis; th whit prti cuts th umbr f srvr-pull RPCs Our primtl stup csisti f thr hsts: srvr, rr clit, writr clit Th bwith frm th rr t th srvr ws fi t KBs, th bwith frm th writr t th srvr ws vri ccri t th primt Th writr ws cfiur i f sv iffrt ws: with schrus writs; r with schrus, schrus r ivlitis, iffrtit r uifrm priritis fr writi bck shr ushr fils Th MFS ccurrc ctrl lrithm MFSCC) crrsps t schrus ivlitis with iffrtit pririt fr shr fils Bth clits ccss shr rpsitr f fils str th fil srvr, which csists f muls Ech mul hs scriptr fil st f - mmbr fils Mul scriptr fils r but KB i si th mmbr fils tk up vr f KB Th ttl si f ll th fils i th cllcti is MB Th writr wrkl csists f th writr upti muls i rm rr A upt t mul csists f suc f prtis, f which r rs r writs t fil i th mul; th rmii csist f writs t ushr trl fils, which r ch crt with uiu m Thr is pus btw ch prti lr pus btw upts t muls Th rr wrkl is similr, but ccss t mul csists f sris f rs, trl fils r vr ccss Th cfiurti prmtrs us t rt th rr writr wrkl r list i Tbl Th writr wrkl hs mil urti f tw miuts, whil th rr wrkl is t t trmit t th sm tim s th writr wrkl ctull fiishs sic lw bwith cul t its rui tim b tw miuts) Alsis f th rsults Fiur shws rphs f sm slct rsults frm th primts I rl, whil schrus writs prvi str ccurrc ctrl, th rsult i th lwst rt f cmplt writs i ll th tsts, sic th writr h pssibilit f vrlppi thik tim with schrus writbck At ll bwith lvls th MFSCC lrithm utprfrm schrus writs b t lst, ws m th ptis with th hihst writ thruhput This is clr frm rph ), which shws th vr tim t cmplt str RPCs iitit b th writr clui ivlitis) Hr MFSCC utprfrms ll f th ltrtivs This is bcus f th ruc umbr f ivlitis it rts, ls sic, i ctrst t mst f th thr schms, it is bl t tk vt f bth iffrtit writbck, f srvr-pull RPCs t ris th pririt f its writs Grph b) shws th prfrmc frm th rr s prspctiv Whil th writr is bl t crs its tim spt prfrmi str RPCs, th rr s vr tim spt ftchs icrss shrpl wh th fil i usti must b pull frm th writr Nturll, this cst must b wih ist th bfit f substtill icrs writr thruhput Diffrtit writbck succs i ruci th tim th rr hs t wit wh ccssi shr fil Grphs c) ) shw sttistics fr ivlitis srvrpull RPCs fr ths writr cfiurtis which mk us f thm MFSCC siifictl rucs th umbr f ivlitis it must trsmit b putti ff ivliti fil util it is t th l, t th ffct f this plic th umbr f srvrpull RPCs is mir Th scuif plic, which iffrs frm MFSCC i mitti iffrtit writbck, mks mr ivlitis icurs mr srvr-pull RPCs, bcus its str RPCs must cmpt with th RPCs t writ bck trl fils This icrss th cmmit l fr ch fil th liklih f it bi ccss b th rr whil it is bi writt bck I cclusi, ths primts mstrt tht fr th trc w hv mi, th MFS lrithm f schrus ivlitis iffrtit writbck is bl t miti cch csistc btw th tw clits t llw th writr t writ bck chs t th str t fstr th is pssibl with th ltrtiv schms W it t furthr vlut th prfr-

14 mc f th lrithm t trmi its ffctivss ur thr wrkls, with mr clits Cclusi Th rwi us f mbil cmputrs wirlss twrks hs rtl icrs th scp fr pti t ccss t vri twrk chrctristics This ppr hs plr ppli th tchiu f mlss ptti t istribut fil sstm t imprv its prfrmc Th cch mr fr ur MFS fil sstm icrprts fturs tht r t prst i isti fil sstms fr mbil hsts: ptti t bwith vriti thruh th us f priritis cmmuicti, fficit cch csistc prtcl usi fil ccss ifrmti t imprv prfrmc W hv vlut th ffct f ths fturs prfrmc t vri bwith lvls ur bth sthtic rl wrkls, iclui wrkl multi cllbrtiv t ccss with hih r-writ ctti, fu tht whil th itil csts imps r mstl hi, th