Home > Veritas Storage Foundation™ File System Manual Pages

MOUNT_VXFS (1M)
Maintenance Commands

Table of contents

NAME

mount_vxfs - mount a VxFS file system

SYNOPSIS

mount [ -V vxfs ][ generic_options ][ -o specific_options ] 

{ special | mount_point }





mount [ -V vxfs ][ generic_options ][ -o specific_options ]




 special  mount_point








AVAILABILITY



VRTSvxfs





DESCRIPTION



The
mount
command notifies the system that
special,
a VxFS block special device,
is available to users from
mount_point,
which must exist before
mount
is invoked.
mount_point
becomes the name of the root of the newly mounted file system
special.


Multiple
-o
options can be specified only in a comma-separated list.


Only a privileged user can mount file systems.





NOTES



The
cio
option operates only on 
\AIX 
5.2 and later.


Mount attempts are not blocked on CFS-mounted file systems.
This can lead to unmountable file systems if one ends up with cross-mounted
primary and secondary nodes after reconfiguring or migrating the nodes.
This issue can be resolved by migrating one of the primary nodes.


Only a file system with disk layout Version 6 can be mounted.


An attempt to mount a file system on a 32-bit kernel-booted system will fail.


The
cio
option is not supported on cluster file systems.





OPTIONS









generic_options




Supported by the generic
mount
command.
See the
mount
manual page.




-V vxfs




Specifies the VxFS file system type.




-o 




Specifies the VxFS-specific options in a
comma-separated list.
The available options are:






blkclear




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.










cio




Specifies the file system to be mounted for concurrent readers
and writers.
I/O on files in this file system, behave as if they were 
opened with O_CIO specified in the 
open() 
system call.


Concurrent I/O is a licensed  feature of VxFS.
If
cio
is specified,
but the feature is not licensed,
mount prints an error message and terminates without mounting the
file system.


The
cio
option cannot be disabled through a remount.
To disable the
cio
option the file system must be unmounted
and mounted again without the
cio
option.


The
cio
and
qio
options are mutually exclusive.




ckpt=ckpt_name




Mounts the Storage Checkpoint of a VxFS file system.
ckpt_name
is the name of a file system
Storage Checkpoint previously created by the
fsckptadm
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 created and exist only while
the Storage Checkpoint is mounted.
A Storage Checkpoint pseudo device name has the following format:





device_path:ckpt_name









Storage Checkpoints are mounted read-only by default,
but you can mount or remount them as writable using the
rw
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.




convosync=direct|dsync|unbuffered|closesync|delay




Alters the caching behavior of the file system for
O_SYNC
and
O_DSYNC
I/O operations.


The direct value handles any reads or writes with the
O_SYNC
or
O_DSYNC
flags as if the 
VX_DIRECT
caching advisory is set.


The
dsync
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 unbuffered value handles any reads or writes with the
O_SYNC
or
O_DSYNC
flags as if the 
VX_UNBUFFERED
caching advisory is set.


The closesync value delays
O_SYNC
or 
O_DSYNC
writes so that they do not take effect immediately.


If the closesync,
dsync,
direct,
or unbuffered
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
fdatasync(2)
call is performed on the final close of the descriptor.


The
delay
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.




crw




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.
crw
must be specified with the
-o cluster
option.
Without specifying
crw,
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
crw
in conjunction with
rw
or
ro
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
ro,crw,
or
rw,crw
as shown in the first column,
the secondary read and write capabilities
can still be set independently.
For a cluster mount,
rw
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
-o remount
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
(rw),
the underlying disk group must have the
activation mode attribute set to
sharedwrite
(sw).


If a cluster file system is mounted
ro,crw,
and the disk group activation mode is 
sharedread
(sr),
that cluster file system can never
be a primary,
and
must
be mounted
seconly
(see the 
seconly
option below).
See the
VERITAS Storage Foundation Cluster File System Installation and Administration Guide
and the Volume Manager
vxdg
manual page
for more information on disk activation modes.




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 synchronous writes is disabled; 
O_SYNC
writes the data into the file and updates the inode synchronously
before returning to the user.  




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.
mwdisable
is the default
ioerror
mount option for local 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. 
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 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 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 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 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 previous 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.


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 policy is in effect.




largefiles | nolargefiles




These options do not turn largefiles capability on
and off
(use
mkfs
or
fsadm
to set and clear the 
largefiles flag),
but they do verify whether a file system
is largefiles capable.
If
nolargefiles
is specified and the mount succeeds, 
the file system does
not contain any files two gigabytes or larger, and
such files cannot be created.
If
largefiles
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 
mkfs
or
fsadm.


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.




log | delaylog | tmplog 




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
delaylog.


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
st_atime
(see the stat(2) manual page).


In
log
mode,
all system calls other than
write(2),
writev(2),
and pwrite(2)
are guaranteed to be persistent once the system call returns to the
application.


In
delaylog
mode,
the effects of most system calls other than
write(2),
writev(2),
and pwrite(2)
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
tmplog
mode,
the effects of system calls have persistence guarantees
that are similar to those in
delaylog
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
delaylog
and
log
mode,
the
rename(2)
system call flushes the source file to disk to guarantee the persistence
of the file data before renaming it.
In both modes,
the
rename
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
fsync(2)
and
fdatasync(2)
system calls are guaranteed to be persistent once the calls return.
The persistence guarantees for data or metadata modified by
write(2),
writev(2),
or pwrite(2)
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 convosync= mount option,
has been specified for the file descriptor.


