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

The policies are the following:
■ disable
■ nodisable
■ wdisable
■ mwdisable
■ mdisable
The disable policy
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 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.
The nodisable policy
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
super-block. For metadata read errors, VxFS sets the VX_FULLFSCK flag in the
super-block. For metadata write errors, VxFS sets the VX_FULLFSCK and
VX_METAIOERR flags in the super-block and may mark associated metadata as bad
on disk. VxFS then prints the appropriate error messages to the console.
See “File system response to problems” on page 145.
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.
The wdisable and mwdisable policies
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
41VxFS performance: creating, mounting, and tuning file systems
Mounting a VxFS file system