Lh rs p2p a scalable distributed data structure for p2p environment
This presentation is the property of its rightful owner.
Sponsored Links
1 / 38

LH* RS P2P : A Scalable Distributed Data Structure for P2P Environment PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on
  • Presentation posted in: General

CERIA Laboratory. LH* RS P2P : A Scalable Distributed Data Structure for P2P Environment. W. LITWIN. T. SCHWARZ. H.YAKOUBEN. Paris Dauphine University [email protected] Santa Clara University (USA) [email protected] Paris Dauphine University [email protected]

Download Presentation

LH* RS P2P : A Scalable Distributed Data Structure for P2P Environment

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Lh rs p2p a scalable distributed data structure for p2p environment

CERIA Laboratory

LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment

W. LITWIN

T. SCHWARZ

H.YAKOUBEN

Paris Dauphine University

[email protected]

Santa Clara University (USA)

[email protected]

Paris Dauphine University

[email protected]


Lh rs p2p a scalable distributed data structure for p2p environment

Plan

  • Objective

  • Overview: SDDS & P2P

  • LH*RSP2P

    • Architecture

    • Addressing

    • Properties

    • Churn Management

  • Conclusion

  • 2

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Objective

    Objective

    Very Large Scalable Files

    High availabilityto deal with churn

    At mostone forwarding message for key search or insert or scan

    (fastest known performance)

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    SDDS (1993)

    • A File of records identified by keys

    • SDDS client nodes face the applications and send queries to SDDS server nodes

    • No centralized addressing

    • Servers contain application or parity data

      • In buckets

    • Overflowing servers split on new servers

    • Servers do not notify clients about splits

    4

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    SDDS (1993)

    • Clients use images of the file state for addressing

      • Key based

      • Range queries

      • Scans

    • Images get adjusted towards the file state during queries by Image Adjustment Messages

      • Triggered by incorrect addressing by the client

    • IAMs reflect the file evolution by splits or, rarely, merges.

    • IAMs reflect also the location changes because of failures and recovery

    5

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Sdds typology

    SDDS Typology

    VBI-Tree

    CHORD...

    BATON

    Structured P2P Schemes

    LH*, DDH, EH*,

    LH*sa

    LH*s

    Alg. Sign…

    IH*…

    LH*m LH*g

    Data Structures

    SDDS(1993)

    Classics

    Tree

    Hash

    m-d Tree

    1-dimensional

    1-d Tree

    d-dimensional

    k-RP*, SD-Rtree, DRT*,

    RP*,

    High Availability

    k-Availability

    Security

    LH*rs

    6

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Growth through splits under inserts

    New Peer

    SDDS Expansion

    Peer

    Clients

    7

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Image Adjustment Messaging

    SDDS Client Image Evolution

    Clients

    8

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    SDDS 2007 Prototypes

    • Available at CERIA site

    • Announced at DbWorld

    • Managing LH* RS and RP* files

      • LH* implementaton based on LH*LH n scheme

        • J. Karlsson’s Thesis & EDBT paper

      • In distributed RAM

      • Under Windows

      • Over 1 gbs Ethernet

    • Various functions

      • Response time reaching 30 microsec

      • Up to 300 times faster than disk files

    9


    Lh rs p2p a scalable distributed data structure for p2p environment

    P2P (1995 ?)

    • Autonomous nodes store and search data

    • By flooding in early systems

      • Freenet, Napster, Gnutella…

    • Structured P2P reduce the flooding

      • Using decentralized data structures

        • Distributed Hash Table (DHT) especially

          • Few folks know the concept is due to B. Devine

            • FODO 93

      • Chord, P-tree, VBI, Baton…

    • Structured P2P schemes are specific SDDS schemes

    10


    Lh rs p2p

    LH*RSP2P Peer

    Server Part

    LH*RS

    Client

    LH*RS

    DB

    j

    Candidate Peer

    Client &

    Spare Storage

    Candidate Peer

    i’

    n’

    Client Part

    LH*P2P Peer

    LH*RSP2P

    • Architecture based on LH*RS

      • ACM –TODS, Oct. 05)

    LH*RSP2P Peer

    LH*RS

    Client

    LH*RS

    PB

    Pupils

    Pupil’s IP = Its key C

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2P Addressing

    • Global Addressing Rule

    • a  hi(C ) ; /* a is the address of peer destination of the key C*/

    • if a < n then a  hi+1(C ) ;/* (i, n) state of an SDDS file, they are only known to the file coordinator node

    hi (C ) = C mod 2i

    • Client Address Calculus

    • a’  hi’(C ) ; /* a’ is the address of peer destination of the key C*/

    • if a’ < n’ then a  hi’+1(C ) ;

    12

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2P File Expansion

    • File starts with i = 0 and n = 0 and a single data bucket 0

    • Every bucketkeeps the bucket levelj of hash function hi last used to split, j = 0 initially.

