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Checkpointing & Rollback RecoveryGVHD: TS. Tn HnhNhm: Nguyn Khi - L Anh TunGii thiuCc giao thc khi phc likhi phc h thng v tnh trng nht qun sau khi c s ckh nng chu li bng cch lu li tnh trng tin trnh trong lc khng c lixem ng dng h thng phn tn nh l tp cc tin trnh giao tip qua mngim kim tratnh trng c lu li ca tin trnhTi sao s khi phc li ca h thng phn tn li phc tp?thng ip gy ra s ph thuc ln nhau gia cc tin trnh khi hot ng khng c li

Gii thiu(tt)S truyn b khi phc lis ph thuc c th buc cc tin trnh khng b tht bi phi khi phc lihin tng ny gi l hiu ng dominoCc k thut trnh hiu ng dominoKhi phc li im kim tra c iu phicc tin trnh iu phi cc im kim tra hnh thnh tnh trng nht qun ton h thngKhi phc li im kim tra gy ra truyn thngbuc mi tin trnh xc nh im kim tra da trn thng tin nhn t ng dngKhi phc li da trn nhn kkt hp im kim tra vi vic ghi li cc s kin khng nh trcim kim tra cc bTnh trng nht qunTnh trng ton cc ca h thng phn tntp cc tnh trng ca tt c tin trnh tham gia, tnh trng ca cc knh truyn thngTnh trng ton cc nht quntnh trng trong lc x l khng c li ca cc tnh ton phn tnnu mt tin trnh tnh trng nhn c thng ip th tnh trng tin trnh gi phi l ang gi thng ipim kim tra ton cctp cc im kim tra cc b ca mi tin trnhim kim tra ton cc nht qunkhng thng ip no c gi bi 1 tin trnh sau khi ghi nhn im kim tra c nhn bi tin trnh khc trc khi n ghi nhn im kirm traV d tnh trng nht qun

Giao tip vi th gii bn ngoiH thng phn tn thng giao tip vi th gii bn nhn hoc gi d liu tnh tonTin tnh th gii bn ngoitit trnh t bit tng tc vi h thng qua truyn thng ipCch thc chunglu mi thng ip u vo trn b lu tr n nh trc khi cho php ng dng x l thng ipK hiu || th hin giao tip vi th gii bn ngoi gi kt qu tnh ton

Thng ipThng ip ang truyn: l thng ip c gi nhng cha c nhnThng ip b mt: l thng ip tin trnh gi xc nhn l gi trong khi tin trnh nhn xc nh l cha nhnThng ip tr: tin trnh nhn cha ghi li v n khng hot ng hoc tin hnh khi phc liThng ip v ch: tin trnh nhn ghi nhn nhn trong khi tin trnh gi ghi nhn l cha giThng ip trng: do vic ghi nht k v tin hnh gi li ca tin trnh

V d cc thng ip

Vn khi phc t li

Khng iu phiMi tin trnh ghi nhn im kim tra ringu im:gim thi gian thc thiNhc im:chu nh hng ca hiu ng dominokhi phc li lumi tin trnh lu nhiu im kim tra nn i hi thm thut tonkhng ph hp vi ng dng thng xut thng tin ra ngoiCc tin trnh phi ghi nhn s ph thuc vo vic ghi li im kim tra ca nhau

K thut theo du ph thuc trc tip

C iu phiChn ghi nhn im kim trasau khi mt tin trnh ghi nhn im kim tra cc b, trnh thng ip khng ch, tin trnh duy tr tnh trng kha cho n khi ton b vic ghi nhn im kim tra hon thnhnhc im: cc tnh ton ca tin trnh b kha trong sut qu trnh ghi nhn im kim traKhng Chn ghi nhn im kim tratin trnh khng cn ngng thc thi trong khi ghi nhn im kim travn c bn l ngn tin trnh khng nhn thng ip m iu c th lm cc im kim tra khng nht qun

S c iu phi

Gy ra truyn thngHai loi im kim trat ng v p bucnh km thng tin lin quan n giao thc trn mi thng ip ng dngTin trnh s dng thng tin quyt nh c ghi nhn im kim traGhi nhn im kim tra bt buc trc khi tin trnh c th x l ni dung ca thng ipKhng c thng ip iu phi c trao iC hai loi da trn m hnh v da trn ch mc

