Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

number of times the log wraps around. However, increasing the intent log size
can lead to greater times required for a log replay if there is a system failure.
Note: Inappropriate sizing of the intent log can have a negative impact on system
performance.
See the mkfs_vxfs(1M) and the fsadm_vxfs(1M) manual pages.
Extended mount options
The VxFS file system provides the following enhancements to the mount command:
■ Enhanced data integrity modes
■ Enhanced performance mode
■ Temporary file system mode
■ Improved synchronous writes
■ Support for large file sizes
See “Mounting a VxFS file system” on page 35.
See the mount_vxfs(1M) manual page.
Enhanced data integrity modes
For most UNIX file systems, including VxFS, the default mode for writing to a file
is delayed, or buffered, meaning that the data to be written is copied to the file
system cache and later flushed to disk.
A delayed write provides much better performance than synchronously writing
the data to disk. However, in the event of a system failure, data written shortly
before the failure may be lost since it was not flushed to disk. In addition, if space
was allocated to the file as part of the write request, and the corresponding data
was not flushed to disk before the system failure occurred, uninitialized data can
appear in the file.
For the most common type of write, delayed extending writes (a delayed write
that increases the file size), VxFS avoids the problem of uninitialized data
appearing in the file by waiting until the data has been flushed to disk before
updating the new file size to disk. If a system failure occurs before the data has
been flushed to disk, the file size has not yet been updated to be uninitialized data,
thus no uninitialized data appears in the file. The unused blocks that were allocated
are reclaimed.
Introducing Veritas File System
Veritas File System features
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