Software Increases Storage Pooling Efficiency
VARs and system integrators should not feel limited to recommend only a single type of storage pool to their customers. NAS, SAN, or RAID pools can be deployed to meet the needs of different types of applications.
Most companies agree that storage is getting out of control - both in terms of the rapid increase in demand for storage - and in the spiraling costs of management. Improvements in technology and the decreasing physical cost of disks have reduced the up front acquisition cost of storage. However, management costs continue to skyrocket, with industry analysts estimating that anywhere from 30% to 90% of storage TCO (total cost of ownership) is associated with management.
Part of the high cost of management is due to the widely distributed nature of, and inefficiencies associated with DAS (direct attached storage), which comprises the vast majority of the current storage installed base. A recent report from Dataquest estimates current disk usage rates at 30% to 60%, with well-performing companies targeting 85% to 90%. Further, within most organizations, storage capacity allocation is typically unbalanced - applications that have high storage demands may be starved for capacity, while other applications have excess capacity that cannot be easily shared. In order to alleviate the management problems associated with DAS, as well as to more intelligently balance capacity, many VARs and storage integrators are recommending consolidation of storage resources into pools, with centralized management capabilities.
Storage Pooling Increases Efficient Storage Usage
Storage pools provide multiple advantages to users, including ease of management, improved capacity utilization, and enhanced server efficiency. Since a storage pool is managed as a single logical unit, management is simpler relative to the effort required for the management of DAS. Since resources in a pool are dynamically shared, applications with high demand for storage have greater capacity to draw on, while excess storage capacity is not wasted on applications with lower demands. Therefore, capacity utilization increases efficiently. As capacity needs increase, additional storage can be transparently added to a storage pool, without impacting front-end applications. Since storage is separated from servers, these servers are freed to service the needs of clients and applications - rather than the needs of storage.
There are several ways to create storage pools, but one of the most cost-effective and efficient ways is to use storage virtualization and storage management software to create LAN (local area network)-based virtual storage pools. Using these software solutions, the pooled storage resources appear to the LAN application or client as a single logical resource, regardless of the actual physical location of the devices. This masks the underlying complexity of the distributed storage architecture, while leveraging the investment in existing storage assets. Furthermore, since applications are shielded from changes in the storage environment, capacity can be transparently added and dynamically allocated for all applications utilizing the consolidated storage pool.
SANs Are Not The Only Answer
While many people consider SANs (storage area networks) to be the ultimate in storage pooling, SANs are not the correct fit for every situation or application. SANs have many advantages, including consolidation of storage resources, high availability, performance, and reducing or eliminating the backup window problem. However, the adoption of this technology has been slow, partially due to concerns about interoperability between various components, lack of expertise in the new technology, and, most significantly, cost. While the advent of IP-based SANs may alleviate some of these concerns, a SAN still represents a significant capital investment for many organizations.
In many cases, other types of storage pools can fulfill an immediate storage need without requiring the large capital expenditure typically necessary for SAN implementation. Software solutions can be used to create pools of RAID (redundant array of independent disks), which can serve applications that have low tolerance for latency, such as databases. When an organization is ready to deploy a SAN, a RAID pool can easily migrate into that environment. Similarly, secondary storage devices, such as tape libraries and optical jukeboxes, can be aggregated to serve the storage and access needs of users and applications which have a higher tolerance for latency, such as long-term storage, archival, or medical imaging. In addition, the use of storage virtualization technology to create LAN-based storage pools can be an interim step in a transition from a DAS to a SAN environment. A customer's existing storage resources can often be used to create storage pools, thus extending the return on investment of their current storage technology, while at the same time, reducing the cost and complexities of managing that investment.
Don't Let NAS Cause The Same Problems As DAS
NAS (network attached storage) is one of the fastest growing storage technologies - with over 62,000 units sold in 2000 according to Dataquest. This represents a 133% increase over units sold in 1999. Part of the reason for this rapid growth is the essential promise of NAS - easy-to-use, plug and play storage for multiple servers in a network, which can relieve the management burden of DAS for those servers. Another reason for NAS popularity is that the devices range in size from several hundred gigabytes to multiple terabytes and range in cost from under $2,000 to more than $500,000. This flexibility complements the budgets and storage requirements of many organizations.
Like SANs, however, NAS devices are not suitable for every situation and application, especially those sensitive to latency, such as databases. Also, when multiple NAS devices are present in a storage environment, administrators can experience similar management difficulties as experienced in a DAS environment. To overcome the physical, distributed management challenge, system integrators and NAS hardware vendors are using software solutions to aggregate (logically combine) multiple NAS devices into a centralized virtual storage pool. This allows an organization to use multiple, less expensive NAS devices in an aggregated configuration, compared to a single, more expensive, larger NAS. The higher capital expenditure of the single large NAS device can be avoided through a more efficient "pay as you grow" methodology, especially important in times of tighter fiscal budgets. Finally, for organizations that have already deployed NAS, these advanced software solutions can allow them to leverage their existing investment in NAS, while further reducing management overhead.
Multiple Needs Filled With Multiple Pools
VARs and system integrators should not feel limited to recommend only a single type of storage pool to their customers. Multiple pools can be deployed to serve the needs of different types of applications - RAID pools or SAN when latency is a concern; NAS pools when latency is less critical, but access speed is important; and tape library and optical jukebox pools when long-term archival is critical, while access speed is even less important. Ideally, when creating a storage pool, system integrators should try to leverage a customer's existing storage assets. Integrators should choose storage management software solutions that will not only help their customer today, but grow with them as their storage needs grow - as they move from DAS to NAS to SAN. Finally, when selecting a software solution to pool NAS, it is important to ensure that the software is capable of simultaneously aggregating NAS devices that run under various different operating systems (i.e., Windows 2000, Linux, BSD, proprietary, etc).
Storage is meant to serve the needs of applications, so integrators should design the storage architecture with applications in mind. Therefore, integrators should seek out software solutions to centralize and streamline the management of storage pools, while ensuring that transparent application access is maintained.Questions about this article? E-mail the author at firstname.lastname@example.org.