White Paper- Windows Server High Availability with Microsoft MPIO

The DSMSupportedDeviceList key contains the hardware ID’s of all devices that are capable of being associated with the selected DSM.

To search for hardware ID’s registered with more than one DSM:

In order to determine which DSM’s a hardware ID are associated with, perform the following steps.

1. Using Regedit, open the following registry key:

HKLM\\System\\CurrentControlSet\\Control\\MPDEV\\MPIOSupportedDeviceList 2. The list of current hardware ID’s will be displayed such as the example from regedit.exe below:

3. Select one line from the Value Data filed, and Right-Click and choose copy.

Such as “Vendor 8Product 16”. 4. From the Edit menu in Regedit.exe, choose Find. 5. In the Find What box, right-click, and choose Paste.

6. Click the Find Next button. This will jump to the first DSM that this hardware ID is

associated with. Make a note of the registry path listed at the bottom of the Registry Editor window such as the path to the MSDSM entry listed below.

HKLM\\System\\CurrentControlSet\\Services\\msdsm\\Parameters

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In order to check for registration with other DSM’s, repeat step 6 until the Registry Editor finishes searching the registry:

7. In order to disassociate the hardware ID with a DSM to prevent it from being claimed by a particular DSM, remove the hardware ID from only the entry under the DSM’s entry in the Services registry hive leaving only the hardware ID’s that you wish to have claimed by the DSM.

A reboot is required after this step for the changes to take effect.

To add a hardware ID to be used with MPIO:

1. Open the MPIO control panel.

On the Mpio’d devices tab, click the Add button.

2. In the Add MPIO Support dialog box, paste in the hardware ID for the device to be

managed by MPIO and then click OK.

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For information on determining the hardware ID of a device to be used with MPIO, see Appendix C : Determining the hardware ID to be used with MPIO.

After the device is claimed by MPIO, the device originally shown in Device Manager will be hidden, and a pseudo-LUN device will be shown in device manager.

For example, the single path disk device listed in device manager which is named “emBoot sanFly SCSI Disk device” will become a hidden device, and will be replaced with a new device named “emBoot sanFly Multi-Path Disk Device”.

The exact name will depend on a number of items, such as the type of device and the DSM being used.

The original disk device is still viewable in Device Manager by choosing ―Show Hidden Devices‖ from the Action menu.

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Appendix C – Determining the Hardware ID to be used with MPIO

In order to add the hardware ID for a device to MPIO to allow the device to be managed by MPIO, it is first necessary to obtain the hardware ID from the device, and then format the hardware ID differently so that it can be recognized by MPIO.

To determine the hardware ID for a disk device to use with MPIO, perform the following steps:

Note: These steps assume that the device is already configured and presented to the system.

1. Click Start, type ―Devmgmt.msc‖ (without quotes), and press ENTER.

2. In Device manager, click the plus symbol next to Disk Drives to expand the category. 3. Right-Click the desired disk device, and choose properties. 4. Click the Details Tab.

5. In the Property drop down list, select Hardware ID. 6. A list such as the example below will be displayed:

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