Acquision relinquishing upgrading or downgrading a

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Unformatted text preview: ages are forwarded to the machine holding lock of the regions and those nodes execute the updates –  When the file system is mounted –  Loosely up ­to ­date via periodic messages from each node •  Directs different nodes to different regions –  Prevents lock conflicts between nodes 3 2/4/13 CS480 Principles of Data Management Spring 2013 CS480 Principles of Data Management Spring 2013 Other File System Metadata •  Global metadata –  File system configura,on data –  Space usage quotas –  Access control lists –  Extended aFributes •  Centralized management to coordinate or collect metadata updates from different nodes •  Quota management Token Manager Scaling GPFS –  Hands out large increments of disk space to the individual nodes wri,ng a file –  Quota checking is done locally with only occasional interac,on with the quota manager CS480 Principles of Data Management Spring 2013 Token Manager Scaling (1/3) Spring 2013 Token Manager Scaling (2/3) •  Token manager keeps track of all lock tokens including: •  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. –  Acquisi,on –  Relinquishing –  Upgrading or downgrading a token –  Why? •  The token manager could become a boFleneck? •  Or the size of the token state might exceed the token manager’s memory capacity? CS480 Principles of Data Management CS480 Principles of Data Management Spring 2013 Token Manager Scaling (3/3) •  GPFS’s token 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 •  File size is unbounded. Therefore, token state is unbounded •  If the byte ­range token is distributed, the case where a single node acquires a token for a whole file would be very frequent –  Prohibi,vely expensive! CS480 Principles of Data Management Spring 2013 Optimizing Token Protocol (1/3) •  Revoca,on of token –  Rev...
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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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