VERITAS File System 3.5 (HP OnlineJFS/JFS 3.5) Administrator's Guide (August 2003)

Chapter 2
VxFS Performance: Creating, Mounting, and Tuning File Systems
Choosing mount Command Options
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tranflush
Specifying the tranflush option is recommended when VxFS is used as the default boot file system (/stand).
When tranflush is enabled, all metadata updates for that file system are both logged and flushed to disk. This
greatly reduces the possibility of data and metadata inconsistency that can exist on a dirty file system before
running a file system check (the fsck command).
Using the tranflush option for non-boot file systems is not required, because fsck can be run on such file
systems if they are not clean. Boot file systems require using tranflush to reduce data or metadata
inconsistencies when the bootloader code accesses this file system after a crash (the bootloader code must
access the boot file system to select the kernel to boot before fsck can be run). Because the tranflush option
impairs file system performance due to the flushing operations, use it only for the /stand file system.
The tranflush option automatically enables the blkclear and log options. It is advisable to specify the
mincache=dsync mount option with tranflush. Thetmplog, delaylog, and datainlog mount options do
not operate with tranflush. The tranflush option must be explicitly specified when remounting the file
system. The tranflush option does not operate on read-only file systems or cluster file systems.
Mounting a File System with Large Files
If a mount succeeds and nolargefiles is specified, the file system cannot contain or create any large files. If
a mount succeeds and largefiles is specified, the file system may contain and create large files.
The mount command fails if the specified largefiles|nolargefiles option does not match the on-disk flag.
The mount command defaults to match the current setting of the on-disk flag if specified without the
largefiles or nolargefiles option, so it’s best not to specify either option. After a file system is mounted, you can
use the fsadm utility to change the large files option.
Managing a File System with Large Files
You can determine the current status of the largefiles flag using the fsadm command:
# mkfs -F vxfs -m special_device
# fsadm -F vxfs mount_point | special_device
You can switch capabilities on a mounted file system using the fsadm command:
# fsadm -F vxfs -o [no]largefiles mount_point
You can also switch capabilities on an unmounted file system:
# fsadm -F vxfs -o [no]largefiles special_device
You cannot change a file system to nolargefiles if it holds large files.
See the mount_vxfs (1M), fsadm_vxfs (1M), and mkfs_vxfs (1M) manual pages.