Using the CLI 9.2.3 Creating the MDisk arrays or discovering unmanaged MDisks Using the GUI Chapter 9. IBM Storwize Family and SAN Volume Controller  129 Note:  If you want to determine the drives that will be spare, you can manually select  them before this step and mark them  spare  in the  Use  column. For that, right-click the  drive and select  Mark As  followed by the  spare  option. A good practice is to select one  spare drive for each drawer and type of drive. To accomplish this task in the GUI, complete the following steps: Note:  Storwize V3700 allows only internal disks; the SAN Volume Controller allows only  external disks. When you use the Storwize V5000 or V7000 server, you can use internal or external disks to  create MDisks. These steps can also be done by using the CLI, as shown in Example 9-1.  Example 9-1 Creating a pool using the CLI # svctask mkmdiskgrp -ext 256 -warning 100% -name UD_pool 1. Hover the cursor over the  Pools  icon. The Pools menu opens (Figure 9-4).  2. To create an MDisk with internal disks, click  Internal Storage  to display the list of  candidate internal disks. Select the drive class that you want to configure, for example,  SAS disks for metadata and NL_SAS (or Serial Advanced Technology Attachment, also  known as SATA) for user data. Then, click  Configure Storage  (Figure 9-5 on page 130). Figure 9-4 Pools menu