Chapter 3. Planning 65
– The cluster can be connected to a maximum of 1024 WWNNs. The general practice is 
that:
 EMC DMX/SYMM, all HDS, and SUN/HP HDS clones use one WWNN per port. 
Each port appears as a separate controller to the Storwize V7000.
 IBM, EMC CLARiiON, and HP  use one WWNN per subsystem. Each port appears 
as a part of a subsystem with multiple ports, up to a maximum of 16 ports 
(WWPNs) per WWNN.
However, if you plan configuration that might be limited by the WWNN maximum, verify 
the WWNN versus WWPN policy with the back-end storage vendor.
3.9  Internal storage configuration
For general-purpose storage pools with various I/O applications, use the storage 
configuration wizard in the GUI. For specific applications with known I/O patterns, use CLI to 
create arrays that suits your needs.
Use DRAID 6 as the default RAID level for internal arrays. DRAID 6 outperforms RAID 5. 
Workloads that used to be placed on RAID 10 arrays now are usually on SSD drives.
For more information about internal storage configuration, see IBM System Storage SAN 
Volume Controller and Storwize V7000 Best Practices and Performance Guidelines, 
SG24-7521.
3.10  Storage pool configuration
The storage pool is at the center of the many-to-many relationship between the MDisks and 
the volumes. It acts as a container of physical disk capacity from which chunks of MDisk 
space, known as extents, are allocated to form volumes presented to hosts.
MDisks in the Storwize V7000 are LUNs that are assigned from the back-end storage 
subsystems to the Storwize V7000. There are two classes of MDisks: managed and 
unmanaged. An unmanaged MDisk is a LUN that is presented to IBM SAN Volume Controller 
by back-end storage, but is not assigned to any storage pool. A managed MDisk is an MDisk 
that is assigned to a storage pool. An MDisk can be assigned only to a single storage pool.
Storwize V7000 clustered system must have exclusive access to every LUN (MDisk) it is 
using. Any specific LUN cannot be presented to more than one Storwize V7000 cluster. Also, 
presenting the same LUN to a Storwize V7000 and a host is not allowed. 
One of basic storage pool parameters is the extent size. All MDisks in the storage pool have 
the same extent size, and all volumes that are allocated from the storage pool inherit its 
extent size. 
There are two implications of a storage pool extent size:
/SM590000Maximum volume, MDisk, and managed storage capacity depend on extent size (for more 
information, see this IBM Support web page). The bigger extent that is defined for the 
specific pool, the larger is the maximum size of this pool, the maximum MDisk size in the 
pool, and the maximum size of a volume created in the pool.
/SM590000Volume sizes must be a multiple of the extent size of the pool in which the volume is 
defined. Therefore, the smaller the extend size, the better control over volume size.