Veritas™ File System 5.0.1 Programmer's Reference Guide

■ Creates
■ Links
■ Unlinks
■ Renaming
■ Data appended
■ Data overwritten
■ Data truncated
■ Extended attribute modifications
■ Holes punched
■ Miscellaneous file property updates
Note: The FCL is supported only on disk layout Version 6 and later.
The FCL stores changes in a sparse file, referred to as the FCL file, in the file system
namespace. The FCL file is always located in
/mount_point/lost+found/changelog. The FCL file behaves like a regular file,
however, some user-level operations are prohibited, such as writes. The standard
system calls open(2), lseek(2), read(2) and close(2) can access the data in the FCL
file. All other system calls such as mmap(2), unlink(2), and ioctl(2) are not allowed
on the FCL file.
Warning: For compatibility with future VxFS releases, the FCL file might be pulled
out of the namespace, and these standard system calls may no longer work.
Therefore, Symantec recommends that all new applications be developed using
the programmatic interface.
See “Application programming interface for File Change Log” on page 27.
Using the File Change Log file
VxFS tracks changes to the file system by appending the FCL file with information
pertaining to those changes.
This enables you to do the following:
■ Use the FCL to determine the sequence of operations that have been performed
on the file system in general or on a specific file after a particular point in
time.
File Change Log
About the File Change Log file
18