G lock token appoints replacements for any special

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Unformatted text preview: of a par.cular size •  Requires updates to the alloca.on map CS480 Principles of Data Management Spring 2013 Allocation Manager •  One of the nodes in the cluster is responsible for all alloca.on regions •  Ini.alizes free space sta.s.cs by reading the alloca.on map –  When the file system is mounted –  Loosely up ­to ­date via periodic messages from each node •  Directs different nodes to different regions –  Must be synchronized between nodes CS480 Principles of Data Management Spring 2013 Metanode for File Metadata –  The file is no longer being accessed on the metanode and ages out of the cache on that node •  When a node first accesses a file it: CS480 Principles of Data Management CS480 Principles of Data Management –  Prevents lock conflicts between nodes Spring 2013 Other File System Metadata •  Global metadata –  File system configura.on data –  Space usage quotas –  Access control lists –  Extended aHributes •  Centralized management to coordinate or collect metadata updates from different nodes •  Quota management –  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) •  Token manager keeps track of all lock tokens including: –  Acquisi.on –  Relinquishing –  Upgrading or downgrading a token •  The token manager could become a boHleneck? •  Or the size of the token state might exceed the token manager’s memory capacity? 9 2/1/13 CS480 Principles of Data Management Spring 2013 Token Manager Scaling (2/3) –  Why? •  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! Spring 2013 Optimizing Token Protocol (1/3) •  Revoca.on of token •  GPFS’s token...
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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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