VERITAS File System 4.1 Administrator's Guide

VxFS Performance: Creating, Mounting, and Tuning File Systems
Choosing mount Command Options
Chapter 2 47
ioerror
Sets the policy for handling I/O errors on a mounted file system. I/O errors can occur while
reading or writing file data, or while reading or writing metadata. The file system can respond
to these I/O errors either by halting or by gradually degrading. The ioerror option provides
four policies that determine how the file system responds to the various errors. All four
policies limit data corruption, either by stopping the file system or by marking a corrupted
inode as bad. The four policies are disable, nodisable, wdisable, and mwdisable
If disable is selected, VxFS disables the file system after detecting any I/O error. You must
then unmount the file system and correct the condition causing the I/O error. After the
problem is repaired, run fsck and mount the file system again. In most cases, replay fsck is
sufficient to repair the file system. A full fsck is required only in cases of structural damage
to the file system’s metadata. Select disable in environments where the underlying storage is
redundant, such as RAID-5 or mirrored disks.
If nodisable is selected, when VxFS detects an I/O error, it sets the appropriate error flags to
contain the error, but continues running. Note that the “degraded” condition indicates
possible data or metadata corruption, not the overall performance of the file system.
For file data read and write errors, VxFS sets the VX_DATAIOERR flag in the superblock. For
metadata read errors, VxFS sets the VX_FULLFSCK flag in the superblock. For metadata
write errors, VxFS sets the VX_FULLFSCK and VX_METAIOERR flags in the superblock
and may mark associated metadata as bad on disk. VxFS then prints the appropriate error
messages to the console(see Appendix B, “Kernel Messages,” on page 203" for information on
actions to take for specific errors)..
You should stop the file system as soon as possible and repair the condition causing the I/O
error. After the problem is repaired, run fsck and mount the file system again. Select
nodisable if you want to implement the policy that most closely resembles the error
handling policy of the previous VxFS release.
If wdisable (write disable) or mwdisable (metadata-write disable) is selected, the file system
is disabled or degraded, depending on the type of error encountered. Select wdisable or
mwdisable for environments where read errors are more likely to persist than write errors,
such as when using non-redundant storage. mwdisable is the default ioerror mount option for
local mounts. See the mount_vxfs (1M) manual page for more information.
largefiles | nolargefiles
VxFS supports files up to 2 gigabytes in size. The maximum file size that can be created is 2
terabytes.