Multiprotocol storage arrays gain interest, adoption

Multiprotocol storage arrays, or unified storage, combine block and file storage access protocols. Interest due to cost savings, advances in technology and simpler management.

Multiprotocol storage arrays, which combine block and file storage access protocols, are gaining more interest and adoption by small- and medium-sized enterprises (SMEs) because they offer savings, advances in technology and simplify management.

The current industry-favorite term for multiprotocol storage arrays is unified storage, but it's also sometimes called modular, hybrid or federated storage as vendors seek to differentiate their products.

By any name, multiprotocol storage arrays are being purchased by more and more SME IT managers who are looking to reduce capital and operational expenses, as well as limit the number of IT and data storage administrators required to manage their companies' growing block and file storage requirements.

According to Terri McClure, an analyst at Milford, Mass.-based Enterprise Strategy Group (ESG), a fall 2008 ESG survey of 338 administrators with storage buying responsibilities found that 67% of them had multiprotocol storage implementations underway or were in the planning phases.

Smaller enterprises that had outgrown their legacy network-attached storage (NAS) or storage-area network (SAN) systems used to be the dominant buyers of unified storage. While those smaller organizations are still mainstays of the unified data storage market, server virtualization and the easy-to-use management interfaces of unified systems are contributing to interest from even smaller companies. Meanwhile, disk performance advances and capacity optimization technology are further propelling unified storage systems up the food chain into mid-market enterprises.

McClure's ESG survey found that the reason cited most often by storage managers for researching and considering unified storage systems was to reduce operational costs (62%), followed by reducing capital costs (37%). Interestingly, the numbers were almost identical for managers in enterprises with 1,000 employees or more, and those in mid-market companies with 100 to 999 employees.

Unified storage systems more adaptable to I/O needs

NAS systems typically handle data storage based on the Network File System (NFS) and Common Internet File System (CIFS) protocols, including audio, video and graphic files, as well as file shares and home directories. SAN solutions use Fibre Channel (FC) and iSCSI protocols, and support more unstructured data, including Microsoft Exchange and database records.

Traditionally, as a small enterprise matured, application growth and the need for advanced features used to force the organization into implementing separate file and block storage systems. This often resulted in them splitting up their data storage teams to maintain and administer these disparate systems.

But today's unified storage systems are more adaptable. Most of the unified systems offered by the leading companies can scale to handle mid-market I/O needs. Some multiprotocol storage systems even support solid-state drives (SSDs), which allow unified systems to match large-scale, monolithic systems I/O by I/O. And the inclusion of best-in-class capacity management features, such as thin provisioning, cloning, replication, compression and deduplication, will further narrow the performance and manageability gap. In addition, unified systems play nice with server virtualization technologies.

"As long as you can serve your I/O needs from a unified pool of storage," said Jeff Boles, senior analyst and director, validation services at Hopkinton, Mass.-based Taneja Group, "it can serve all of your storage needs very well."

Boles said NetApp is generally recognized in the industry as having first introduced unified systems. The company offers multiprotocol storage arrays that include all of the big-boy optimization features, a single storage management interface for all of the block- and file-level applications, and extensive virtualization support. Jeff O'Neal, NetApp's senior director for data center solutions, said every system NetApp sells is a unified data storage system, and "you can dial up and down your performance needs, capacity needs and availability requirements."

EMC Corp.'s Celerra NX4 and NS-series unified data storage boxes are also quite scalable, and include deduplication with compression, virtual provisioning, automated volume management, and VMware and Microsoft Hyper-V certification. The Celerra NX4 scales to 60 drives, the NS 120 can handle up to 120 drives, and the NS 480 and NS 960 support up to 480 and 960 drives, respectively. EMC's Clariion storage backs the NX4 and NS-series solutions.

Smaller data storage vendors are also getting in on the multiprotocol action and rolling out new products. In April 2009, OnStor Inc. introduced its Pantera LS 2100 series unified IP storage system. It incorporates Sun Microsystems Inc.'s Solaris Zettabyte File System (ZFS) and other open-source technology. Narayan Venkat, OnStor's vice president of marketing, said the LS 2100 series' lowest entry price point is $20,000, which includes ZFS hybrid storage pools, snapshots, cloning, replication, thin provisioning and self-healing capabilities. The system can combine SAS and Flash SSD drives for high performance, or SATA drives for high capacity.

