Configuring a HyperSwap system

You can create a HyperSwap topology system configuration where each control enclosure that is used to access a volume is physically on a different site. Only certain models support HyperSwap topology. Verify your model type before you configure the system for a HyperSwap topology.

In a HyperSwap® configuration, each site is defined as an independent failure domain. If one site experiences a failure, then the other site can continue to operate without disruption. You must also configure a third site to host a quorum device or IP quorum application that provides an automatic tie-break in case of a link failure between the two main sites. The main site can be in the same room or across rooms in the data center, buildings on the same campus, or buildings in different cities. Different kinds of sites protect against different types of failures.

Sites are within a single location: If each site is a different power phase within a single location or data center, the system can survive the failure of any single power domain. For example, one node can be placed in one rack installation and the other node can be in another rack. Each rack is considered a separate site with its own power phase. In this case, if power was lost to one of the racks, the partner node in the other rack might be configured to process requests. The partner node can effectively provide availability to data even when the other node is offline due to a power disruption.
Each site is at separate locations: If each site is a different physical location, the system can survive the failure of any single location. These sites can span shorter distances, for example two sites in the same city, or they can be spread farther geographically, such as two sites in separate cities. If one site experiences a site-wide disaster, the remaining site can remain available to process requests.

If configured properly, the system continues to operate after the loss of one site. In the management GUI, the Modify System Topology wizard simplifies setting up HyperSwap system topology. After you configure HyperSwap topology, you can use the Create Volumes wizard to create HyperSwap volumes and copies for each site. In addition, the HyperSwap volume wizard automatically creates active-active relationships and change volumes to manage replication between sites.

There are two network configuration types for HyperSwap systems:

HyperSwap configuration without interswitch links: The most simple IBM® HyperSwap configuration is built by attaching each control enclosure directly to the Fibre Channel switches in the local and the remote production site. This configuration is done without using interswitch links (ISLs). For more details on the requirements for configuring HyperSwap without ISLs, see the Configuring topics in the Knowledge Center.
HyperSwap configuration with interswitch links: You can use interswitch links (ISLs) in paths between nodes to configure an IBM HyperSwap topology system. If the cable distance between the two production sites exceeds 100 km, potential performance impacts can result.For more details on the requirements for configuring HyperSwap with ISLs, see the Configuring topics in the Knowledge Center.

To launch the Modify System Topology wizard to configure HyperSwap, complete the following tasks:

In the management GUI, select Montoring > System.
From the Actions menu, select Modify System Topology.
Select Multiple Sites and click Next to launch the Modify Topology wizard.
On the Assign Enclosures, assign enclosures to the configured sites.
Click Next and complete the rest of the wizard to configure a HyperSwap topology for your system .
If hosts are not added to the system, review the summary and click Finish. Hosts must be added to the system and assigned to a site, before they can be mapped to a HyperSwap volume. Select Hosts > Hosts > Add Host to add hosts.
If hosts are already added to the system, the wizard prompts you to assign hosts to a specific site. Click Next.
If the system detects external storage systems, the wizard prompts you to assign these systems to specific sites. Fibre Channel and iSCSI attached external storage systems are supported in HyperSwap configurations. Fibre Channel attached storage systems are automatically detected in the management GUI. For iSCSI attached storage, you need to add external iSCSI storage system and specify the site for the external storage system. See Adding iSCSI external storage for details. You either specify a site for quorum disk management or use an IP quorum application to manage quorum disk that are used in tie-break situations. If a IP quorum application is detected on the system, the management GUI bypasses the quorum site configuration. Click Next.
Specify the bandwidth between sites in the HyperSwap configuration. You can allocate the amount of bandwidth that background copy operations can use to not interfere with host I/O. For guidelines on setting these values, see Background copy bandwidth. Click Next.
Review the configuration summary and click Finish.