mount_vxfs(1M) mount_vxfs(1M)
NAME
mount_vxfs - mount a VxFS file system
SYNOPSIS
[ generic_options ] specific_options ]
{ special | mount_point }
[ generic_options ] specific_options ]
special mount_point
DESCRIPTION
attaches special, a removable file system, to directory, a directory on the file tree. (This directory is also known as the mount point).
directory, which must already exist, becomes the name of the root of the newly mounted file system. If you omit either special or direc-
tory, attempts to determine the missing value from an entry in can be invoked on any removable file system, except /. special and direc-
tory must be given as absolute path names.
notifies the system that special, a VxFS block special device, is available to users from mount_point, which must exist before is invoked.
mount_point becomes the name of the root of the newly mounted file system special.
Unlike some file system commands, you cannot specify multiple options to only the last option is used.
If you invoke with no arguments, it lists all the mounted file systems from the mounted file system table,
The command notifies the system that special, a VxFS block special device, is available to users from mount_point, which must exist before
is invoked. mount_point becomes the name of the root of the newly mounted file system special.
Multiple options can be specified in a comma-separated list.
Only a privileged user can mount file systems.
Use and only on cluster-mounted file systems and determine cluster write and failover capabilities respectively. provides improved concur-
rency for applications employing parallel I/O.
The policy behavior for cluster mounts is different from local mounts. See the option description for details.
Be careful when accessing shared volumes with other utilities, such as that can write data to disk. It is possible to destroy data being
accessed from other nodes.
The and options are not supported on cluster file systems.
OPTIONS
generic_options
Supported by the generic command. See mount(1M).
Specifies the VxFS file system type.
Specifies the VxFS-specific options in a comma-separated list.
The available options are:
Clears all data extents before allocating them to a file
(requires synchronous zeroing of certain newly allocated extents). This prevents uninitialized data from being present in a
file at the time of a system crash.
Mounts the Storage Checkpoint of a VxFS file system.
ckpt_name is the name of a file system Storage Checkpoint previously created by the command (see fsckptadm(1M)).
mount_point is the directory on which to mount the Storage Checkpoint. special is the Storage Checkpoint pseudo device.
Storage Checkpoints are mounted on pseudo devices that do not appear in the system name space. The pseudo devices are cre-
ated and exist only while the Storage Checkpoint is mounted. A Storage Checkpoint pseudo device name has the following for-
mat:
device_path:ckpt_name
Storage Checkpoints are mounted read-only by default, but you can mount or remount them as writable using the option. A
file system must be mounted before any of its Storage Checkpoints can be mounted. A file system can be unmounted only after
all of its Storage Checkpoints are unmounted.
To mount a Storage Checkpoint in shared mode on a cluster file system, you must also specify the option (see below).
Mounts a file system in shared mode.
special must be a shared volume in a Cluster Volume Manager (CVM) environment. Other nodes in the cluster can also mount
special in shared mode. A local mount cannot be remounted in shared mode and shared mount cannot be remounted in local
mode.
The first node to mount special is called the primary node. The primary node handles intent logging for the cluster. Other
nodes are called secondary nodes. A secondary writable node is not allowed if the primary node is mounted as read-only
Alters the caching behavior of the file system for
O_SYNC and O_DSYNC I/O operations.
The value handles any reads or writes with the O_SYNC or O_DSYNC flags as if the VX_DIRECT caching advisory is set.
The value handles any writes with the O_SYNC flag as if the VX_DSYNC caching advisory is set. It does not modify behavior
for writes with O_DSYNC set.
The value handles any reads or writes with the O_SYNC or O_DSYNC flags as if the VX_UNBUFFERED caching advisory is set.
The value delays O_SYNC or O_DSYNC writes so that they do not take effect immediately.
If the or value is set and a file is written to using a file descriptor with the O_SYNC or O_DSYNC flag set, the equivalent
of an call is performed on the final close of the descriptor.
