Think Storage When Virtualizing Servers

fact sheet Vendor: Hewlett-Packard (www.hp.com) Vendor's Information: About HP LeftHand P4000 SAN Solutions About Hewlett-Packard vendor resources Rethinking Business Continuity Server virtualization software has brought great relief to IT organizations searching for high availability (HA) and disaster recovery (DR) solutions with a low cost of entry. But the same organizations that choose server virtualization as part of their HA and DR strategy often overlook the requirement for a shared storage solution that adequately supports the HA and DR features their server virtualization solution offers. The Secret to Successful Virtualization As companies large and small have learned the hard way, you can negate the cost-saving benefits of server virtualization by choosing an inefficient SAN storage solution that does not properly support the advanced requirements of virtualized environments. Special Report: What You Need to Know Now About Storage and Virtualization No matter the size of your organization youll find food for thought in this special report on storage for your virtual server infrastructure and data center transformation through advanced storage virtualization. Youll gain valuable insights into ways to build a master plan for your infrastructure that makes the most of your virtualization investments.

Data centers can benefit from server virtualization in a number of ways, which is why virtualization is one of the most popular technologies of the decade. Server virtualization helps organizations save money by increasing server utilization rates, increasing availability, helping control power and cooling costs, and making businesses more flexible.

Server consolidation is the most popular reason that IT managers turn to virtualization in their data centers, but there are other applications for server virtualization, including high-availability and disaster recovery, that businesses can use to maximize their investment if they handle the associated storage requirements correctly.

Rethinking Server Virtualization It is all too easy to spend the savings from server virtualization on inefficient storage systems. Because they overcome many of the cost and management limitations of traditional SANs, iSCSI SANs are becoming the preferred choice to support virtualized environments.

High availability and disaster recovery applications require external shared storage with a comprehensive feature set to support them. It's important that IT managers choose their storage wisely because the wrong decision will erase any of the cost savings they were experiencing with server virtualization. Storage systems can quickly drive up the cost of virtualization projects. Traditional storage area networks (SANs) suffer from cost and management limitations.

One of the issues with external shared storage is that it can be very inefficient because it often requires the purchasing of more storage up front. For example, a 100GB volume that is only half full still requires 100GB of storage—even though its full capacity may not be used for years. The problem of excess capacity becomes even more evident when temporary volumes to support test and development environments still consume 100GB—although they will never be filled and will only be needed for days or, at most, weeks during testing.

In today's economic environment, it is difficult to budget for future storage needs, but the deployment model for traditional SANs calls for purchasing a storage system with headroom for future expansion. The budgets for small and medium-sized businesses (SMBs) often dictate the purchase of a low-cost SAN solution. But low-cost SANs often lack the features required to support synchronous replication for high availability, asynchronous replication for disaster recovery, and enterprise-class storage management features. Even when these features are available, they are often costly add-on components that drive up the cost.

How Storage Costs Add Up
Several different types of applications can drive up storage costs, especially in a virtualized environment.

When it comes to backups, more virtual machines mean more logical volumes—and that means more snapshots for backups. A traditional SAN requires a 100 percent reserve, meaning that the same half-full 100GB volume requires an additional 100GB for each snapshot.

High availability applications require an additional storage system and additional synchronous replication software to keep data continuously available in the event of a single SAN failure. This is not only expensive; it is also complex.

Disaster recovery using remote replication can drive up storage costs. Many storage replication solutions require multiple copies of data and massive capacity reserves that can increase storage inefficiency by a factor of three or more

HP LeftHand P4000 SAN Solutions are iSCSI storage networks based on storage clustering—a form of scale-out storage that creates a scalable storage pool by aggregating the critical components of a number of storage systems into a single pool of resources, or storage cluster. The cluster accepts and responds to iSCSI requests as a single system.

In an HP P4000 SAN all physical capacity is aggregated and is available to the volumes created on the SAN. When more storage is needed, users can add additional storage systems to the cluster; the cluster seamlessly, non-disruptively reorganizes its storage to incorporate the new system into the cluster. This approach enables new levels of availability in HP LeftHand SANs, and cuts storage costs in half. HP LeftHand SANs also feature built-in support for high availability and disaster recovery implementations, scalable performance, and straightforward management.

Thin provisioning is a built-in feature that underlies every P4000 SAN. The storage cluster manages all of the storage allocation underneath a logical volume; thin provisioning allocates space only as data is actually written to the volume. This provisioning allows users to purchase only the storage they need today, adding more as application data grows.

Storage clustering combined with thin provisioning in HP LeftHand P4000 SANs improve overall storage efficiency and increase ROI by increasing capacity utilization. HP LeftHand SANs get 33 percent better utilization than traditional storage arrays in a single site configuration, and twice the capacity utilization in a multi-site high availability configuration.

Consider how storage clustering and thin provisioning combine to reduce the cost of storage as it increases the cost-effectiveness of storage virtualization. HP LeftHand P4000 SANs allocate disk blocks only as they are needed, which means thin provisioning uses storage more efficiently. For example, a 100GB storage volume that is half full uses only 50GB of storage, allowing you to defer storage purchases until more disk space is actually needed.

Snapshots in an HP LeftHand SAN are space-efficient because they are also thin provisioned. A snapshot of a 100GB storage volume requires no reserve; it allocates space only as the contents of the primary volume and the snapshot diverge.

With HP LeftHand SANs, multi-site high availability can be implemented at no additional cost. Simply split a storage cluster between sites, and built-in synchronous replication handles block replication, failover, and failback automatically. The volumes are continuously available and ready to support failover of virtual machines—even in the event of dual disk drive failures, storage system failures, rack and power failures, and site disasters. This configuration doubles capacity utilization and provides applications with new levels of availability.

Disaster-recovery solutions with HP LeftHand SANs now require only two copies of a volume's data. First, a space-efficient snapshot of the volume's data requires no space reserve. Second, the remote copy can be used at the remote site without creating an additional copy for mounting .Using the example of a half-full 100GB volume, a traditional SAN requires 300GB of storage, while the P4000 SAN solution requires only 50GB—a six-fold improvement.

HP LeftHand P4000 SANs make copying existing volumes—or "golden master" images—as easy and cost-effective as creating the new virtual machines that use them. HP SAN/iQ® Software with SmartClone Technology makes space-efficient volume copies that allocate space only as the volume contents are changed by the virtual machine using them.

The dynamic nature of virtualized environments creates havoc with most storage systems. While it is easy to create, copy, move, or delete virtual machines, doing the same with logical volumes is antithetical to their "configure once, leave alone" design. Because P4000 SANs are based on standard servers and IP networks, virtually everyone has the skills to install and support a P4000 SAN, and virtually every data center has the equipment to connect SANs with servers.