LUN Expansion on EMC CX4-240

This blog shows step by step procedure to expand an existing SAN LUN on a Windows 2003 server presented from an EMC CX4-240 storage array. In this example, I expanded a 2 TB LUN on a Windows 2003 server to 3 TB.

Pre-requisites:-

• EMC Unisphere client
• Login credentials for the Unisphere client
• Admin Login credentials for the Windows server (needed to run diskpart)
• The OS should support the LUN expansion (Different operating systems have limitation for the file system size so please check the operating system guide for maximum supported disk size)

                                                                     

1. As you can see in the diagram below, the existing LUN size is 2 TB. In order to expand the LUN beyond the 2 TB limit on a Windows 2003 server, make sure that the disk type is GPT (GUID Partition Table).

2.  Login to the EMC Unisphere Client and select the RAID Group that contains the LUN. In our example here, it is RAID Group 15 and LUN 150.

3. Right click the RAID Group and select “Create LUN” option.

4. In the new window that opens up, type the “User Capacity” as 1000 GB. You can either specify the LUN ID or can leave it to the default value. Click apply and close the window.

5. So now we have a new LUN (LUN 0 in our example) of capacity 1 TB.

6. After the new LUN has been created, right click the original LUN that you wanted to expand (LUN 150 in our example) and select “Expand” option.

7. The “Expand Storage Wizard” will open up. Click “Next” to begin.

8. There are two ways in which the new LUN can be used to expand the current LUN capacity.

a.       Striping: The data on the existing LUN is stripped across the new LUN.

b.      Concatenation: It simply adds additional capacity to the existing LUN without stripping the data across the two LUNs.

Since my aim is to just gain additional capacity on my existing LUN, I will choose the “Concatenation” option.

9. Click “Next”

10 .   Click “Next” again.

11.   In the new Window that opens up, click “Yes”. Unisphere will give this warning message if the new LUN size exceeds 2 TB.

12.   In the next Window that opens up, mention the size of the new Concatenated LUN.

 13.   Enter the settings for the new LUN (I usually leave them to default)

14.   On the Summary page, click “Finish”.

15.   Now login to the server where you wanted to expand the disk. Open Disk Management. Right click disk management and select “Rescan Disks”.

                                              

 16.   You will see some (1 TB ) unformatted capacity added to the existing 2 TB LUN.

  17.   Open command prompt window on the server and run the following commands.

In our example, we are expanding G: from 2 TB to 3 TB.

a.      List disk

b.      Select disk <disk #>, where <disk #> is the disk number of the LUN that we want to expand. (Disk 3 in our example)

c.       Select volume <volume #>, where <volume #> is the volume that we want to expand. (Volume 1 in our example)

d.      Type “Extend”

e.       You will see that the size of the new LUN is now 3 TB.