AIX > Administrator > High Availability

Expanded Capabilities

The new PowerHA for AIX offering addresses disaster recovery, cluster management and security.

Illustration by Henk Dawson

With PowerHA for AIX* (HACMP V5.5.0.0), IBM addresses three key areas that affect IT high availability (HA) and disaster recovery (D/R) operations—D/R, cluster management and security.

PowerHA for AIX, part of the new branding strategy for Power* Systems, is the flagship Power Systems HA package for UNIX* environments. HACMP, which has been in the market for more than a decade, is widely deployed across the globe. With each release of the product, IBM developers add new function and enhance the robustness of existing function. A major benefit of the PowerHA solution is that it’s developed, tested and integrated by the same engineers who develop the AIX operating system. This new version of PowerHA for AIX was announced Oct. 7.

Disaster Recovery With PowerHA/XD

It’s becoming increasingly clear that IT shops are looking for solutions that not only provide recovery at a remote location, but also provide continuous data recoverability. Traditional D/R solutions have been based on restoring operations at a remote facility from tape. The problem with this approach is that you’re restoring to the last save image and therefore are exposed to data loss. Your recovery point objective (RPO) could be days. It’s one thing to use an outsourcing operation for recovery from tape, but it’s an entirely different matter when you need continuous data replication to a remote facility to enable an RPO of as close to zero as feasible.

D/R outsourcing options typically involve multiple clients with access to one physical system. Normally, IT shops will conduct an annual test that demonstrates their ability to recover from tape at this remote location. The need for continuous data recoverability with an RPO approaching zero necessitates continuous real-time data replication to a remote location, which in turn means you need dedicated system resources. This need spurs many clients to investigate in-sourcing D/R operations.

As I mentioned, the core requirements for a modern D/R solution include geographic dispersion and an RPO approaching zero. To accomplish this, you need a replication approach that is asynchronous to the application state so you don’t impact application performance due to the latency associated with a synchronous replication approach. In other words, you want synchronous replication for data center operations but asynchronous replication for geographic dispersion.

PowerHA for AIX has an optional feature called PowerHA/XD (for extended distance) that now offers support for Geographic Logical Volume Manager (GLVM) async mode and SAN Volume Controller (SVC) Global Mirror. GLVM, which will GA in the first quarter of 2009, is the native AIX volume manager deployed over IP. With V5.5.0.0, IBM announced support for GLVM async mode, which means you can readily deploy your own in-house D/R solution with geographic dispersion and avoid the latency penalty (or the outsourcing fees) inherent in a synchronous solution.

If your IT shop is deployed on the IBM TotalStorage* SVC technology, you can choose Global Mirror as your replication method managed under the control and management of PowerHA/XD. Global Mirror provides asynchronous mirroring while its sister option, Metro Mirror, provides synchronous mirroring.

WebSMIT Enterprise view enables you to observe the status of all of your clusters from a single, consistent interface.

Steve Finnes is the System i Business Continuity product manager with IBM. Steve can be reached at

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