The value delays O_SYNC or O_DSYNC writes so that they do not take effect immediately. With this option, VxFS changes
O_SYNC or O_DSYNC writes into delayed writes. No special action is performed when closing a file. This option effectively
cancels data integrity guarantees typically provided by opening a file with O_SYNC or O_DSYNC.
The cluster read-write option allows
asymmetric mounts; that is, you can mount a specified cluster file system in read-only or read-write mode independently of
the other shared file system nodes. must be specified with the option. Without specifying the default functionality of the
cluster mount is retained; the read-write capability of cluster secondaries are the same as the cluster primary. You can
use the in conjunction with or as shown in the following mount compatibility matrix:
Secondary
------- ----------------------------------
Primary ro rw ro,crw rw,crw
------- ----------------------------------
ro yes no no no
rw no yes yes yes
ro,crw no yes yes yes
rw,crw no yes yes yes
If the primary is mounted with or as shown in the first column, the secondary read and write capabilities can still be set
independently. For a cluster mount, on the primary enables cluster-wide read-write capability.
The read and write capabilities can be changed from its original setting to another using the option. The read and write
capabilities can be changed according to the following matrix:
------- ----------------------------------
From/To ro rw ro,crw rw,crw
------- ----------------------------------
ro no yes yes yes
rw no yes no yes
ro,crw no yes yes yes
rw,crw no yes no yes
If a cluster file system is mounted read-write the underlying disk group must have the activation mode attribute set to
If a cluster file system is mounted and the disk group activation mode is that cluster file system can never be a primary,
and must be mounted (see the option below). See the and vxdg(1M) for more information on disk activation modes.
Generally, VxFS does O_SYNC or O_DSYNC writes by
logging the data and the time change to the inode If the option is used, the logging of synchronous writes is disabled;
O_SYNC writes the data into the file and updates the inode synchronously before returning to the user.
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. is the default mount option for local mounts. is the default mount option for cluster mounts.
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. 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 is selected, VxFS disables the file system after detecting any I/O error. You must then unmount the file system and cor-
rect the condition causing the I/O error. After the problem is repaired, run and mount the file system again. In most
cases, replay is sufficient to repair the file system. A full is required only in cases of structural damage to the file
system's metadata. Select in environments where the underlying storage is redundant, such as RAID-5 or mirrored disks.
If 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 per-
formance 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 the 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 and mount the file system again.
Select if you want to implement the policy that most closely resembles the previous VxFS error handling policy.
If (write disable) or (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 or for environments where read errors are more likely to persist than
write errors, such as when using non-redundant storage.
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 regardless of which I/O error policy is in effect.
Behavior on cluster file systems is somewhat different. If the policy selected is the file system is disabled only on the
node where the I/O error occurs. The file system is still accessible from the other nodes. If the I/O error is on the CFS
primary, a new primary is elected from the remaining nodes and the original primary becomes a secondary.
is the recommended policy for cluster file systems. With any other policy, a metadata I/O error can mark the file system
for a full file system check. If the CFS primary subsequently fails, the other nodes in the cluster cannot take over the
primaryship, thereby disabling access to the file system from all nodes in the cluster. Note: If the CVM disk detach policy
(the way unusable disks in a shared disk group are detached) is the I/O error policy must be disable.
These options do not turn largefiles capability on
and off (use or to set and clear the largefiles flag), but they do verify whether a file system is largefiles capable. If
is specified and the mount succeeds, the file system does not contain any files two gigabytes or larger, and such files can-
not be created. If is specified and the mount succeeds, the file system can contain files two gigabytes or larger, and
large files can be created. For a mount to succeed, the option must match the largefiles flag as specified by or
Note: Be careful when enabling large file system capability. System administration utilities such as backup may experience
problems if they are not large file aware.
Controls the timing of flushing the VxFS intent log and other metadata
to disk, which affects when operations are guaranteed persistent after a system failure. The default is
In the following description, the term "effects of system calls" refers to changes to file system data and metadata caused
by the system call, excluding changes to (see stat(2)).
In mode, all system calls other than and are guaranteed to be persistent once the system call returns to the application.