c hv bfits which r vr visibl Aitill, th -ml tur f ptti i MFS llws clits t pt uickl t vrit f bwith citis withut substtil chs i prti Our vluti hs iclu cmpriss f MFS t cch mr cfiurtis crrspi t prir wrk, cfirm tht thr r situtis i which MFS wul utprfrm AFS, C Littl Wrk Hwvr, ths rlir sstms wr si fr mbil virmt which is substtill iffrt frm tht vilbl t Esstill, MFS is bl t prvi imprv prfrmc i pris f hih twrk ctti b fvuri cch vliti RPCs t rtriv fils vr thr tps f trffic W hv t cmpr MFS with LBFS sic thir pprchs r rthl, LBFS-stl lrithms r t prst i th rlir sstms w hv cmpr ist W ticipt tht implmti LBFS fil chuks i MFS wul furthr imprv prfrmc its prfrmc I futur wrk, w pl t ivstit th prfrmc f mlss ptti MFS i wi-r mr wb-lik virmts, s wll s furthr vluti th prfrmc f th MFS cch csistc lrithm W ls it t us MFS t furthr mi th bfits chivbl frm th utmtic rti f cchi plicis fr fils Ackwlmts W wul lik t thk Rbbrt v Rss, Wrr Vls, Emi Gü Sirr Pul Frcis fr cmmts sustis rri MFS W ls thk Rim Brr, Iril Gupt, Kvi Wlsh fr hlpful iscussis crrctis t this ppr Rfrcs ] B Atki K P Birm Evluti f ptiv trsprt prtcl I Prcis f th Aul Jit Cfrc f th IEEE Cmputr Cmmuictis Scitis Ifcm ), S Frcisc, Clifri, Apr ] M G Bkr, J H Hrtm, M D Kupfr, K W Shirriff, J K Oustrhut Msurmts f istribut fil sstm I Prcis f th th ACM Smpsium Oprti Sstms Pricipls, ps 9, Pcific Grv, Clifri, Oct 99 ] F W Ch G A Gibs Autmtic IO hit rti thruh spcultiv cuti I Oprti Sstms Dsi Implmtti, ps, 999 ] L Flsr Prsl cmmuicti, Spt ] J Griffi R Applt Prfrmc msurmts f utmtic i I Prcis f th ISCA Itrtil Cfrc Prlll Distribut Cmputi Sstms, Spt 99 ] J H Hwr, M L Kr, S G Ms, D A Nichls, M Str, R N Sibthm, M J Wst Scl prfrmc i istribut fil sstm ACM Trsctis Cmputr Sstms, ):, Fb 9 ] L B Hust P Hm Prtill cct prti Cmputi Sstms, ): 9, 99 ] A D Jsph, J A Tubr, M F Kshk Mbil cmputi with th Rvr Tlkit IEEE Trsctis Cmputrs: Spcil issu Mbil Cmputi, ):, Mr 99 9] M Kim, L P C, B D Nbl Sft, visibilit, prfrmc i wi-r fil sstm I Prcis f th First USENIX Cfrc Fil Str Tchlis, Mtr, Clifri, J ] J J Kistlr M Str Discct prti i th C fil sstm ACM Trsctis Cmputr Sstms, ):, 99 ] G H Kui G J Ppk Autmt hri fr mbil cmputrs I Prcis f th Sitth ACM Smpsium Oprti Sstms Pricipls, ps, Sit Ml, Frc, Oct 99 ] T M, A Birrll, A His, C Jri, G Swrt A chrt istribut fil cch with irctr writ-bhi ACM Trsctis Cmputr Sstms, ):, 99

15 ] A Muthitchr, B Ch, D Mièrs A lwbwith twrk fil sstm I Prcis f th Svtth ACM Smpsium Oprti Sstms Pricipls, Lk Luis, Albrt, Oct ] M N Nls, B B Wlch, J K Oustrhut Cchi i th Sprit twrk fil sstm ACM Trsctis Cmputr Sstms, ):, Fb 9 ] T W P, R G Gu, J S Him, D Rtr, P Rihr, A Gl, G H Kui, G J Ppk Prspctivs ptimisticll rplict pr-t-pr fili Sftwr Prctic Epric, ):, Fb 99 ] R H Pttrs, G A Gibs, E Giti, D Stlsk, J lk Ifrm i cchi I Prcis f th Fiftth ACM Smpsium Oprti Sstms Pricipls, ps, Cppr Muti Rsrt, Clr, Dc 99 ] R Sbr, D Glbr, S Klim, D Wlsh, B L Dsi implmtti f th Su twrk fil sstm I Prcis f USENIX Summr Cfrc, 9 ] M Str Th vluti f C ACM Trsctis Cmputr Sstms, ):, M 9] D A Str Epliti th -trmiism schr f st itrtrs t ruc rrt fil IO ltc I Prcis f th Sitth ACM Smpsium Oprti Sstm Pricipls, ps, St Ml, Frc, Oct 99 ] W Vls Fil sstm us i Wiws NT I Prcis f th Svtth ACM Smpsium Oprti Sstms Pricipls, ps 9 9, Kiwh Isl, Suth Crli, Dc 999 ] A Wstrlu J Dilss Arl fr AFS clit I Prcis f th 99 USENIX Cfrc, Fri Trck, Nw Orls, Luisi, Ju 99 ] J Yi, L Alvisi, M Dhli, C Li Vlum lss fr csistc i lr-scl sstms IEEE Trsctis Kwl Dt Eiri, ):, Jul 999