Add a disk to your RAID via MDSM

This tutorial explains how to add one or several disk(s) to the RAID via MDSM software for the PowerVault disk arrays. 

Note: This article is part of the Dell PowerVault knowledge library, available here

Note: Important: The addition of one or several disk(s) in an existing RAID can take up to several hours (according to the type of RAID and the size of the disks) because of the raid parity recalculation. A production shutdown is recommended to perform this procedure. It is also highly recommended to do a complete backup of the present data on the array.

Prerequisites:

• MDSM must be installed and the array must be accessible via this software.
• The array must be in an optimal state for this procedure.
• Before starting, insert the disk(s) to be added in a free storage location of the PowerVault array. 

Note: It is not possible to add a different topology disk in an existing RAID. (SATA or SSD disk in a SAS RAID for example)

Steps:

1. Launch MDSM and select the corresponding PowerVault array. Make sure that its state is "Optimal" (see image below).
   
   Figure 1: MDSM Devices view showing state
    
2. Double click on the array to access the matrix manager.
3. Click on Logical and select the volume RAID which has to be extended.
   
   Figure 2: MDSM Logical tab
    
4. There are two possibilities to add a disk by using the interface:
   1. Click on Disk Group, select Add free storage and validate.
      OR
   2. Right click on the RAID, and then select Add free storage (physical disks).
       
5. In the following menu, select one or several disk(s) to be added, and then click Add.
   
   Figure 3: Add disk dialogue
6. A message will indicate that the procedure can last several hours and then you will have to reconfirm the launch of the operation.
    
7. You will notice that an operation is in progress by looking back at the Summary tab.
   
   Figure 4: MDSM Summary tab showing operation in progress
    
8. Once this procedure is finished, go back to the Logical tab to check if the size of your RAID has been extended. 
   
   Figure 5: MDSM Logicall tab, confirming capacity has increased