How to troubleshoot mount errors

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Abstract[edit]

This article explains how to determine the possible causes of some mount error message not related with the health of the file system.

When using the mount command to mount a file system, the following error message is return:

"/dev/<vgname>/<lvolname> is already mounted, /<mountpoint> is busy, allowable number of mount points exceeded"

Example:

Verify that the file system is not currently mounted.

# grep mnt /etc/fstab
/dev/vg00/lvol9 /mnt vxfs delaylog 0 2

Try to mount the file system.

# mount /mnt
vxfs mount: V-3-21264: /dev/vg00/lvol9 is already mounted, /mnt is busy,
               allowable number of mount points exceeded

This particular error message is misleading. It actually should be read something like:

vxfs mount: V-3-21264: /dev/vg00/lvol9 is already mounted or /mnt is busy or
               allowable number of mount points exceeded

Once you establish the possible cause, verify each of them:

a) Logical volume is already mounted.

# bdf | grep "/dev/vg00/lvol9"

or

# grep "/dev/vg00/lvol9" /etc/mnttab

b) Or the mountpoint is busy

# fuser /mnt
/mnt:     5624c
 
# ps -p 5624
   PID TTY       TIME COMMAND
  5624 pts/tb    0:00 sh

Determine which mount point is hanging the bdf output[edit]

This script will test every mount point on the system. If any of them is unaccessible, the command will "stuck" on the first mount point that fails.

for mnt in $(cat /etc/mnttab | awk '{print $2}')
do
   echo Testing $mnt
   bdf $mnt
done

Authors[edit]