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Application program interface

Veritas File System Developer's Kit (SDK) provides developers with the information necessary to use the application programming interfaces (APIs) to modify and tune various features and components of the Veritas File System. See the Veritas File System Programmer's Reference Guide.

VxFS conforms to the System V Interface Definition (SVID) requirements and supports user access through the Network File System (NFS). Applications that require performance features not available with other file systems can take advantage of VxFS enhancements.

About expanded application facilities

VxFS provides some facilities frequently associated with commercial applications that make it possible to perform the following actions:

• Preallocate space for a file.
• Specify a fixed extent size for a file.
• Bypass the system buffer cache for file I/O.
• Specify the expected access pattern for a file.

Because these facilities are provided using VxFS-specific ioctl system calls, most existing UNIX system applications do not use them. The VxFS-specific cp, cpio, and mv utilities use the facilities to preserve extent attributes and allocate space more efficiently. The current attributes of a file can be listed using the getext or VxFS-specific ls command. The facilities can also improve performance for custom applications. For portability reasons, these applications must check which file system type they are using before using these interfaces.