Da trn nht kS dng cc s kin nh trc v khng nh trcS kin khng nh trc c th l s nhn c thng ip t tin trnh khc S kin gi thng ip khng phi l s kin khng nh trcGi nh tt c cc s kin khng nh trc c th c xc nh v cc yu t quyt nh c th c ghi liMi tin trnh ghi li cc yu t ny trong lc hot ng bnh thngDa trn nht k(tt)

iu kin nht qun khng v ch(e) :Stable(e) Depend(e) Log(e)Ghi nht k bi quan

Ghi nht k lc quan

Ghi nht k tnh c

Thut toan Koo-Touegcoordinated checkpointingKy thut sao lu va phuc hi phi hp thc hin mt mu checkpointing nht quan, tranh hin tng domino va vn livedock trong qua trinh phuc hi.Ky thut bao gm 2 phn: thut toan checkpointing va thut toan recovery.2222Thut toan checkpointing:Cac gia inh: knh truyn theo c ch FIFO, cac giao thc theo kiu end-to-end, s khi tao tin trinh n, khng co tin trinh tht bai trong sut thi gian thc thi thut toan.Co 2 loai checkpointing: pernament va tentativePermanent checkpoint: la checkpoint cuc b, mt phn cua checkpoint toan cuc nht quan.Tentative checkpoint: la checkpoint tam thi, se tr thanh permanent checkpoint khi thut toan kt thuc thanh cng.23Thut toan Koo-Touegcoordinated checkpointing (tt)23Thut toan checkpointing:Co 2 giai oan:Tin trinh khi tao thc hin tentative checkpoint va yu cu tt ca cac tin trinh khac thc hin tentative checkpoint. Cac tin trinh khng th gi thng ip sau khi thc hin tentative checkpoint. Tt ca cac tin trinh se co mt quyt inh cui cung ging nhau, o la: thc hin hay bo qua.Tt ca cac tin trinh se nhn quyt inh cui cung t tin trinh khi tao va a ra hanh ng phu hp.S chinh xac:Hoc la tt ca hoc khng co tin trinh nao thc hin permanent checkpoint.Khng co tin trinh nao gi thng ip sau khi thc hin permanent checkpoint.S ti u: khng cn thit la tt ca cac tin trinh u phai thc hin checkpoint.24Thut toan Koo-Touegcoordinated checkpointing (tt)24Thut toan rollback recovery:Phuc hi trang thai cua h thng v trang thai nht quan sau khi co tin trinh tht bai vi cac gia inh sau: s khi tao n nht, thut toan checkpoint va rollback recovery khng thc hin ng thi.Co 2 giai oan:Tin trinh khi tao gi mt thng ip n tt ca cac tin trinh khac yu cu khi ng lai cac checkpoint trc o.Tin trinh khi tao gi quyt inh cui cung cho tt ca cac tin trinh, tt ca cac tin trinh o se a ra hanh ng phu hp sau khi nhn c quyt inh a gi.25Thut toan Koo-Touegcoordinated checkpointing (tt)25S chinh xac: phuc hi lai t mt trang thai nht quan.S ti u: co th la khng cn phai phuc hi lai tt ca nu tin trinh o khng co s thay i nao.Vi du: {x2, y2, z2}= {x2, y2, z1}.26Thut toan Koo-Touegcoordinated checkpointing (tt)

26Thut toan Juang-Venkatesan cho checkpointing va recovery bt ng bCac gia inh: knh truyn thng la tin cy, thng ip nhn c theo th t FIFO, b nh m la khng gii han, vic tri hoan s truyn lai thng ip la tuy y nhng co gii han.Tinh toan/ng dung u tin la event-driven: tin trinh P ang trang thai s, nhn thng ip m, x ly thng ip, chuyn sang trang thai s va gi i. Vi vy, b ba (s, m, msgs_sent) m ta trang thai cua tin trinh P. Trong o, s: la trang thai cua tin trinh trc khi xay ra s kin; m: la thng ip; msgs_sent: la tp hp cac thng ip c gi i.Co 2 loai log storage:Volatile log: truy xut nhanh nhng se bi mt nu tin trinh crash, c chuyn sang stable log theo inh ky.Stable log: ngc lai vi volatile log.272728Thut toan Juang-Venkatesan cho checkpointing va recovery bt ng b (tt)Checkpointing bt ng b:Sau khi thc thi mt event, b ba {s, m, msgs_sent} c ghi lai ma khng co s ng b vi cac tin trinh khac.Checkpoint cuc b bao gm tp hp cac b ba {s, m, msgs_sent} cua mt tin trinh, u tin c lu tr trong volatile log, sau o c chuyn sang stable log.Thut toan recovery:- Cac ky hiu: RCVDi j(CkPti): s lng thng ip nhn c cua Pi t Pj. SENTi j(CkPti): s lng thng ip gi cua Pi n Pj.- Y tng: + Tim mt b checkpoint nht quan. + Thut toan thc hin da trn s thng ip gi va nhn.