The behavior of NFS servers on a VxFS file system is unaffected by the
log,
delaylog,
and tmplog
mount options.  In all cases,
VxFS complies with the persistency requirements of the NFS v2 and NFS v3
standard.




logiosize=size




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
logiosize
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
512,
1024,
2048,
4096,
or
8192.
The default value is the sector size of the device.
The
logiosize
option is supported only on local mounts.




mand




Honor mandatory locking.
Without this option,
only advisory locking is performed even if
mandatory locking was enabled on a specific file,
which is done by setting the set-group-id bit and clearing the group execute
bit in the file's mode.




mincache=direct|dsync|unbuffered|closesync|tmpcache




Alters the caching behavior of the file system.


The
direct
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
unbuffered
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.


The
dsync
value handles any writes without the
O_SYNC
flag,
or one of the
VX_DIRECT,
VX_DSYNC,
and
VX_UNBUFFERED
caching advisories,
as if the
VX_DSYNC
caching advisory was set.


For the
closesync,
dsync,
unbuffered,
and
direct
values,
when the final close of a file descriptor referencing a file is performed,
the equivalent of an
fdatasync(2)
call is performed.


The
tmpcache
value disables delayed extending writes,
trading off integrity for performance. 
If 
blkclear
is used in conjunction with
tmpcache, 
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.




noatime




Directs the file system to ignore file access time updates 
except when they coincide with updates to
ctime
or
mtime
(see the
stat
manual page.
By default,
the file system is mounted with access time 
(atime) recording.
You can use the  
noatime
option to 
reduce disk activity on file systems where access times are not important.




noauto




Allows the file system to be mounted explicitly.
That is,
the
-a
option will not cause the file system to be mounted.
This option is normally used for filesystems listed in
/etc/fstab
file,
which should not be mounted automatically at boot time.




nomtime 




The 
nomtime 
option is for distributed applications that read and write
to the same file simultaneously from one or more cluster nodes.
nomtime 
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
nomtime 
option operates only on cluster mounted file systems
(-o cluster
option). 
See the
VERITAS Storage Foundation Cluster File System Installation and Administration Guide
for more information on parallel I/O.




qio | noqio




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,
mount
enables Quick I/O on the file system.
If Quick I/O
is not available, 
mount
mounts the file system without Quick I/O.
If
qio
is specified,
but the feature is not licensed,
mount
prints an error
message and terminates without mounting the file system.
If 
noqio
is specified, 
mount
disables Quick I/O even if the license is installed.




quota | grpquota |usrquota




Enables disk quotas.
The quota options are valid only on file systems that are
mounted read/write
(rw).


If you specify the
quota
option,
both user and group quotas are enabled.
If you specify the
usrquota
option,
only user quotas are enabled.
If you specify the
grpquota
option,
only group quotas are enabled.


To turn on user quotas,
there must be a file named
quotas
owned by root in the file system root directory.
Group quotas require a file named
quotas.grp.
If the appropriate file does not exist,
one is created.
The quota files stores usage limits for each user,
or for each group for group quotas.


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
vxedquota(1M)
for details on how to create and modify usage limits in the quotas file.




remount 




Changes the mount options for a mounted file system.
In particular,
remount
changes the logging and
caching policies.
It also changes a file system from
read-only to read/write.


remount
cannot change a file system from read/write to read-only,
nor can it set the
snapof
or
snapsize
attributes.




rw | ro 




Read-write or read-only.
The default is
rw.




seconly 




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
seconly
option to succeed,
primary must already be mounted.
seconly
must be specified with the
-o cluster
option.
The
seconly 
option overrides any policy that was
set using the
fsclustadm
command (see the
fsclustadm(1M)
manual page).
This option can be set or reset using the
-o remount 
option.
A remount with
seconly 
fails if the file system node is already the
primary for the file system.


Note:
The generic
mount
command does not support remount.




snapof=filesystem






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.




snapsize=size




Used in conjunction with
snapof.
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.




suid | nosuid 




setuid
is honored or ignored on execution.
The default is
suid.

















EXAMPLES



To mount a Storage Checkpoint of a file system,
first mount the file system,
then mount the Storage Checkpoint:





# mount -V vxfs /dev/vx/dsk/fsvol /fsdir
# mount -V vxfs -ockpt=myckpt /dev/vx/dsk/fsvol:myckpt /ckptdir









To unmount a file system,
unmount the Storage Checkpoint first:





# umount /ckptdir
# umount /fsdir









To unmount a file system:





# umount /fsdir







To have Storage Checkpoints mounted automatically
when the system reboots,
you can list them in the
/etc/filesystems
file as in the following example output from the
mount
command:





/dev/vx/dsk/fsqalv00 /fsqamnt0 vxfs Sep 17 19:48 rw,delaylog,suid
/dev/vx/dsk/fsqalv01 /fsqamnt1 vxfs Sep 17 19:48 rw,delaylog,suid
/dev/vx/dsk/fsqalv02 /fsqamnt2 vxfs Sep 17 19:48 rw,delaylog,suid
/dev/vx/dsk/fsqalv01:clone1 /clone/fsqamnt1clone1 vxfs Sep 17 19:51 rw,log,suid,ckpt=clone1














FILES







/etc/filesystems




File system characteristics









SEE ALSO



fdatasync(2),
fsync,
mount,
setuid,
stat,
qiomkfile(1),
fsadm_vxfs(1M),
fsck_vxfs(1M),
fsckptadm(1M),
mkfs_vxfs(1M),
umount_vxfs(1M),
fs_vxfs(4),
vxfsio(7)


VERITAS File System Administrator's Guide,


VERITAS Storage Foundation Release Notes,


VERITAS Storage Foundation Cluster File System Installation and Administration Guide

Last updated: 01 April 2006

Copyright ©2009 Symantec Corporation

All rights reserved.