7.5 Shared Disk
- 헌규임
- 이진현
- JuneL (Unlicensed)
It is managed disk using Mantech Volume Lock(MVL) bundled in MCCS.
Within a cluster, the application may be store the data on shared disk when it is equipped. MVL attach the file system on shared disk to the only active server and lock to the standby server to prevent file system corruption. When managed as mentioned above, shared disk is defined as the drive letter.
A shared disk agent of the MCCS manages the lock/un-lock of the disk and monitors volume is read/writable state through communication with the MVL driver.
Table of Contents
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
net start vollock
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.
- While both nodes (assumed as node A and node B) are in the power off state, bring power online on node A first.
- Install MCCS on node A.
- Add driver S: to MVL though ‘vollock /a s:’ command.
- Lock driver S: through ‘vollock /l s:’ command.
- Check if the driver S: is accessible. The volume access should be denied
- Power online node B when it is checked driver S: is locked to node A
- Apply the same process on node B.
- 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'.
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.
Adding
Add the shared disk resource.
Before adding the shared disk resource, you must make sure that there exists an addable shared disk on the OS.
- When add a resource from a group name, select a group → right click → 'Add Resource'. Or select Edit(E) from the main menu bar → select 'Add Resource'. Or select 'Add Resource' icon from the tool bar.
Select 'SharedDisk' from Resource Type lists and click 'Next' button. When add a resource from the shared disk resource type name, this step will be skipped.
If you select a driver character to be used for the shared disk resource, it will recommend a name.
When you select a drive letter, all of driver letters of the node owns even without the volume of external shared storage is displayed. Please note that do not select the driver letter of none shared storage.
[Figure] Shared Disk Resource Drive Character Selected- As Additional Settings, check disk option is available.
To use this option, select Use and enter check disk argument. (Default is /F)
Click 'OK' button.
[Figure] Defining check disk option Click the 'Finish' button to add the basic shared disk resource.
You can immediately check the result in the management web console.
Deleting
Select resource type → right click → delete resource.
The deleted resource will immediately disappear from the management web console.
Status
The following table explains the status switching of the MCCS resource caused by a user's command and the status.
The command assumes that it is generated by a user.
Shared disk agent: Manages the shared disks registered in MCCS.
| Status | Agent command | Description | Note |
|---|---|---|---|
Online The volume is unlocked. You can write to it. | Offline | MVL is used to prevent user from writing/reading data to and from the disk. | |
| Monitoring | MVL and temporary text file are created to monitor if you can write to the volume. | ||
Offline The volume is locked. You can neither read or write from and to the volume. | Online | MVL is used to allow user to write/read data to and from the disk. | |
| Monitoring | MVL and temporary text file are created to monitor if you can write to the volume. | ||
Fault The volume is online. But there is a problem caused by external elements. You cannot write to it. | Online | MVL is used to allow user to write/read data to and from the disk. | |
| Offline | MVL is used to prevent user from writing/reading data to and from the disk. |
Attribute
Show the unique attribute of shared disk resource.
| Attribute | Description | Type | Default | Edit | Note |
Chkdsk | If the option is set to true, when the volume is mounted, according to the checkdisk options(ChkdskArg), disk is tested for errors. | BOOLEAN | false | O | |
ChkdskArg | When the checkdisk (Chkdsk) option is set to true, the check disk command option is activated. | STRING | /F | O | |
DriveLetter | Designate the drive characters for the volume. | STRING | O |
Attribute value of ArgList arguments are the values that are added resources and the value can be changed or viewed through 'Specified Attribute’ list on the detailed information panel.