The Design and Implementation of Elastic Quotas: A System for Flexible File System Management

Ozgur Can Leonard, Jason Nieh, Erez Zadok, Jeffrey Osborn, Ariye Shater, Charles Wright

Department of Computer Science, Columbia University Technical Report , CUCS-014-02, June 2002

Abstract

We introduce elastic quotas, a disk space management technique that makes disk space an elastic resource like CPU and memory. Elastic quotas allow all users to use unlimited amounts of available disk space while still providing system administrators the ability to control how the disk space is al- located among users. Elastic quotas maintain existing persis- tent file semantics while supporting user-controlled policies for removing files when the file system becomes too full. We have implemented an elastic quota system in Solaris and mea- sured its performance. The system is simple to implement, requires no kernel modifications, and is compatible with ex- isting disk space management methods. Our results show that elastic quotas are an effective, low-overhead solution for flex- ible file system management.

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Columbia University Department of Computer Science