HP-UX Reference (11i v2 03/08) - 1M System Administration Commands A-M (vol 3)

m
mount_vxfs(1M) mount_vxfs(1M)
datainlog|nodatainlog
Generally, VxFS does O_SYNC
or O_DSYNC writes by logging the data and the time change
to the inode (
datainlog). If the
nodatainlog option is used, the logging of synchro-
nous writes is disabled;
O_SYNC writes the data into the file and updates the inode syn-
chronously before returning to the user.
Note: The
datainlog option is available only with the HP OnLineJFS product.
ioerror=disable|nodisable|wdisable|mwdisable
Sets the policy for handling I/O errors on a mounted file system. Multiple error policies
were implemented in VxFS to handle evolving storage technologies for which a single
approach is no longer adequate.
I/O errors can occur while reading or writing file data, or while reading or writing meta-
data. The file system can respond to these I/O errors either by halting or by gradually
degrading.
ioerror 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 following matrix shows how the file system responds to the various errors depending on
the policy set:
file file metadata metadata
read write read write
----------------------------------------
disable | disable | disable | disable | disable |
----------------------------------------
nodisable | degrade | degrade | degrade | degrade |
----------------------------------------
wdisable | degrade | disable | degrade | disable |
----------------------------------------
mwdisable | degrade | degrade | degrade | disable |
----------------------------------------
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 struc-
tural 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 takes steps (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 perfor-
mance 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 meta-
data 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 the VERITAS File System Administrator’’s Guide for
information on what 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 pre-
vious VxFS error handling policy.
If
wdisable (write disable) or mwdisable (metadata-write disable) is selected, the file
system is disabled or degraded, as shown in the matrix, 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. disable is the
default ioerror mount option for cluster mounts.
Note: If there is serious damage to the file system, or there is structural corruption of file
system metadata, VxFS marks the file system for full
fsck regardless of which I/O error
Section 1M−−472 Hewlett-Packard Company − 4 − HP-UX 11i Version 2: August 2003