Hitachi Data Systems Corp., (HDS), a wholly owned subsidiary of Hitachi Ltd., has announced that its TagmaStore Universal Storage Platform can now virtualize all EMC Corp. Symmetrix systems, adding functionality to these products that EMC does not currently offer.
Specifically, HDS claims the TagmaStore provides EMC DMX 800, 1000, 2000, 3000 and Symmetrix 3000, 5000 and 8000 series users with the ability to reduce operational costs and software licensing fees, and provide software functionality, such as asynchronous remote copy and logical partitioning. EMC Clariion CX series storage systems will be supported at the end of January, Hitachi said.
"Customers can now revitalize their existing EMC storage systems with the latest Hitachi software by using the virtualization layer within the Universal Storage Platform to 'map' new functionality to all externally attached storage systems," said Yoshinori Okami, general manager of storage systems development at Hitachi Ltd.
"This means you can take a Clariion, virtualize it, and enable it to store mainframe data on SATA disks; you can take a DMX, attach it to a Universal Storage Platform and virtualize it as part of a logical partition, assigning dedicated resources to an individual application; you can move data from Clarions to Symmetrixes and back," he said.
The "V" wars
Since the announcement of the TagmaStore in September 2004, HDS has completed virtualization testing for Hewlett Packard Co., IBM, Sun Microsystems Inc., and EMC storage systems.
However, its approach to virtualization is up for debate. The TagmaStore combines a massively parallel, crossbar switch with a storage controller inside a RAID array to enable a heterogeneous view of both host and storage resources.
Its critics argue that this method is a proprietary implementation, which defeats the purpose of virtualization. In other words, users are stuck with Hitachi's tools to run all their functionality and must scrap any investment in software on other attached storage.
Futhermore, some analysts think the issue of cache coherency between the switch and the storage controller could be a problem. "Keeping data in two places consistent when you are performing thousands and thousands of transactions could be hard to support," said Arun Taneja, founder and analyst with the Taneja Group. He said he believes this problem can be avoided with an intelligent switch-based approach as the data is never stored, but pushed through the network at wire speed until it reaches its target, avoiding the potential for bottlenecks. This is the approach EMC is taking with its Storage Router (not yet available).
Hu Yoshida, chief technology officer at HDS, points out that the Storage Router configuration involves cracking open every data frame being moved through the system in order to know where to send it. He said this will add latency to the system and burdens the already over-taxed network resources.
The jury is still out on which approach is best, and most analysts think users should experiment this year before putting any of this gear into mission-critical environments. In the meantime, until EMC releases its product, HDS is in the enviable position of being one of the first major companies to market with heterogeneous virtualization support. IBM also supports EMC, HP and HDS arrays with its SAN Volume Controller (SVC) virtualization software.