    • Overflowing bucket m alerts the coordinator

    • Coordinator notifies bucket n to split

      • Usually n ≠ m

    • It sends the address of the pupil ready for the new bucket n + 2i

    • It also sends the addresses of the buckets that have been created since bucket n lastsplit

    13


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2P File Expansion

    • Bucket n applies hi + 1

    • About half of keys migrates to new bucket n + 2i

      • About half of pupils migrate as well

    • Bucket n andthenew one set j = j + 1

    • Coordinator performs

      • n = n + 1 if n = 2i then i = i + 1 and n = 0

    • Resulting address space growth, starting from i = 0 and n = 0:

      • 0 1

      • 0 2, 1 3 ;

      • 0  4, 1 5, 2 6, 3 7

      • 0  8, 1 9, 2 10, 3 11, 412, 513…7 15

    14


    Lh rs p2p a scalable distributed data structure for p2p environment

    Peer & Pupil Image Adjustment After Peer Split

    i’ = j - 1 ; /* j value after the split

    n‘ = a + 1  /* ais the splitting bucket ; n = a + 1

    if n’ = 2i’ then i’ = j + 1 ;  n’ = 0 ;

    • The adjustment concerns

      • Splitting peer a

      • New peer a’ = a + 2i

      • Every pupil of a and of a’

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    j=1

    j=2

    j=2

    j=2

    j=2

    j=2

    j=2

    i’=1

    n’=0

    i’=1

    n’=1

    i’=2

    n’=0

    i’=1

    n’=1

    i’=2

    n’=0

    i’=1

    n’=1

    i’=1

    n’=1

    P2

    P0

    P1

    P0

    P1

    P2

    P3

    i=1

    n=1

    i=2

    n=0

    CP

    Coordinator Peer (CP)

    Before splitting

    After splitting

    Example

    i’= j =1;

    n’= m+1= 1+1;

    If n’=21thenn’=0; i’= i’+1

    and

    (i’, n’)= (2,0)

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Server Address Calculus

    a’  hj (C ) ;

    if a’= a then exit/* Bucket a is the correct one

    else send C to bucket a/* Forwarding to bucket a’

    exit;

    • Simpler and faster than for LH*

      • As only one forwarding is possible

    17

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Peer Image Adjustment by IAM

    • IAM comes from the correct bucket

    • Bucket a is the forwardingone

    • Bucket level j is that of the correct bucket

      • 0f the forwarding one as well

    i’ j - 1, n’ a + 1 ;

    if n’ >2i’then n’ 0 ; i’ i’ + 1 ;

    • Same algorithm as for the adjustment of the local client and of pupils after a split

    18

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    j=4

    j=4

    i’=3

    n’=2

    i’=3

    n’=2

    P9

    P1

    9

    Peer Image Adjustment by IAM

    Checking and forward the key using A2

    9

    IAM

    a = 1

    j = 4

    Pairs

    j=4

    j=3

    i’=3

    n’=1

    i’=2

    n’=1

    i =3

    n=2

    P0

    P4

    PC

    19

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    j=4

    j=4

    i’=3

    n’=2

    i’=3

    n’=2

    P1

    P9

    9

    Peer Image Adjustment by IAM

    9

    IAM

    a = 1

    j = 4

    Pairs

    j=4

    j=3

    i’=3

    n’=1

    i’= 3

    n’= 2

    i =3

    n=2

    P0

    P4

    PC

    20

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Peers

    j=3

    j=2

    j=3

    j=3

    j=3

    i’=2

    n’=3

    i’=2

    n’=1

    i’=1

    n’=1

    i’=2

    n’=2

    i’=2

    n’=3

    P0

    P2

    P5

    P6

    i’=2

    n’=1

    i=2

    n=2

    i’=0

    n’=0

    PC

    Candidate Peer

    Pupil

    LH*RSP2P

    TUTOR, Update Pupil

    • Example of the File Expansion

    Assign a Tutor for Candidate Peer:

    LH-hash of its IP Address

    i=2

    n=3

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Properties of LH*RSP2P :

    • The maximal number of forwarding messages for the key search is one.

