By Kevin Komiega
—Hewlett-Packard rolled out three new versions of its midrange disk arrays this week with the introduction of the HP StorageWorks Enterprise Virtual Array (EVA) 4100, 6100, and 8100 models. Each array outpaces its predecessors in performance and uses a new software technology that can shrink or grow volumes on-the-fly.
Patrick Eitenbichler, director of marketing for HP's StorageWorks division, says the new EVA models are 24% faster than previous generations, feature additional redundancy between disk controllers and drives, and provide more-efficient capacity utilization through the use of EVA Dynamic Capacity Management (DCM) software.
Much like thin-provisioning technology, DCM can double capacity utilization rates. The software leverages the Virtual Disk Service (VDS) volume shrink feature in Microsoft Windows Server 2008 to continuously monitor storage utilization rates and automatically grow or shrink host volumes to match application requirements, thereby reducing the necessity for ongoing storage administration and helping to reduce "stranded" storage.
"From the perspective of the EVA, the software doesn't trick the application into thinking there is more physical storage present than there is, like you would see in most implementations of thin provisioning. The volume size the application sees through DCM is the actual size of the volume," says Eitenbichler. "DCM technology and thin provisioning are really two different ways toward getting similar results of increased utilization and lower cost."
Enterprise Strategy Group senior analyst Tony Asaro explains that despite the similarities, thin provisioning and DCM are two completely different technologies. Thin provisioning enables users to create large virtual volumes, but only consume the amount of capacity used by actual data, according to Asaro. With DCM, all of the storage allocated would be unavailable to other applications.
"The value of DCM is that you can easily grow or shrink a volume online," says Asaro. "Instead of creating a 2TB volume, you can create a 500GB volume. If you experience rapid data growth it's easy to increase the size of the volume, or if you find that your data doesn't grow materially you can decrease the volume."
Unlike thin provisioning, DCM requires the operating system and storage system to be integrated.
"They are two different technologies that both provide users with a more-efficient way to provision and utilize capacity. They are actually complementary," says Asaro.
Eitenbichler claims the combination of DCM with other hardware and software features, such as VSnap, will help users optimize drive utilization, eliminate unnecessary disk purchases, and shrink the power, cooling, and space requirements.
The disk arrays are available in a number of configurations and capacity points, from the EVA4100 Starter Kit for small SANs up to the 120TB EVA8100. The 4100, 6100, and 8100 support Fibre Channel and iSCSI connectivity, remote replication with EVA Continuous Access, and both block- and file-level I/O.