VERITAS Software Corporation

VERITAS, t h e VERITAS logo , VxFS, VxVM, Fi rstWat ch and VERITAS Fi rstWat ch are regi s t e re d trademark s o f VERITAS Softwa re Corporat i o n. VxServerSuite and VxSmartSync are t rademarks of VERITAS Softwa re Corporation. Other product names mentioned herein may be trademarks and/or regi s t e re d trademarks of their respective companies. Overview The VERITAS storage management product line has been designed in response to the needs of commercial computing environments. These are the systems that are now supporting mission critical applications and playing a major role in corporate computing services. Typical environments include online transaction processing systems, networked database servers, and high performance file services. VERITAS specializes in systems storage management and high availability technology which encompasses a product line that offers high performance, availability, data integrity, and integrated, online administration. VERITAS provides three complementary products: VERITAS FirstWatch®, VERITAS Volume Manager™, and the VERITAS File System™. The VERITAS File System is a high availability, high performance, commercial grade file system providing features such as transaction based journaling, fast recovery, extent-based allocation, and online administrative operations such as backup, resizing, and defragmentation of the file system. This is the first part in a series of VERITAS White Papers that discuss computer file systems. This first paper provides a discussion of the basic components and mechanics involved in a computer file system. It is intended to be a general discussion on these components, and their interaction. In this paper we will use a general UNIX file system model for discussion and introduce the basic mechanics behind UNIX file system read and write processes. Where applicable we will discuss certain features of the VERITAS File System as they apply to file system mechanics. Note: The audience for this paper includes systems engineers, administrators and integrators who desire a breakdown and explanation of the general internals and mechanics of a computer file system. For further reading on this subject, consult other VERITAS White Papers, including the File System Performance and VERITAS File System Performance White Papers. These papers discuss general file system performance mechanics as well as the performance related internals, mechanics, benchmark test results and analysis, of the VERITAS File System.