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Cn Bng Ti Trong Mng P2P C Cu Trc(Load Balancing in Structured P2P Networks)
Phan Anh &
Nguyn nh Ngha
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01/10/2008 Phan Anh & Nguyn nh Ngha
Ni dung:
1. Mt s khi nim c bn.
2. Mt cn bng ti: Nhng nguyn nhn.3. Mt s gii php cn bng ti.
8/7/2019 Cn Bng Ti Trong Mng P2P C Cu Trc
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Mt s khi nim (1)
Load (Ti): ph thuc vo tng h thngP2P c th, c th l:
S bit yu cu lu tr d liu.
Bng thng mng.
Lng thi gian m CPU cn x l cng
vic
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01/10/2008 Phan Anh & Nguyn nh Ngha
Mt s khi nim (2)
Target: ti ln nht m mt node mongmun nhn c.
Mc ch ca cn bng ti: duy tr hthng trng thi trong Load ca mtnode l nh hn Target.
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01/10/2008 Phan Anh & Nguyn nh Ngha
Cc nh danh Node c thkhng cn bng. Do chn ID ngu nhin.
Mt cn bng ti (2)
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01/10/2008 Phan Anh & Nguyn nh Ngha
Cc nh danh Node c thkhng cn bng.
Cc nh danh d liu cth khng cn bng.
- node- data
Mt cn bng ti (3)
8/7/2019 Cn Bng Ti Trong Mng P2P C Cu Trc
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01/10/2008 Phan Anh & Nguyn nh Ngha
britney.mp3
- node- data
tallat-song1.mp3
tallat-song2.mp3
tallat-song3.mp3
tallat-song4.mp3
Mt cn bng ti (3)
Cc nh danh Node c thkhng cn bng.
Cc nh danh d liu cth khng cn bng.
Hot spots: Cc nodes phichu ti nhiu hn cc node
bnh thng khc (b truyvn nhiu hn cc nodebnh thng khc).
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01/10/2008 Phan Anh & Nguyn nh Ngha
- node- data
Cc nh danh Node c thkhng cn bng.
Cc nh danh d liu cth khng cn bng.
Hot spots: Cc nodes phichu ti nhiu hn cc node
bnh thng khc (b truyvn nhiu hn cc nodebnh thng khc).
Cc node ra vo mng mt
cch ty tin.
Mt cn bng ti (4)
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01/10/2008 Phan Anh & Nguyn nh Ngha
Ni dung
Mt s khi nim c bn.
Mt cn bng ti: Nhng nguyn nhn.
Mt s gii php cn bng ti: Phng php 1: Virtual servers (servero).
Phng php 2: Khng s dng virtual servers.
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01/10/2008 Phan Anh & Nguyn nh Ngha
Virtual Servers (VSs)
Mc tiu: S lng keys/nodecn c phn b ng u.
Nguyn tc: Mi Node vt lchn mt s lng ngu nhincc nh danh.
Mi nh danh c dnh chomt Virtual server(VS).
Mi node vt l bao gm mts lng nht nh cc VSs.
Nh vy, mi node Vt l schu trch nhim cho cc vng(regions) khng lin tip trnvng trn nh danh.
Physical Nodes Virtual Servers
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01/10/2008 Phan Anh & Nguyn nh Ngha
Cn bng ti vi Virtual Servers (VSs)
Nguyn tc thc hin cn bng ti:
Di chuyn cc VSs t cc node vt l nngti n cc node vt l nh ti.
Vn t ra:
Gim ti a vic mt cn bng ti.
Gim ti a lng ti phi di chuyn (VSs).
Ti thiu ha cc lin kt cn duy tr.
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VSs Mt s nh ngha
n s nodes trong h thng.
li ti ca ni ti mt thi im c th.
ci capacity ca ni v d: bandwidth, disk space.
i h s s dng (utilization) ca node ni.
Khi i > 1, node n b nng ti, ngc li node n c coi
l nh ti.
H s s dng ca h thng (systemutilization).
i
ii c
l!Q
!
nnodes
n
nnodesn
c
lQ
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VSs Cc m hnh cn bng ti tnh
One-to-one
Mi node nh ti L nh k thi gian lin h vimt node bt k H.
Nu Hl node nng ti, virtual servers cchuyn t Hsang L Htr thnh node nh tinhng cng khng lm node L tr thnh nng ti.
L H
nh k thi gian lin h
Node ngu nhinVSs c di chuyn
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One-to-many Mt th mc D c ngu nhin t ra lu thng
tin v ti ca nhng node nh ti.
Mi node nng ti Hly mt vi node nh ti tvic lin h vi D.
Mt s VSs ca Hsau c chuyn ti mt hocnhiu node nh ti ng k trong D.
L
LH
L H
D
Thng tinv ccnode nhti
Virtual servers
VSs Cc m hnh cn bng ti tnh
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Many-to-many Mi th mc Dduy tr thng tin v load ca mt tp
cc node nh ti v nng ti.
Mi th mc D chy mt thut ton quyt nhvic di chuyn cc VSs t cc node nng ti ncc node nh ti.
Qu trnh c thc hin qua 3 giai on:
Unload. Insert (chn).
VSs swap (hon i VSs).
VSs Cc m hnh cn bng ti tnh
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01/10/2008 Phan Anh & Nguyn nh Ngha
Unload
25
7 6 4
10 8 4 3
T=6, L=7
T=20, L=17
T=24, L=25
A
B
C
Pool
T=6, L=5
A
T=24, L=22
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Insert (chn)
5
7 6 4
10 8 4
2
3
A
B
C
T=24, L=22
T=20, L=17
T=6, L=5
T=20, L=20
T=24, L=24
Pool
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VSs M hnh lai (Hybrid scheme)
Kt hp: one-to-many v many-to-many
Mi node: nh k thi gian bo co loads v capacity ti th mc D. Nu th mc D gi vic di chuyn VSs th thc hin
iu ny.
Mi th mc Lu gi bo co ca cc nodes. nh k thi gian di chuyn cc VSs sao cho:
Ti di chuyn c ti thiu ha. Khng lm cho cc node khc tr nn nng ti.
Trng hp khn cp ti node n Nu node n tr nn nng ti, ngay lp tc yu cu th
mc di chuyn li VSs.
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Tham kho
1. Chord: A Scalable Peer-to-peer Lookup Protocol forInternetApplications. Ion Stoica, Robert Morris, David Liben-Nowell, David R.Karger, M. Frans Kaashoek, Frank Dabek, Hari Balakrishnan.
IEEE/ACM Transactions on Networking (TON), 11(1):1732, 2003.2. Heterogeneity and Load Balance in Distributed Hash Tables.
P. Brighten Godfrey and Ion Stoica. INFOCOM 2004 + slides.
3. Load Balancing in Dynamic Structured P2P Systems BrightenGodfrey, Karthik Lakshminarayanan, Sonesh Surana, Richard Karp,Ion Stoica. INFOCOM 2004.
4. Simple Efficient Load Balancing Algorithms for Peer-to-PeerSystems. David R. Karger, Matthias Ruhl. 16th Annual ACMSymposium on Parallelism in Algorithms and Architectures.