Creating a shared LUN

You can use SnapDrive to create FCP- or iSCSI-accessed LUNs that are shared between clustered Windows servers.

Before You Begin

• Verify that the FCP or iSCSI services have been started on the storage system.

Considerations

Keep the following consideration in mind when creating a LUN:

• LUNs should be created using SnapDrive.

Steps

1. Perform the following actions to launch the Create Disk wizard:
   1. Select the SnapDrive instance for which you want to create a disk.
   2. Select Disks.
   3. From the menu choices at the top of MMC, navigate to Action > Create Disk .

   The Create Disk Wizard is launched.

2. In the Create Disk Wizard, click Next.

   The Provide Storage System Name, LUN Path and Name panel is displayed.

3. In the Provide a Storage System Name, LUN Path and Name panel, perform the following actions:
   1. In the “Storage System Name” field, type the storage system name where the LUN will be created or select an existing storage system using the pull-down menu.
   2. In the “LUN Path” field, type the LUN path or select the path on the storage system you added in Step a.
   3. In the "LUN Name" field, enter a name for the LUN and click Next.

   The Select a LUN Type panel is displayed.

4. In the Select a LUN Type panel, select Shared, and then click Next.
5. In the “Information About the Microsoft Cluster Services System” panel, verify that you want the disk to be shared by the nodes listed, and then click Next.

   The Select LUN Properties panel is displayed.

6. In the Select LUN Properties panel, either select a drive letter from the list of available drive letters or enter a volume mount point for the LUN you are creating. When you create a volume mount point, enter the drive path that the mounted drive will use: for example, G:\mount_drive1\.
   Note: The root of the volume mount point must be owned by the node on which you are creating the new disk.
   Note: You can create cascading volume mount points (one mount point mounted on another mount point); however, in the case of a cascading mount point created on an MSCS shared disk, you might receive a system event warning indicating that disk dependencies might not be correctly set. This is not the case, however, as SnapDrive will create the dependencies and the mounted disks will function as expected.
7. While still in the Select LUN Properties panel, complete the following actions:
   1. Click Limit or Do not limit for the option labeled “Do you want to limit the maximum disk size to accommodate at least one snapshot?”

      If you select Limit, the disk size limits displayed are accurate only when they first appear on the Select LUN Properties panel. When this option is selected, the following actions might interfere with the creation of at least one Snapshot copy:

      • The option is changed to Do not limit and SnapDrive is used to create an additional LUN in the same storage system volume.
      • A LUN is created in the same storage system volume without using SnapDrive
      • Data objects other than LUNs are stored on this storage system volume.
   2. Select a LUN size. The size must fall within the minimum and maximum values displayed in the panel.
   3. Click Next.

   If the settings on the storage system volume or qtree on which you are creating the LUN do not allow SnapDrive to proceed with the create operation, the Important Properties of the Storage System Volume panel is displayed, as described in Step 8. Otherwise, Step 8 is skipped.

8. The Important Properties of the Storage System Volume panel displays the settings that will be used for the volume or qtree you specified in Step 4 of this procedure.

   SnapDrive requires the storage system volume containing LUNs to have the following properties:

   • create_ucode = on
   • convert_ucode = on
   • snapshot_schedule = off
   Note: SnapDrive cannot proceed to create a LUN unless these settings are configured as shown. Therefore, you must accept these settings.
9. Click Next.
10. In the Select Initiators panel, perform the following actions:
    1. Double-click the cluster group name to display the hosts that belong to the cluster.
    2. Click the name of a host to select it.

    The available initiators for that host are displayed in the Initiator List in the lower half of the pane.

11. In the Initiator List pane, select an initiator for the LUN you are creating.

    If you select an iSCSI initiator, and an iSCSI connection to the storage system on which you are creating the LUN does not exist, SnapDrive launches the Create iSCSI Session wizard, and you are prompted to select a target portal and initiator. Also, if your target requires authentication of hosts that connect to it, you can type that information here. After you click OK, the iSCSI connection from the Windows host to the storage system is established, even if you do not complete the Create Disk wizard.

    If you have MPIO installed and you are using FCP, you have the option to select several FCP initiators.

12. Repeat Step 10 and Step 11 for all hosts, and then click Next.
    Note: The Next button remains unavailable until initiators for all hosts of a cluster have been selected.

    The Select Initiator Group management panel is displayed.

13. In the Select Initiator Group management panel, specify whether you will use automatic or manual igroup management. If you select automatic igroup management, SnapDrive uses existing igroups or, when necessary, creates new igroups for the initiators you specified in Step 10 through Step 12. If you select manual igroup management, you manually choose existing igroups or create new ones as needed.

    If you specify...	Then...
    Automatic igroup management	Click Next. You are done with igroup management.
    Manual igroup management	Click Next, and then perform the following actions: In the Select igroups panel, select from the list the igroups to which you want the new LUN to belong. Repeat this action for each node in the cluster. Note: A LUN can be mapped to an initiator only once. OR Click Manage igroups and for each new igroup you want to create, type a name in the igroup Name text box, select initiators, click Create, and then click Finish to return to the Select igroups panel. Click Next. Note: The Next button will remain unavailable until the collection of selected igroups contains all the initiators you selected in Step 11.

14. In the Specify Microsoft Cluster Services Group panel, perform the following actions.
    1. From the Group drop-down list, select one of the cluster groups owned by this node to which the newly created LUN will belong.

       OR

       Select Create a New Cluster Group to create a new cluster group and then put the newly created LUN in that group.

       Note: When selecting a cluster group for your LUNs, choose the cluster group your application will use. If you are creating a volume mount point, the cluster group is already selected. This is because the cluster group owns your root volume physical disk cluster resources. It is recommended that you create new shared LUNs outside of the cluster group.
    2. Click Next.

    The Completing the Create Disk Wizard panel is displayed.

15. In the Completing the Create Disk Wizard panel, perform the following actions:
    1. Verify all the settings.

       If you need to change any settings, click Back to go back to the previous wizard panels.

    2. Click Finish.

       Disk creation might take several seconds to complete. SnapDrive displays disk creation status in the lower panel of the center MMC pane.