EMC has upgraded its availability, performance and path management software to help customers stay connected while migrating data or virtualising their storage.

PowerPath is EMC's widely used performance and availability software that provides multi-pathing between servers and storage arrays. The host-resident software is being enhanced by the addition of a PowerPath Migration Enabler software module.

When the PowerPath software detects imbalances, it automatically tunes a storage-area network (SAN) by selecting alternate paths through which data can be routed. The software also combines multiple path I/O capabilities, automatic load balancing and path failover functions in a single software package.

PowerPath users include Hartford Hospital and Starwood Hotels & Resorts Worldwide.

"We were looking for failover in the beginning - we didn't know much about PowerPath's load-balancing capabilities," says Rich Kubrica, CIO at Hartford Hospital in Connecticut. "We wanted to make sure we wouldn't lose a network adapter or Fibre Channel host bus adapter. Our databases and clinical information system are growing and if a failover occurs, we can keep on running. It's critical that we have 100 percent uptime."

Kubrica's IT group uses PowerPath to protect the EMC Symmetrix and Clariion arrays in their environment. An EMC shop, the hospital also uses EMC's Symmetric Remote Data Facility Cluster Enabler to replicate data between its headquarters in Hartford and a disaster recovery site.

Athy Pandy, senior storage architect at Starwood Hotels, also manages a mixed Symmetrix and Clariion environment. "We put in PowerPath to ensure high availability of our server environment," Pandy says. "We also wanted to use its multipathing capability to manage failures and load-balancing."

The PowerPath Migration Enabler software allows other technologies such as array-based replication or virtualisation to eliminate application downtime during data migrations or implementation of storage virtualisation. Initially, the software will work with EMC's Open Replicator software and the company's Invista virtualisation technology. The software keeps storage arrays synchronised during data migrations with almost no impact to host resources. It also allows Invista to be deployed by encapsulating virtual volumes.

Both Kubrica and Pandy say they are evaluating the Migration Enabler plug-in. However the downtime required to deploy the software is an issue for Kubrica.

"One of our problems is that we really have to limit our downtime," Kubrica says. "Installing the Migration Enabler software requires downtime. Sometimes we will get downtime available once every other month. We've been talking about putting in Migration Enabler if we migrate from a Symmetrix DMX2000 to DMX3000 later this year."

"We are looking at evaluating the product," Pandy says. "We are expecting to do a lot of migration in the next year and will use the Migration Enabler to do the data migration. We are going to do multiple system downs in our data migration project, so the downtime doesn't concern us."

Each of the SAN vendors has its own multi-pathing software. EMC's competes with IBM's System Storage Multipath Subsystem Device Driver, Hitachi's Dynamic Link Manager, the Sun StorEdge Traffic Manager and HP's StorageWorks Secure Path. Unlike some of these systems, PowerPath works with EMC, IBM, Hitachi Data Systems and HP storage systems.

The PowerPath software, which was introduced in 1998, is used by tens of thousands of users, according to EMC. It just surpassed the 500,000-license milestone.

PowerPath Migration Enabler software, which starts at $14,640 per storage array, is a plug-in to PowerPath