Task 5: Create a LUN

Applies To: Windows Server 2008

After you complete tasks 1 through 4, you can use the Provision Storage Wizard to create a logical unit number (LUN) on a Fibre Channel or Internet SCSI (iSCSI) storage subsystem. With the wizard you can optionally assign the LUN to your server or another server or cluster, create a volume on the LUN, and format the volume.

If you create a LUN but do not use the wizard to create a volume on it immediately, you can use Disk Management to create the volume later. In this case the disk associated with that LUN will be visible to any server or cluster that you assign it to, but it will be offline. Before you can create a partition or volume on that disk, you must use DiskPart or Disk Management to bring the disk online. For more information about how to bring a disk online, see:

To create a LUN

  1. In the console tree, click LUN Management.

  2. In the Actions pane, click Create LUN.

  3. Follow the steps in the Provision Storage Wizard, providing the information described in Table 1.

The following table contains some general recommendations and information about each one of the pages in the Provision Storage Wizard:

Table 1   Completing the Provision Storage Wizard

Wizard Page Details

Before You Begin

Verify that storage is available on the subsystem and, if you want to use the wizard to assign the LUN to a server, the storage area network (SAN) server connections have been configured.

Storage Subsystem and Type

Select the subsystem on which to create the LUN.

The list of subsystems specifies the total capacity of each available subsystem, the type of subsystem (Fibre Channel or iSCSI), and the percentage of free space.

LUN Type

Specify the LUN type to create:

  • The list of LUN types includes each LUN type that is available on the selected subsystem and specifies the maximum-size LUN for each type.

  • Fault tolerant LUN types require more disk space than simple LUNs. Therefore, the maximum size of the LUN is smaller than for a simple LUN.

LUN Name and Size

Type a name for the new LUN and specify the size of the LUN:

  • The LUN name can have as many as 63 characters.

  • Depending on the version of the Virtual Disk Service (VDS) provider that the subsystem is running, you may not be able to type a name for the LUN.

  • Type the LUN size and click the drop-down list to select between megabytes (MB), gigabytes (GB) and terabytes (TB).

iSCSI Target (iSCSI only)

If iSCSI targets have already been created on the subsystem, you can assign the LUN to one of those targets now. You can also leave it unassigned for later use.

Server Assignment

Choose to assign the LUN to a server or cluster. You can also choose to leave it unassigned for later use.

Server Access (Fibre Channel only)

If you chose to assign the LUN and you have already configured your server connections, you can select the server or server cluster the LUN will be assigned to.

Volume Creation

If you chose to assign the LUN to the server you are currently managing with the Storage Manager for SANs snap-in, you can create an NTFS volume for the LUN.


If you select to format the volume:

  • As a general rule, leave the Allocation unit size option as Default. The allocation unit size is the smallest amount of disk space that can be allocated to hold a file. Windows selects default sizes based on the size of the volume. These default sizes are selected to reduce the amount of space that is lost and the amount of fragmentation on the volume.

  • The Quick Format option speeds the volume creation process on large LUNs. If you want to scan for bad sectors during the formatting process, clear the check box for this option and a full file format will be done.

If you prefer, you can select not to format the volume and can use Disk Management to format it later. For more information about Disk Management, see http://go.microsoft.com/fwlink/?LinkId=93544.

Review Settings and Create Storage

Before creating the LUN, the wizard lists all the properties that you have selected for the new LUN. Click Create to start the LUN creation process.

Monitoring the status of LUN creation

The process of creating a LUN can take minutes or hours, depending on the size of the LUN. Do not close Storage Manager for SANs while a LUN is being created. If the session ends before the process completes, you might not be able to determine the completion status for the LUN.

To monitor the status of the LUN while it is being created, in the LUN Management node, refer to the Task Status column on the results pane. While the LUN is being created, the column shows the percentage of the LUN that has been completed. When the operation has finished successfully, the task status changes to Created.

If LUN creation fails, you can click the LUN entry in the Results pane to display failure information in the description area below it.