Chapter 3. Planning 47
For clustered Storwize V7000 (two or more I/O Groups) systems that do not virtualize 
external storage (and therefore cannot place a quorum disk on an external MDisk), 
generally use IP quorum device to reduce the risk of outage in case of a split-brain cluster.
For HyperSwap systems, it is recommended to have at least two independent IP quorum 
devices defined to prevent the active quorum device placement in one of sites that hold 
Storwize V7000 HyperSwap storage components. Also, make sure that at least one 
quorum drive is in each site.
The IP quorum device acts only as a tie breaker in case of a split-brain cluster scenario. 
Quorum disks are still required to store cluster state.
/SM590000Failure domain sizes
Failure of an MDisks takes offline the entire storage pool that contains this MDisk. To 
reduce the effects of an MDisk failure, consider reducing the number of back-end storage 
systems per storage pool, and increasing the number of storage pools and reducing their 
size. This configuration limits the maximum performance of the pool (fewer back-end 
systems to share the load), increases storage management effort, can lead to less 
efficient storage capacity consumption. It also might be subject to limitation by system 
configuration maximums.
For internal storage, you might be able to define arrays in such a way that they can survive 
an expansion drive failure. However, such array design might restrict performance, 
available array sizes and RAID levels, depending on your hardware configuration.
/SM590000Consistency
Strive to achieve consistent availability levels of all system building blocks. 
3.3  Connectivity planning
IBM Storwize V7000 offers a wide range of connectivity options, both to back-end storage and 
to hosts. They include Fibre Channel (FC) SAN (8 and 16 Gbps, including direct attachment 
for some purposes), iSCSI (with 1 Gbps and 10 Gbps ports, depending on hardware 
configuration), and FCoE connectivity on 10 Gbps ports.
Storwize V7000 supports SAN routing technologies between Storwize V7000 and storage 
systems if the routing stays entirely within Fibre Channel connectivity and does not use other 
transport technologies, such as IP. However, SAN routing technologies (including FCIP links) 
are supported for connections between the Storwize V7000 and hosts. The use of 
long-distance FCIP connections might degrade the storage performance for any servers that 
are attached through this technology.
Table 3-1 lists the fabric type that can be used for communicating between hosts, nodes, and 
back-end storage systems. All fabric types can be used at the same time.
Table 3-1   Storwize V7000 communication options
Communication type Host to Storwize 
V7000
Storwize V7000 
to storage
Storwize V7000 
to 
Storwize V7000
Fibre Channel (FC) SAN Yes Yes Yes
iSCSI (1 GbE or 10 GbE) Yes Yes No
iSCSI (25 GbE) (RDMA iSER) Yes No Yes
FCoE (10 GbE) Yes Yes Yes