Le metadata vs le system metadata 1 user data byte

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Unformatted text preview: inciples of Data Management Managing Parallelism and Consistency Spring 2013 CS480 Principles of Data Management Spring 2013 Lock •  A cluster file system allows scaling I/O throughput beyond what a single node can achieve: –  Reading and wri.ng requires parallel access to mul.ple nodes in the cluster –  File system consistency and POSIX seman.cs require synchronizing access to data and metadata •  Synchroniza.on mechanism for enforcing limits on access to a resource –  For many threads of execu.on –  To enforce a mutual exclusion concurrency policy •  GPFS guarantees single ­node equivalent POSIX seman.cs for the file system. –  If two processes on different nodes access the same file, a read on one node will see either all or none of the data wriHen by concurrent write opera.on on the other node. CS480 Principles of Data Management Spring 2013 Achieving Synchronization(1/2) •  Distributed Locking Spring 2013 Lock Granularity •  Smaller granularity –  More overhead due to more frequent lock requests •  Larger granularity –  May cause more frequent lock conflicts Spring 2013 Achieving Synchronization(1/2) •  Centralized Management –  Every file system opera.on acquires an appropriate read or write lock to synchronize conflic.ng opera.ons on other nodes before reading or upda.ng any file system data or metadata –  Allows greater parallelism than centralized management as long as different nodes operate on different pieces of data/metadata CS480 Principles of Data Management CS480 Principles of Data Management –  All conflic.ng opera.ons are forwarded to a designated node, which performs the requested read or update –  For frequently updated and accessed data •  When lock conflicts are fre...
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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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