Analysts and vendors say there will be a steady stream of technical enhancements to midrange arrays this year, such as a greater use of ATA disks, a shift to lower-priced SATA drives, the adoption of SAS drives as they become available, and the combination of different disk drives such as Fibre Channel, SCSI, ATA/SATA and serial-attached SCSI (SAS) in the same cabinet. In addition, a few vendors have started to add iSCSI, thin provisioning (dynamic capacity allocation during write operations) and n-way scalability, which requires support for more than two controllers.
Storage vendors will continue to use software to differentiate their midrange and enterprise systems. But software differences are narrowing fast, as most midrange storage systems already have replication, snapshot and sophisticated management capabilities. The only debate is whether these capabilities rival those of enterprise systems. "For now, there are still things an EMC Symmetrix can do that an EMC Clariion can't," insists Mike Karp, senior analyst, Enterprise Management Associates, Boulder, Colo.
"We have replication on the Clariion and the Symmetrix, but the software is more mature, more robust on the Symmetrix," notes Krone, who adds that "the Symmetrix can handle more clients -- thousands rather than hundreds -- and support more simultaneous applications -- dozens rather than just a couple." The Symmetrix also has greater depth of redundancy, enabling it to absorb multiple component failures at different points simultaneously. Mainframe connectivity is another feature that distinguishes monolithic from most midrange arrays.
Software differences, however, are being further obscured with the introduction of IBM Corp.'s DS6000 array, a modular storage system that bridges midrange and enterprise storage. "The DS6000 has the same microcode as Shark [the former code name for IBM's high-end Enterprise Storage System (ESS) line]," says Cindy Grossman, director of disk marketing for IBM Storage Systems. By running the same microcode, the DS6000 can use the same advanced software IBM provides for its ESS products. "Now modular can equal enterprise," she says.
This may impact the entire storage industry. "That IBM ported high-end enterprise code to a lower cost modular platform is significant. Users don't want to manage different systems," says Rob Schafer, senior program director at the Meta Group, Stamford, Conn. Other vendors may be forced to follow, further erasing operational distinctions between modular and enterprise systems while retaining lower midrange pricing.
Pricing continues to be a key differentiator for midrange storage. Garrett sees the adoption of SATA drives leading to price reductions of as much as 25% for modular storage.
Despite increased disk capacity, faster disks, higher performance, increased flexibility and sophisticated software capabilities, midrange storage may still not be ready to replace enterprise storage for all applications. "Modular storage will take over at the enterprise level when the services are as capable as those at the high end," says Karp. With high-end microcode now available on modular storage, that day may come sooner rather than later.
About the author: Alan Radding is a frequent contributor to Storage magazine.