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Sunday, March 24, 2013

Change mount point under VCS.

It's my B'day today!!! On this occasion I can’t miss an opportunity to write a blog entry as I think, being a tech savvy  guy I should write something which would be the nice gift from me to myself..

On this special day, today I would like to share a blog entry with you all. So let's start...

Past week I was requested to change mount point of /opt/vdf to /data along with applicable alteration in VCS configuration to make sure VCS functionality should work as expected as before for this volume & mount resource.

The mount point needs to be renamed to /data is as follows –

# df -kh /opt/vdf/
Filesystem size used avail capacity Mounted on
/dev/vx/dsk/vdfdg/opt_vdf_vol
            400G 165M 375G 1% /opt/vdf

Hence in order to do so, I’ll have to –

Unmount the /opt/vdf filesystem and re-mount it on /data as mount point. Before we do so, check if any data resides under filesystem and if any application active processes running within the filesystem which needs to be renamed. In case if any application is running and using the filesystem which needs renamed then at first place you need to stop the application and verify if no application process is hooked with the filesystem & If data resides on filesystem then simply create a temporary filesystem with temporary mountpoint and then copy over the data from original filesystem needs to be renamed. I trust this is simple one and any experienced SA can certainly do it.

Now in order to remount the filesystem with new mountpoint, first you need to modify your VCS configuration a bit so that you can un-mount the filesystem successfully.

Obliviously, the first basic thing to verify that VCS cluster configuration is currently read-only mode or write mode. To verify that you can use below command.

# haclus -display | grep -i 'readonly'
ReadOnly 1

Where,

0 = write mode
1 = read only mode

Well, currently VCS configuration is in Read-only mode so let’s make it write mode.

# haconf -makerw

# haclus -display | grep -i 'readonly'
ReadOnly 0

Good, now we have VCS configuration in write mode so we can make appropriate changes to the configuration and save them.

Now change the appropriate attributes in VCS configuration for filesystem/mount point resource that we are supposed to rename. This may vary, in my case I’m not changing the volume name and changing just a mountpoint name so I’m modifying only “MountPoint” attribute for resource “optvdf_mnt”

# hares -modify optvdf_mnt MountPoint "/data"

To verify.

# hares -display optvdf_mnt | grep -i MountPoint
optvdf_mnt ArgListValues adevdf01s MountPoint 1 /data BlockDevice 1 /dev/vx/dsk/vdfdg/opt_vdf_vol FSType 1 vxfs MountOpt 1 "" FsckOpt 1 -n SnapUmount 1 0 CkptUmount 1 1 SecondLevelMonitor 1 0 SecondLevelTimeout 1 30 OptCheck 1 0 CreateMntPt 1 0 MntPtPermission 1 "" MntPtOwner 1 "" MntPtGroup 1 "" AccessPermissionChk 1 0 RecursiveMnt 1 0 VxFSMountLock 1 1
optvdf_mnt ArgListValues adevdf02s MountPoint 1 /data BlockDevice 1 /dev/vx/dsk/vdfdg/opt_vdf_vol FSType 1 vxfs MountOpt 1 "" FsckOpt 1 -n SnapUmount 1 0 CkptUmount 1 1 SecondLevelMonitor 1 0 SecondLevelTimeout 1 30 OptCheck 1 0 CreateMntPt 1 0 MntPtPermission 1 "" MntPtOwner 1 "" MntPtGroup 1 "" AccessPermissionChk 1 0 RecursiveMnt 1 0 VxFSMountLock 1 1
optvdf_mnt MountPoint global /data

At this point we are good to un-mount the filesystem with mountpoint named /opt/vdf.

# umount /opt/vdf
UX:vxfs umount: ERROR: V-3-26388: file system /opt/vdf has been mount locked

Error!!! Whenever I get any error I feel very happy as every error teaches something new & especially new errors which I never came across!

The Solaris native OS command "umount" may through below error -

Well this error occurs if the mount point is locked by VCS. This is for cases where VCS service groups having DiskGroup resources configured with UnMountVolumes attribute set and the volumes are mounted outside of VCS control. The purpose of the VERITAS File System (VxFS) Mount Lock is to prevent accidental unmounting of a VxFS file system. The feature is enabled for the VCS Mount resource by default. This feature can be disabled by setting the Mount resource attribute VxFSMountLock to 0.

# hagrp -resources vdfapp_sg
vdfapp_dg
vdfappIP
optcdvdf_mnt
optvdf_mnt
optcdvdf_vol
optvdf_vol

# hares -display vdfapp_dg | grep -i UmountVolumes
vdfapp_dg ArgListValues adevdf01s DiskGroup 1 vdfdg StartVolumes 1 1 StopVolumes 1 1 MonitorOnly 1 0 MonitorReservation 1 0 tempUseFence 1 SCSI3 PanicSystemOnDGLoss 1 0 DiskGroupType 1 private UmountVolumes 1 0 vdfapp_dg ArgListValues adevdf02s DiskGroup 1 vdfdg StartVolumes 1 1 StopVolumes 1 1 MonitorOnly 1 0 MonitorReservation 1 0 tempUseFence 1 SCSI3 PanicSystemOnDGLoss 1 0 DiskGroupType 1 private UmountVolumes 1 0 vdfapp_dg UmountVolumes global 0

To get rid of this error use the VxFS umount command for Solaris to manually unmount the file system.

# /opt/VRTS/bin/umount -o mntunlock=VCS /opt/vdf

To mount filesystem/volume on new mountpoint use –

# mount -F vxfs -o mntlock=VCS /dev/vx/dsk/vdfdg/opt_vdf_vol /data

# df -kh /data
Filesystem size used avail capacity Mounted on
/dev/vx/dsk/vdfdg/opt_vdf_vol
              400G  165M  375G  1%   /data

Make sure to save and make cluster configuration read-only.

# haconf -dump -makero

That's it! Done, isn't this easy! :)

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