OCFS2: The Oracle Clustered File System, Version 2

Overview

This paper will review the various components of the OCFS2 stack, with a focus on the file system and its clustering aspects. OCFS2 extends many local file system features to the cluster, some of the more interesting of which are posix unlink semantics, data consistency, shared readable mmap, etc. In order to support these features, OCFS2 logically separates cluster access into multiple layers. An overview of the low level DLM layer will be given. The higher level file system locking will be described in detail, including a walkthrough of inode locking and messaging for various operations.