VERITAS File SystemÖ 3.5 (HP OnlineJFS/JFS3.5) AdministratorÆs Guide (December 2002)

Chapter 1
The VERITAS File System
Extended mount Options
11
Using the delaylog Option for Enhanced Performance
The default VxFS logging mode, mount -o delaylog, increases performance by delaying the logging of some
structural changes, but does not provide the equivalent data integrity as the previously described modes.
That is because 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. delaylog is the default mount option.
Using the qlog Option for Enhanced Performance
VxFS provides the mount -o qlog= option to activate QuickLog for a file system. QuickLog increases VxFS
performance by exporting the file system log to a separate physical volume. This eliminates the disk seek
time between the VxFS data and log areas on disk and increases the performance of synchronous log writes.
See for details.
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 the tmplog option 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
VxFS provides superior performance for synchronous write applications. The default mount datainlog
option greatly improves the performance of small synchronous writes.
The mount convosync=dsync option improves the performance of applications that require synchronous data
writes but not synchronous inode time updates.
CAUTION The use of the convosync=dsync option violates POSIX semantics.
Support for Large Files
VxFS can support files up to two terabytes in size. See “largefiles | nolargefiles” on page 23 for information on
how to create, mount, and manage file systems containing large files.
CAUTION Some applications and utilities may not work on large files.