According to the OpenSolaris.org website, ZFS is a pooled data storage model that doesn't use volumes or partitions. All of the linked file systems draw from a common data storage pool, but ZFS has a pipelined I/O engine. The combined I/O bandwidth of all of the devices linked to the storage pool is available to all file systems at all times.

In addition, all of the system operations are copy-on-write transactions, and every block is checksummed to prevent silent data corruption. ZFS also uses its own data replication model, called RAID-Z, which is similar to RAID-5 but uses a variable stripe width to eliminate the RAID-5 write hole. Like the NetApp, EMC and OnStor products, ZFS provides constant-time snapshots, clones and built-in compression.

Consolidation and simplification benefits

Larger, protocol-specific systems can't match the consolidation and simplification benefits unified systems offer. "The key thing, especially in this economy right now, is that users are looking for operational savings," ESG's McClure said. "And that's what unified storage gives them if they can leverage their IP expertise and not have to train someone."

Organizations that adopt multiprotocol storage arrays typically don't have to hire or train administrators because current unified systems have addressed the ease-of-use nightmares multiprotocol support may present. "In this environment, having a system that's really simple to use and allows people to manage multiple protocols without having to be an expert in any of them is something that does pay dividends," said Jason Schaffer, senior director of storage product management at Sun Microsystems Inc.

Renewed interest in multiprotocol pooled storage

Unified systems have come a long way since their introduction. Capacity optimization technologies such as virtualization, deduplication, thin provisioning, tiered storage and cloning are largely responsible for the renewed interest in multiprotocol pooled storage.

Server virtualization is a key initiative for many small- and mid-market enterprise IT administrators. Smallish organizations can use fewer physical servers to host multiple applications on virtual machines -- applications that may have very different storage requirements. "Unified storage makes a whole lot more sense if you've started localizing your apps because of the cost benefits that server virtualization can give you," Taneja Group's Boles said.

According to ESG's McClure, server virtualization support is quickly becoming a "check-box" requirement for data storage system buyers, and VMware certification is the leading option.

Deduplication, another feature of some multiprotocol storage arrays, is also becoming popular for primary storage environments. NetApp's O'Neal said his company provides deduplication that can be used for nearline or primary storage.

Boles believes there are still more possibilities for capacity optimization features in unified systems. "I think we're going to see some interesting combinations," he said. "It doesn't take much imagination when you see something like Gluster being built on top of ZFS as a half open-source, half private project. It's a scale-out storage solution."

GlusterFS is an open-source modular and stackable parallel cluster file system capable of scaling to several petabytes, according to Gluster. It aggregates various storage bricks over an InfiniBand RDMA or TCP/IP interconnect into one large parallel network file system. GlusterFS partners include Intel Corp. and Mellanox Technologies Ltd.

NAS gateways

In addition to multiprotocol systems, network-attached storage gateways are emerging as alternative systems to help companies consolidate legacy SAN block storage and NAS file systems.

According to ESG's McClure, however, you shouldn't consider them as the only alternative options. The ESG survey found that only 18% of storage managers planned to deploy or would likely deploy a unified NAS/SAN storage system instead of a NAS gateway. A surprising 40% said they would use both depending on the situation, and 41% would use a NAS gateway to front end SAN storage.

"I think a lot of unified storage has to do with the legacy systems," McClure said. "Users are clearly willing to consider gateways as a way to repurpose existing SAN storage and unify their storage infrastructure. For users who have legacy storage installed, they don't need to go out and buy another multimillion dollar system to drop into their data center."

In addition to its Pantera line of unified IP storage, OnStor provides a line of clustered NAS gateways. The company's Cougar 3000 and 6000 gateways are targeted at enterprise data centers and high-performance applications, while its Bobcat gateways are designed to address file services for enterprises' midrange performance needs.

Multiprotocol storage arrays may have new names and boast new technologies, but the value proposition -- lower cost, fewer administrators, better resource utilization and simpler management -- remains the same. In the current economic circumstances, those are words any organization would want to hear.

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