In mode, the effects of most system calls other than and are guaranteed to be persistent approximately 3 seconds after the
system call returns to the application. Contrast this with the behavior of most other file systems in which most system
calls are not persistent until approximately 30 seconds or more after the call has returned.
In mode, the effects of system calls have persistence guarantees that are similar to those in mode. In addition, enhanced
flushing of delayed extending writes is disabled, which results in better performance but increases the chances of data
being lost or unitialized data appearing in a file that was being actively written at the time of a system failure. This
mode is only recommended for temporary file systems.
In and mode, the system call flushes the source file to disk to guarantee the persistence of the file data before renaming
it. In both modes, the is also guaranteed to be persistent when the system call returns. This benefits shell scripts and
programs that try to update a file atomically by writing the new file contents to a temporary file and then renaming it on
top of the target file.
In all cases, VxFS is fully POSIX compliant. The effects of the and system calls are guaranteed to be persistent once the
calls return. The persistence guarantees for data or metadata modified by or are not affected by the logging mount options.
The effects of these system calls are guaranteed to be persistent only if the O_SYNC, O_DSYNC, VX_DSYNC, or VX_DIRECT flag,
as modified by the mount option, has been specified for the file descriptor.
The behavior of NFS servers on a VxFS file system is unaffected by the and mount options. In all cases, VxFS complies with
the persistency requirements of the NFS v2 and NFS v3 standard.
The performance of some storage devices (specifically,
devices using the read-modify-write feature) improves if the writes are issued in one or more multiples of a particular
size. When a file system is mounted with the option, VxFS writes the intent log in at least size bytes, or a multiple of
size bytes, to obtain the maximum performance from such devices. The values for size can be 1024, 2048, or 4096. The
default value is the sector size of the device. The option is supported only on local mounts.
Alters the caching behavior of the file system.
The value handles any reads without the O_SYNC flag, or any writes without the O_SYNC flag, VX_DSYNC, VX_DIRECT, and
VX_UNBUFFERED caching advisories, as if the VX_DIRECT caching advisory was set.
The value handles any writes without the O_SYNC flag, or one of the VX_DIRECT, VX_DSYNC, and VX_UNBUFFERED caching advi-
sories, as if the VX_DSYNC caching advisory was set.
The value handles any reads without the O_SYNC flag, or any writes without the O_SYNC flag, VX_DSYNC, VX_DIRECT, and
VX_UNBUFFERED caching advisories, as if the VX_UNBUFFERED caching advisory was set.
For the and values, when the final close of a file descriptor referencing a file is performed, the equivalent of an call is
performed.
The value disables delayed extending writes, trading off integrity for performance. If is used in conjunction with newly
allocated extents are not zeroed. If the system crashes, uninitialized data may appear in files that were being written at
the time of a system crash.
See vxfsio(7) for an explanation of VX_DIRECT, VX_DSYNC, and VX_UNBUFFERED.
Directs the file system to ignore file access time updates
except when they coincide with updates to or (see stat(2)). By default, the file system is mounted with access time record-
ing. You can use the option to reduce disk activity on file systems where access times are not important.
Allows the file system to be mounted explicitly.
That is, the option will not cause the file system to be mounted. This option is normally used for filesystems listed in
which should not be mounted automatically at boot time.
The option is for distributed applications that read and write to the same file simultaneously from one or more cluster nodes.
delays updating the file modification time in the specified cluster file system. Updating file modification and change
times are not synchronized within the cluster, which eliminates serializing two updates and improves concurrency. Use this
option in high-performance computing (HPC) environments when an application does not require consistent, cluster-wide file
modification times. The option operates only on cluster mounted file systems See the for more information on parallel I/O.
Enables or disables the VERITAS Quick I/O for Databases
option for the given file system. Quick I/O is available as a licensed feature of VxFS. By default, enables Quick I/O on
the file system. If Quick I/O is not available, mounts the file system without Quick I/O. If is specified, but the feature
is not licensed, prints an error message and terminates without mounting the file system. If is specified, disables Quick
I/O even if the license is installed.