    • The maximal number of rounds for the scan search can be two.

    • The worst case addressing performance of LH*RSP2P as defined by Property 1 is the fastest possible for any SDDS or a practical structured P2P addressing scheme.

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Proof Property 1

    • Case 1 : i’ = i andn’ < n

    • Peer a addresses peer a’, using its image (i’,n’) from last split

      • No IAM came since.

    j = i’+1

    j = i’

    a

    2i’

    0

    n

    a’

    n+2i’

    a+2i’

    No forwarding

    23

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    j = i’+1

    j = i’

    a

    2i’

    0

    n

    n+2i’

    a’

    a+2i’

    Proof Property 1

    • Case 1 : i’ = i and n’ < n

    • Peer a addresses peer a’, using its image (i’,n’) from last split

      • No IAM came since.

    Forwarding possible for any address a’ between (a, n)

    24

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    j = i’+2

    j = i’+1

    j = i’

    n

    a

    2i’

    0

    n+2i’+1

    2i’+1

    a’

    Proof Property 1

    • Case 2 : i = i’ + 1 and n < n’

    • Peer a addresses peer a’, using its image (i’,n’) from last split

      • No IAM came since.

    Forwarding possible for any address a’ beyond [n, a]

    25

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Proof Property 2

    • Peer a sends the scan to all buckets in its image

      • Including its image (i’, n’)

    • Receiving peer a’ can have bucket level j as in the image

      • j (a) = j’ (a)

      • No forwarding of the scan

    • Or, bucket a’ split

      • Once and only once

        • j (a) = j’ (a) + 1

      • See the figs for the key address calculus

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Proof Property 2

    • Peer a’ forwards the scan to its (only) child

      • No child can have a child

      • Peer a would first need to split again as well

    • Every peer gets thus the scan and only once

    • There at worst two rounds

    27

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    Proof Property 2

    • The only faster worst case performance is zero forwarding messages

    • Every split has to be notified then to every peer

    • It would be against the scalability goal of every SDDS & structured P2P scheme

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2PChurn Management

    Bucket reliability group with k paritybucketsprotect against up to k bucket failures per group

    Data Record

    Parity Record

    5

    4

    3

    2

    1

    0

    Tutoring records

    Rank

    Data Peer

    Parity Peer

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2PChurn Management

    Peer leaves with notice

    Say that’s OK

    j

    j

    j

    … …

    Coordinator Peer

    i’,n’

    i’,n’

    i’,n’

    i’,n’

    Pm

    P0

    Pl

    Candidate Peer

    Notification

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2PChurn Management

    Peer leaves without notice or fails

    LH*RS Bucket Recovery

    j

    j

    j

    Forward

    Coordinator Peer

    i’,n’

    i’,n’

    i’,n’

    i’,n’

    Pl-1

    Pm

    Pl

    Parity Peer

    Query

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2PChurn Management

    Peer leaves without notice or fails

    LH*RS Bucket Recovery

    j

    j

    j

    i’,n’

    Pl

    Coordinator Peer

    i’,n’

    i’,n’

    i’,n’

    Pl-1

    Pm

    Parity Peer

    Answer

    32

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    LH*RSP2PChurn Management

    j

    Sure Search : Protects against outdated server read (transient communication or peer failure)

    i’,n’

    j

    j

    j

    Pl

    Coordinator Peer

    i’,n’

    i’,n’

    i’,n’

    i’,n’

    Pl-1

    Pm

    Pl

    Parity Peer

    Answer

    Query

    33

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Conclusion

    Conclusion

    LH*RSP2P require at most one forward message when addressing error occur

    Is the fastest known SDDS and P2P key based addressing algorithm

    Protects efficiently against churn

    Allows to manage very large scalable files

    Should have numerous applications

    Google ??

    34

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Current future work

    Current & Future Work

    • Implementation of peer node architecture and of tutoring functions

      • Using existing LH*RS prototype

      • Created by Rim Moussa & shown at VLDB 2004

    • Performance Analysis

    • Variants

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    END

    Thank you for Your Attention

    Work partly funded by the IST eGov-Bus project

    36

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    References

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


    Lh rs p2p a scalable distributed data structure for p2p environment

    38

    LH*RSP2P: A Scalable Distributed Data Structure for P2P Environment


  • Login