Systems combining block and file storage maximize benefits of server virtualization.
The data center of the future looks an awful lot like data centers of the past in one important respect: storage demands. While the trend toward server virtualization and consolidation is transforming the way data centers are being designed, built and managed, rampant data growth continues to be a limiting factor.
In its annual “Digital Universe” study, EMC projects a nearly 45-fold annual data growth by 2020. Data growth was cited as the No. 1 data center hardware infrastructure challenge in a recent Gartner survey of representatives from 1,004 large enterprises in eight countries.
“While all the top data center hardware infrastructure challenges impact cost to some degree, data growth is particularly associated with increased costs relative to hardware, software, associated maintenance, administration and services,” said April Adams, research director at Gartner. “Given that cost containment remains a key focus for most organizations, positioning technologies to show that they are tightly linked to cost containment, in addition to their other benefits, is a promising approach.”
In order to drive down costs and reduce operational complexity, organizations virtualizing their data centers and beginning the journey to the cloud require a storage infrastructure that is both simple and efficient. Unified storage delivers on both counts.
Unified storage is the combination of block- and file-based storage in the same system with common management. These multiprotocol systems can be attached to servers via IP and/or Fibre Channel.
The Road to Unification
Unified storage is an evolving technology, but not a new technology. A variety of vendors have taken stabs at providing block- and file-oriented storage in a single box since the late 1990s. Some of the earliest attempts involved simply putting two machines together in a single enclosure and then creating a GUI to handle management of both.
Next came NAS gateways, which used a NAS box as an entry to SAN storage. In this setup, a NAS box provides file-based access to applications via a LAN port, and then stores the data on a block-oriented storage array that can be accessed across the SAN. While this approach accommodates both block and file protocols, it has some disadvantages. One of the major problems is that data must be transferred twice — once across the NAS Ethernet connection and again across the Fibre Channel or IP SAN — which adds to I/O latency. Another issue is that the management of NAS gateways continues to be separate from the management of SAN arrays.
More recent unified storage platforms leverage virtualization technology to offer a much deeper integration of file- and block-based storage. A file system performs I/O to disk blocks using a common virtualized disk-volume engine. Virtualization allows administrators to create a seamless pool of unified storage and enables transparent data movement for tiered storage.
While NetApp introduced unified storage to the market several years ago, it is now available from most storage vendors. Many of these solutions include features such as data replication, incremental snapshots and remote mirroring that contribute to robust business continuity capabilities.
Aligning Storage with Virtualization
IT organizations face growing pressure to transform the data center to meet increasing demands for wider access to information, transactions and services. To a great degree, this means creating a technology infrastructure composed of virtualized computing and networking. By breaking the relationship between applications and the IT systems on which they run, virtualization frees system administrators from providing specific hardware with static configurations.
However, many organizations have found that the benefits of virtualization are offset by increased storage complexity and expense. For example, the creation of hundreds or even thousands of virtual server image files often leads to massive storage waste. Because each of these images is typically many gigabytes in size, the total storage required in virtual environments can be 30 percent more than in an equivalent physical environment. As a result, virtual machine sprawl increases operational overhead and compromises storage utilization efficiency and overall business agility.
Unified storage improves utilization by allowing organizations to consolidate and virtualize storage across storage protocols, environments and mixed storage platforms. Combinations of block storage (Fibre Channel or iSCSI) and file storage (NAS systems with CIFS or NFS) can be managed via a common set of features such as snapshots, thin provisioning, tiered provisioning, replication, synchronous mirroring and data migration — all from a single user interface. This shift toward a shared infrastructure enables organizations to achieve storage utilization rates of 85 percent or more, compared to the sub-50-percent rates in standalone storage silos.
“IT managers are looking for storage solutions that not only deliver immediate value, but also enable flexibility and growth over time, so that storage can adapt to changes in an organization's applications, user needs or business demands,” said Mark Peters, senior analyst at Enterprise Strategy Group. “Storage solutions that are both virtualized and unified are ideal to address the needs for both storage flexibility and data growth.”