Service provider takeaway: Many service providers know the benefits of server virtualization, but its effectiveness depends on the storage performance of its underlying servers. Service providers can use the power of thin provisioning/storage virtualization to improve the performance of virtual machines.
As server virtualization continues to move into the mainstream, it has begun to drive storage administrators to look for better ways to provision and manage their storage while containing costs and ensuring the high storage performance that virtual servers require.
With traditional storage provisioning, storage administrators define the amount of storage that an application will require, with that full amount of storage being reserved from the time the application is configured. Large amounts of storage thus go unutilized until the application actually writes to it, wasting expensive storage resources.
Thin provisioning, on the other hand, allows physical storage to be reserved only when the data is written, rather than when the application is initially configured. Requests for additional storage are made against a pool of storage, which can be monitored and managed by the storage administrator -- as more storage is needed, it can be added to the pool on demand. Thin provisioning therefore avoids the costs of unused, idle storage and increases the utilization of the storage devices that are being used.
Using thin provisioning to avoid overbuying storage also has a secondary benefit to your customers: It reduces power and cooling costs, since unused idle storage devices still require power and cooling. In this age of green computing and rising energy costs, this is a real bonus.
Thin provisioning capabilities are available as an integrated part of certain hardware-based storage solutions, or as a software solution. Multiple storage vendors -- including 3PAR, Compellent, LeftHand Networks, Network Appliance and Hitachi Data Systems -- now include thin provisioning either as part of their base offering or as an option. DataCore's SANMelody and higher-end SANSymphony products offer software-only solutions that work across a broad range of storage hardware -- supporting all major storage arrays -- creating a virtual storage pool that is hardware-independent. Thin provisioning is offered as part of its management capability, allocating only what is written and then allowing more storage to be added to the pool as the storage allocation grows.
Storage virtualization meets server virtualization
Storage virtualization has received increased interest due to server virtualization. Since server virtualization consolidates multiple virtual servers onto one physical server, it puts greater stress on the resources of that physical server by driving up its input/output (I/O) activity. As the performance of the physical server degrades under pressure from more virtual machines, it has a direct impact on the performance of the applications running on the virtual servers. Therefore storage performance becomes a critical success factor for server virtualization.
Together, storage virtualization and server virtualization bring forward the reality of a virtualized infrastructure where hardware is added as needed and server, storage and network resources can be provisioned on demand. As an example of the partnership between storage and server virtualization, DataCore has added support for Xen, Microsoft Virtual Server and Virtual Iron to its previous support for VMware.
Also like server virtualization, storage virtualization capabilities are extending down to small and medium-sized businesses (SMBs). DataCore's SANMelody product provides the ability to take multiple servers and their direct-attached storage and pool them to act as a SAN, providing shared storage capabilities to virtual servers without the higher costs of SAN implementation.
Simply put, thin provisioning offers a smarter way to allocate storage, reserving what is needed when it's needed, rather than tying up expensive storage. The result will be twofold -- your customers will avoid overbuying storage hardware (which may mean less money spent in the short term on storage), and your customers will appreciate that you educated them on a better way to handle storage allocation, both inside the virtual server environment and outside of it.Barb Goldworm is president and chief analyst of Focus Consulting, a research, analyst and consulting firm focused on systems, software and storage. A frequent columnist, and author of numerous white papers and research studies, she recently released the book Blade Servers and Virtualization: Transforming Enterprise Computing While Cutting Costs, published by Wiley. Barb has been a frequent chair and keynote speaker at industry events on virtualization, blades and storage. Reach her at firstname.lastname@example.org.
This was first published in December 2007