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Introduction

Xsan is a high-performance storage area network (SAN) file system for Mac OS X and Mac OS X Server. It enables users to share centralized disk storage with multiple computers over Fibre Channel. With the Xsan file system installed, up to 64 Xserve or Power Mac systems can read and write to the same storage volume at the same time. Xsan features include the following:

• High-performance, 64-bit file system for SAN file sharing over Fibre Channel

• File-level locking for protected concurrent read/write access to shared volumes for up to 64 computers

• Metadata controller failover and Fibre Channel multipathing for high-availability, redundant configurations

• Flexible volume management for data consolidation, dynamic scaling of storage pools, and volume mapping

• “Affinities” for automatically directing files to specified storage pools—for example, source files are automatically written to the RAID 0 pool and processed files are automatically written to the RAID 5 pool

• Bandwidth reservation settings to reserve requisite SAN bandwidth for highest-priority applications

• User quotas for storage resource allocation

• Integration with any LDAP directory for centralized management of user and group access privileges

• Easy remote administration using the Xsan Admin utility for setting up and monitoring the SAN

• Compatibility with ADIC’s StorNext file system for heterogeneous SAN environments

Contents:

Organization of This Document
See Also

Programmers developing applications that take advantage of Xsan features should use this API. Xsan is particularly suited for applications used by professionals that collaboratively process audio and video data, IT departments that rely on SANs to consolidate and manage growing storage resources, and scientists that use computing clusters to work on computationally intensive projects that include large data sets.

The Xsan API uses fcntl(2) to send requests to and receive results from a Mac OS X kernel that includes Xsan. The API provides macros for use with fcntl(2) that allow you to allocate extent space for a file and get the list of extent space that has already been allocated for a file, get and set a file’s affinity, enable and disable real-time I/O for a storage pool or file descriptor, get the real-time I/O parameters for a storage pool, get and set quota limitations for a user or group, and query the kernel for Xsan version information.

Organization of This Document

This book contains the following chapters:

• “Xsan Overview” describes the terminology and concepts used in Xsan.

• “Xsan Tasks” explains how to use the system calls to perform Xsan related tasks.

See Also

Refer to the following reference document for XSan:

• Xsan Reference

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