Planning for high availability

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You must plan which system topology to use and if you intend to link with partner systems at other sites.

Before you begin

Choose one of the following system topologies:
  • The standard topology, where all control enclosures are at the same site. Higher availability can be achieved by using Metro Mirror or Global Mirror to maintain a copy of a volume on a different system at a remote site.

    For more information about planning for Metro Mirror and Global Mirror using IP networks without the necessary Fibre Channel infrastructure, see Configuring IP partnerships in the Related concepts section.

  • The HyperSwap® topology where each I/O group and its managed disks are at a different site. Active-active remote copy relationships mean that a volume can be active on two I/O groups so that it can immediately be accessed by using the other site without loss of performance. To meet the planning requirements of HyperSwap topology must ensure that the following steps are completed:
    • There must be another I/O group and managed disks at another site.
    • There must be managed disks at a third site for quorum disks. As an alternative to quorum disks at a third site, you can use IP quorum.
    • Before the system topology can be set to HyperSwap, the site attribute must be set to:
      • 1, 2 or 3 for each controller
      • 1, 2 for each host
    • The system must be set to HyperSwap topology before HyperSwap volumes can be created.
    • Ensure availability of enough available capacity for the HyperSwap change volumes to grow in the storage pools on each site. During resynchronization of a HyperSwap volume, the capacity that is used by the change volume increases to the same amount of storage as the difference between the old copy and the new copy. This capacity is released when the resynchronization process is completed.