On ensures that only a few data blocks will be aected

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Unformatted text preview: manager monitors the growth of token state •  If necessary, revokes tokens to reduce the size of the token state •  Lock conflict and token revoca.on dominates the cost of token manager messages. •  Highest priority in managing token space is to avoid lock conflicts CS480 Principles of Data Management •  Acquiring a token will never require more than 2 messages to the token manager Spring 2013 Optimizing Token Protocol (2/3) –  Allows acquiring mul.ple tokens in a single message from the token manager •  When a file is accessed for the first .me, mul8ple tokens are acquired with a single token manager request: –  The necessary inode token –  Metanode token –  Byte ­range token to read or write CS480 Principles of Data Management Optimizing Token Protocol (3/3) •  When a file is deleted on a node –  The node does not immediately relinquish the tokens –  The next file created by the same node can re ­use the old inode and will not need to acquire new tokens •  A workload where users on different nodes create and delete files under their home directories –  Generates liHle or no token traffic Spring 2013 •  Token prefetch and token request batching –  Revoking node sends revoke messages to all nodes that are holding the token –  Revoking node collects replies –  Revoking node forwards these as a single message to the token manager CS480 Principles of Data Management Spring 2013 Token Manager Scaling (3/3) •  Par..on the token space and distribute the token state among several nodes in the cluster •  This was not an efficient way to address the issue. CS480 Principles of Data Management CS480 Principles of Data Management Spring 2013 Fault Tolerance •  Node Failures –  One or more node(s) fails •  Communica.on Failures – ...
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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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