Cular node in the near future when the access pahern

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Unformatted text preview: ther node Client 1 –  Maintain cache consistency between nodes Client 2 •  A token allows a node to cache data it has read from disk •  The data (cached in the node with the token) cannot be modified elsewhere without revoking the token first CS480 Principles of Data Management Spring 2013 1. User Data: Parallel Access (2/2) •  Byte ­range locking –  Parallel applica.ons can write concurrently to different parts of the same file •  If the byte ­range lock is very small? –  Locking overhead would be unacceptable Client 3 CS480 Principles of Data Management GPFS Fine Grain Sharing Spring 2013 Negotiating byte-range token (1/4) •  Node A acquires a byte ­range token for a whole file (zero to infinity) –  If there is no other node to access the same file, all read and write opera.ons are processed locally without further interac.ons between the nodes •  Traffic rela.ng to managing this lock would be very high 6 2/1/13 CS480 Principles of Data Management Spring 2013 Negotiating byte-range token (2/4) •  Node (file system node) B begins wri.ng to the same file –  Revoke at least part of the byte ­range token held by node A –  Node A checks whether the file is s.ll in use. •  Case 1: If the file is closed? –  Node A gives up the whole token and node B will be able to acquire a whole token •  Case 2: If the node A is s.ll using the file? CS480 Principles of Data Management Spring 2013 Negotiating byte-range token (3/4) •  Example –  Node A is wri.ng sequen.ally at offset m and node B is wri.ng at offset n –  Node A will relinquish its token from n to infinity (if m < n) –  Node A will relinquish its token from 0 to m (if m > n) –  Both nodes...
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This note was uploaded on 02/11/2014 for the course CS 480 taught by Professor Staff during the Spring '08 term at Colorado State.

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