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29Thut toan Juang-Venkatesan cho checkpointing va recovery bt ng b (tt)29Vi du:Gia s tin trinh Y tht bai va ey2 la event checkpoint cui cung cua Y.Thut toan recovery se c khi tao ca 3 tin trinh X, Y va Z.Khi tao cac checkpoint (CkPt): CkPtX ex3; CkPtY ey2; CkPtZ ez2.X, Y va Z gi cac thng ip ROLLBACK sau:Y gi ROLLBACK(Y, 2) n X va ROLLBACK(Y, 1) n Z.X gi ROLLBACK(X, 2) n Y va ROLLBACK(X, 0) n Z.Z gi ROLLBACK(Z, 0) n X va ROLLBACK(Z, 1) n Y.

30Thut toan Juang-Venkatesan cho checkpointing va recovery bt ng b (tt)30Vi du (tt):RCVDX Y(CkPtX) = 3 > 2 (2 la gia tri nhn c t ROLLBACK(Y, 2)).Do o, X thit lp CkPtX tr v ex2. Luc nay, RCVDX Y(ex2) = 2 2: OK.RCVDZ Y(CkPtZ) = 2 > 1 (1 la gia tri nhn c t ROLLBACK(Y, 1)).Do o, Z thit lp CkPtZ tr v ez1. Luc nay, RCVDZ Y(ez1) = 1 1: OK.RCVDY X(CkPtY) = 1 < 2 (2 la gia tri nhn c t ROLLBACK(X, 2)): OK.RCVDY Z(CkPtY) = 1 1 (1 la gia tri nhn c t ROLLBACK(Z, 1)): OK.Kt lun: {ex2, ey2, ez1} la mt b checkpoint toan cuc nht quan.

31Thut toan Juang-Venkatesan cho checkpointing va recovery bt ng b (tt)31Thut toan Manivannan-SinghalNhn xet: co mt s checkpoint khng dung n.Tin ti kt ni checkpointing ngang hang va khng ngang hang:Thc hin checkpoint bt ng b.S dung checkpointing communication-induced loai tr cac checkpoint khng dung n.Mi checkpoint u da trn mt checkpoint nht quan, xac inh dong phuc hi d va nhanh nht.Y tng thut toan:Mi checkpoint cua tin trinh u co mt s th t duy nht, c tng ln theo inh ky.Khi mt tin trinh gi thng ip ra ngoai, s th t cua no cung c gi theo.Khi mt tin trinh nhn thng ip, nu s th t nhn c ln hn s th t cua no, no buc phai thc hin checkpoint, va bt ky checkpoint c ban nao vi s th t nho hn la c bo qua.

3232Thut toan checkpointing:

Ci,k: checkpoint s th t k cua tin trinh Pi.Cac checkpoint thoa man nhng tinh cht sau:Ci,m cua Pi la ng thi vi C*, m cua tt ca cac tin trinh khac.Vi du: C2,3 la ng thi vi C1,3 va C3,3.Cac checkpoint C*,m cua tt ca cac tin trinh tao thanh mt checkpoint toan cuc nht quan.Vi du: {C1,4, C2,4, C3,4} tao thanh checkpoint toan cuc nht quan.Checkpoint Ci,m cua Pi la ng thi vi checkpoint Cj, n (m n).Vi du: {C1,3, C2,2, C3,2} tao thanh checkpoint toan cuc nht quan.33Thut toan Manivannan-Singhal (tt)

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34Thut toan Manivannan-Singhal (tt)

For a forced checkpointFor a basic checkpoint34Manivannan-Singhal - Checkpointing

M1 buc P2 phai thc hin checkpoint vi sequence number 3 trc khi x ly M1 bi vi M1.sn > sn2.35Vi du:35

36Manivannan-Singhal Recoveryinci: s cua tin trinh Pi .rec_linei: vi tri cua checkpoint cn phuc hi.

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37Manivannan-Singhal Recovery (tt)37

38Vi du:Manivannan-Singhal Recovery (tt)Khi P3 bi li va phuc hi:inc3 = 1 (inc3 = inc3 +1); rec_line3 = sn3 = 5.Checkpoint cui cung la C3,5. P3 broadcast thng ip ROLLBACK(inc3, rec_line3) n cac tin trinh con lai.P2 rollback n C2,5.P1 khng co checkpoint vi sequence number 5. Vi vy, no thc hin mt checkpoint cuc b va gan sequence number = 5.38Xin chn thnh cm n3939