For cluster file systems, is also the default if a Quick I/O license is present.
Enables disk quotas.
The option is valid only on file systems that are mounted read/write
To turn on user quotas, there must be a file named owned by root in the file system root directory. If this file does not
exist, a file is created. The file stores usage limits for each user.
VxFS maintains quota information in a private area of the file system. If the file system is mounted with quotas enabled,
and the file system was previously mounted with quotas disabled and was modified, the quota information is rebuilt. This
may take awhile depending on the amount of information to rebuild. See edquota(1M) for details on how to create and modify
usage limits in the quotas file.
Changes the mount options for a mounted file system.
In particular, changes the logging and caching policies. It also changes a file system from read-only to read/write.
cannot change a file system from read/write to read-only, nor can it set the or attributes.
Read-write or read-only.
The default is
Mounts a shared file system as a secondary only.
A secondary-only file system cannot assume the primaryship for the specified shared file system. For a mount with the
option to succeed, primary must already be mounted. must be specified with the option. The option overrides any policy
that was set using the command (see fsclustadm(1M)). This option can be set or reset using the option. A remount with
fails if the file system node is already the primary for the file system.
Mounts the file system as a snapshot of
filesystem, where filesystem is either the directory on which a VxFS file system is mounted, or the block special file con-
taining a mounted VxFS file system.
On cluster file systems, snapshots can be created on any node in the cluster, and backup operations can be performed from
that node. The snapshot of a cluster file system is accessible only on the node where it is created; that is, the snapshot
file system itself cannot be cluster mounted. See the for details on creating snapshots on cluster file systems.
Note: The filesystem argument cannot refer to a multi-volume file system unless the file system contains only one volume.
The special argument cannot refer to a volume set.
Used in conjunction with
size is the size in sectors of the snapshot file system being mounted. This option is required only when the device driver
cannot determine the size of snapof_special, and defaults to the entire device if not specified.
is honored or ignored on execution.
The default is
When VxFS is the default boot file system
on HP-UX, there can be no intent log replay during the initial stages of the boot process. To ensure data and metadata con-
sistency during the boot process, the option flushes all metadata updates to disk before returning from a system call. The
option therefore enables VxFS to approximate the behavior of a file system with no intent logging functionality. The option
automatically enables the and options. It is advisable to specify the mount option with must be explicitly specified when
remounting the file system.
The and mount options do not operate with The tranflush option does not operate on read-only file systems or cluster file
systems.
EXAMPLES
To mount a Storage Checkpoint of a file system, first mount the file system, then mount the Storage Checkpoint:
mount -F vxfs /dev/vx/dsk/fsvol /fsdir
mount -F vxfs -ockpt=myckpt /dev/vx/dsk/fsvol:myckpt /ckptdir
To unmount a file system, unmount the Storage Checkpoint first:
umount /ckptdir
umount /fsdir
To mount a Storage Checkpoint of a cluster file system on a VERITAS Volume Manager volume:
mount -F vxfs -o cluster,ckpt=ckpt_name
/dev/vx/dsk/dg_name/volname:ckpt_name /ckpt_mount_point
To have Storage Checkpoints mounted automatically when the system reboots, you can list them in the file as in the following example:
/dev/vx/dsk/fsvol /fsdir vxfs defaults 0 2
/dev/vx/dsk/fsvol:myckpt /ckptdir vxfs ckpt=myckpt 0 0
FILES
Table of mounted file systems.
SEE ALSO
qiomkfile(1),
edquota(1M),
fsadm_vxfs(1M),
fsck_vxfs(1M),
fsckptadm(1M),
fsclustadm(1M),
mkfs_vxfs(1M),
mount(1M),
setmnt(1M),
vxdg(1M),
vxumount(1M),
fdatasync(2),
fsync(2),
setuid(2),
stat(2),
fstab(4),
fs_vxfs(4),
mnttab(4),
vxfsio(7),
mount_vxfs(1M)