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Scale-out iSCSI SANs as a Force Multiplier for Virtualization

John Spiers

With the remarkable growth of storage in data centers and remote offices, efficient block storage management and economic access to enterprise information has become both more important and more difficult to achieve. Enterprise storage is often doubling each year as the volume of business critical information continues to increase.

Server virtualization further complicates storage requirements, leading to headaches for IT departments trying to manage and stay on top of their storage needs.

Scale-out iSCSI (Internet Small Computer System Interface) SANs offer datacenter managers the most cost-effective way of coping with these rapidly growing storage requirements. These SANs are typically based on a collection of standard, inexpensive computing and storage components bound by specialized software into a distributed system. Often referred to as virtual storage, in aggregate these components offer unprecedented flexibility, enhanced reliability, and reduced total cost of ownership and systems management overhead.

Using iSCSI SANs that are based on a scale-out architecture, administrators can build a virtual storage environment and manage a pool of storage instead of individual storage devices. Simply adding storage systems to the cluster when additional storage is required can easily expand this pool. Logical storage volumes can be divided up and the blocks distributed across the cluster of storage systems. These volumes can also be moved around as necessary, depending on how often the data is accessed.

A scale-out architecture approach also reduces costs and mitigates performance issues by automatically balancing data volumes across all disk drives, network connections and processors with each node added.

In a virtualized environment, scale-out iSCSI SANs remove distance limitations and allow physically dispersed systems located around the world to appear as a single logical network. When properly configured, iSCSI SANs can be available to any authorized user at any location in the world with an Ethernet connection.

Availability is also a pressing concern. Virtualization makes the need for both high availability and disaster recovery a reality for companies of all sizes. Traditional storage can limit implementations and make it harder to recover from a site failure or disaster. Scale-out iSCSI SANs offer simple high availability solutions for virtual server environments with automated failover after a disaster, or something as common as a power or network failure.

Scale-out iSCSI SANs create virtual, redundant volumes that span multiple sites. This means that servers see the same volumes, and connect to the volumes through an IP address. This makes failing over servers and virtual machines a simple process. A site failure is detected within seconds and the virtual machines start up within minutes at the remote site-as opposed to the several hours that are typically required for an administrator to physically go to the site and bring the servers online and connect the VMs to a different SAN with distinct volume copies.

With scale-out iSCSI SANs, users can change storage configurations as often as changes are made at the application layer. There is no need to hire a specialist to handle the task. Users can easily manage remote offices or a lights-out data center from one centralized location, scaling performance and capacity without taking applications offline.

The benefits of scale-out iSCSI SANs are significant:

  • Available at a fraction of the cost of most traditional SAN offerings for both implementation and operational costs. Affordable SANs help remove the cost barrier of classic SAN architectures and the economic barrier to the adoption of virtualization.
  • Remove the limitations of individual physical devices and the daily management of physical assets.
  • Work within budget constraints by allowing storage purchases only when needed, not months or years in advance. This allows the addition of capacity and performance with each storage purchase, making the most of storage investments.
  • Can be realized in a remote office or branch of an enterprise, or a smaller business, where the greatest growth in storage is occurring and economy is the watchword.
  • Provide built-in high availability and disaster recovery features that enhance server virtualization capabilities to deliver better business continuity.
  • Provide management simplicity, enabling server and storage administrators to manage the SAN and make the most of limited administrator resources and without requiring specialists. By removing complexity from the environment, IT staffers are better able to meet the needs of the business and the users. This also allows the business to operate continuously and without disruption.

With the right storage solutions, IT organizations can truly unleash the power of virtualization across the infrastructure to mitigate risk and increase business productivity.

*A scale-out architecture provides more processing power by clustering or otherwise splitting up the workload over many different servers, so each individual server need only be powerful enough to handle the load of a smaller percentage of the overall systems. This architecture offers the benefit of running multiple systems on multiple servers, with one or two failover or standby nodes available to take over in the event that one server dies. In this way, a scale-out architecture takes care of local high-availability concerns.

About the Author
John Spiers is the Chief Evangelist for LeftHand Networks, an HP company.

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