HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide

Chapter 1 33
The VxFS File System
Extended mount Options
files that are written during the system crash or shutdown can lose data.
Any changes to a file are flushed to disk when the file is closed.
Enhanced Performance Mode
The HFS file system is asynchronous in the sense that structural
changes to the file system are not immediately written to disk. File
systems are designed this way to provide better performance. However,
recent changes to the file system may be lost if a system failure occurs.
More specifically, attribute changes to files and recently created files may
disappear.
The default logging mode provided by VxFS (mount -o log) guarantees
that all structural changes to the file system are logged to disk before the
system call returns to the application. If a system failure occurs, fsck
replays any recent changes to preserve all metadata. Recent file data
may be lost unless a request was made to sync it to disk.
Using delaylog for Enhanced Performance
VxFS provides the mount -o delaylog option which increases
performance by delaying the logging of some structural changes.
However, recent changes may be lost during a system failure. This option
provides at least the same level of data accuracy that traditional UNIX
file systems provide for system failures, along with fast file system
recovery.
Temporary File System Modes
On most UNIX systems, temporary file system directories (such as /tmp
and /usr/tmp) often hold files that do not need to be retained when the
system reboots. The underlying file system does not need to maintain a
high degree of structural integrity for these temporary directories.
Using tmplog for Temporary File Systems
VxFS provides a mount -o tmplog option which allows the user to
achieve higher performance on temporary file systems by delaying the
logging of most operations.
Improved Synchronous Writes
HP OnLineJFS provides superior performance for synchronous write