Chapter 6. Storage pools 219
Automatic internal configuration
By selecting Internal, you rely on automatically chosen parameters such as RAID type 
(traditional or distributed), stripe width, number of spares (for traditional RAID), number of 
rebuild areas (for distributed RAID), and number of drives of each class. The number of drives 
is the only value that can be adjusted when the array is created. Depending on the number 
and the type of drives that are selected for the new array, the RAID level automatically 
adjusts. Also, the system automatically assigns spare disks.
.
In the example given in Figure 6-38, the dialog box suggests that you to assign 9 drives out of 
the given 10 to RAID6 array, the remaining one is assigned as a hot-spare.
Figure 6-38   Assign Storage to Pool dialog
If you select two drives only, the system automatically creates a RAID-10 array, with no spare 
drive. For more control of the array creation steps, you can select the Internal Custom 
option.
By default, if sufficient candidate drives are present, the system recommends traditional 
arrays for most new configurations of MDisks. However, switch to Distributed RAID when 
possible, with the Internal Custom option. 
If the system has multiple drive classes (like Flash and Enterprise disks, for example), the 
default option is as follows:
1. Create multiple arrays of different tiers.
2. Assign them to the pool to take advantage of the Easy Tier functionality. 
Note: It is not possible to change RAID level or drive count of the existing array. If you need 
to change these properties, you must delete array MDisk and re-create it with the required 
settings.