HPP Enterprises P4000 SAN - Manual (Page 39)

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Configuring multi-site high availability with a single cluster
If your organization deploys multiple data centers in close proximity, communicating over low-latency,
high-bandwidth connections
4 , you can stretch a resource pool between both sites. In this scenario, an
entire data center is no longer a SPOF.
The stretched resource pool continuously constantly transfers pool status and management information
over the network. Status information is also maintained on the 356MB iSCSI shared volume.
To give VMs the agility to start on any host on any site, SRs must be synchronously replicated and
made available at each site. HP StorageWorks P4000 SANs support this scenario by allowing you to
create a divided, replicated SAN cluster (known as a multi-site SAN), as shown in Figure 32.
Note
Since storage is being simultaneously replicated to both sites, you should
ensure that appropriate bandwidth is available on the SAN.
Figure 32. Sample stretch pool configuration with multi-site SAN
Requirements for a multi-site SAN include the following:
 Storage nodes must be configured in separate physical subnets at each site.
 Virtual IPs must be configured for the target portal for each subnet.
4 The connection between sites needs to exhibit network performance similar to that of a single-site configuration.