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7.5 Shared Disk

7.5 Shared Disk

2015/01/16

Introduction to the MVL Driver

Mantech Volume Lock (MVL) is a kernel drive which provides the function of managing the shared disk for Windows OS.
MVL locks access to the shared disk resource. You cannot access the volume of shared disk before it unlocks access. Only a node allow to access to the shared disk resource.
MVL can be managed in volume unit and partition unit of Window but it is not recommended. But it is recommended to use volume unit management.
It supports both GPT disk and MBR disk, and for file system, it supports NTFS only.

 

MVL Installation and Removal

MVL can enable load / unload driver and activate without the need to reboot the system after installation. MVL is automatically installed in the last step of the installation of MCCS.
MVL driver can be installed/unistalled manually through the command of, 'install.bat /uninstall.bat' of the '%MCCS_HOME%\bin\DiskAgent' directory.
MVS is developed in a way of legacy filter driver of Wiindows.
Therefore, service start and stop can be done through net command of Windows.
Following is the way of service start and stop using command line interface.

Start

Start
net start vollock

Stop

Stop
net stop vollock

When removing MCCS, removal is done for both MCCS and also MVL. To remove it completely. Execute 'unistall.bat of the bin' %MCCS_HOME%\bin\DiskAgent.

※ Recommendations for installation and uninstallation
MVL is a legacy kernel filter driver. Thus, you must first run the install.bat / uninstall.bat file provided by MCCS and reboot the system.

Example of Shared Disk Configuration

Following steps are recommended to manage shared disk resource through MVL after installing MCCS.

Assume that a driver letter S: is a shared disk resource in a cluster. 

  1. While both nodes (assumed as node A and node B) are in the power off state, bring power online on node A first.

  2. Install MCCS on node A.

  3. Add driver S: to MVL though ‘vollock /a s:’ command.

  4. Lock driver S: through ‘vollock /l s:’ command.

  5. Check if the driver S: is accessible. The volume access should be denied

  6. Power online node B when it is checked driver S: is locked to node A

  7. Apply the same process on node B.

  8. If both nodes are locked, add a new disk resource. 

Maintain the shared disk state to allow one disk access from one node and keep them locked to prevent the damage of data.

MVL Command

Volume control on MVL can be done through Vollock.exe command in '%MCCS_HOME%\bin\DiskAgent'.

Format
vollock [/option] [Drive letter:]

 

Option

Description

L

Locks the disk which is added MVL lock target list.

U

Unlocks the disk which is added MVL lock target list.

A

By adding MVL lock target list of Window registry can remain the lock state even after reboot. In addition, it can lock/unlock by adding MVL driver.

D

Remove the drive letter from MVL lock target list of Window registry.

W

It shows the state of the specific disk.

M

It shows whether disk is in mount/unmount state.

V

Show MVL version

status

It shows the state of lock and adding state in table form.

clear

Unlock all the volumes.

delete

Delete specific disk.

 

'Status' shows the Device Name and Lock information and Registry information as shown below.

[Figure] Volume lock Information

Check list 

To check if MVL driver is installed, it can be done through checking the list of Vollock driver is listed up by using 'fltmc' command. 

[Figure] Volume lock Driver Information

vollock.sys is registered through <Legacy> format since it is a legacy kernel filter driver.