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Leveraging WAN optimization to improve virtual disaster recovery

In part two of this series, learn how WAN optimization can improve virtual DR, and learn how to determine whether or not WAN optimization is right for your company.

Part one of this series looked at how to build a virtualization-ready disaster recovery (DR) strategy with replication and wide-area network (WAN) optimization. Part two of this series looks into how to leverage that WAN optimization to improve virtual disaster recovery. As deployment of and comfort with virtualization rises, companies strive to leverage the mobility and ease of creation of virtual servers to automate and accelerate all aspects of disaster recovery. Snapshots, clones, and on-demand conversions (physical-to-virtual and vice-versa) enable near real-time replication of virtual workloads wherever there is a hypervisor, with availability levels limited only by how often and how quickly workloads and data can be moved between locations.

Clearly, network speed and capacity are the primary factors limiting multi-site DR performance, so cost-effective WAN optimization solutions that deliver more of both on existing networks will be increasingly popular. We fully expect higher demand for WAN optimization as IT managers recognize that it provides dramatically higher levels of replication and, in turn, overall data center availability.


WAN optimization for disaster recovery
Who should explore WAN optimization?
What does WAN optimization deliver?
Benefits of WAN optimization
How to evaluate WAN optimization solutions for disaster recovery

WAN optimization for disaster recovery

Enterprises should be investigating solutions to optimize network capacity and utilization today, to ensure that WAN bandwidth and latency are not limiting factors in current or future DR planning. Unlocking existing -- but untapped -- WAN bandwidth early in any DR planning effort will help avoid overspending on other DR solution components (storage or tape stackers, for instance) in the future.

Who should explore WAN optimization?

WAN optimization immediately breaks down operational barriers, relieves geographic limitations, and opens opportunities to leverage emerging storage technologies. You should explore WAN optimization (see sidebar "What does WAN optimization deliver") if any of the follow statements are true:

"I can't reliably meet my DR service-level agreements (SLAs)."
If you only replicate a subset of critical data or workloads within data centers and on
local area networks (LANs), and rely on tape backups or portable disks for disaster recovery operations between sites, your ability to predict recovery time objectives (RTOs) and/or deliver adequate recovery point objectives (RPOs) will vary and be difficult to test. WAN optimization can deliver near-LAN performance over WAN links, enabling more site-to-site data replication for tighter RPO/RTO SLAs. Also, with automated network Quality of Service (QoS) management, WAN optimization allows you to test your DR processes more often and test them on live networks without affecting application traffic.

"It's difficult to protect multiple, geographically dispersed locations."
WAN optimization allows you to overcome the bandwidth mismatch between your LAN and WAN environment, enabling you to back up more often and to more locations: data center-to-data center, branch-office-to-data center, remote-worker-to-data center etc. By overcoming protocol latency, WAN optimization allows you to transfer backup and recovery data sets over greater distances without performance degradation. Also, WAN optimization allows you to continuously replicate or move sensitive data held in multiple locations to a single secure location for improved compliance auditing.

"I want to centralize my backup operations to reduce redundancy."
WAN optimization can eliminate local tape backups and the staff required to manage them. Centralizing data protection leverages the data center staff and skills you have in place today and reduces dependencies on branch office contractors and other third-parties. WAN optimization benefits every data center discipline: the storage team can deploy advanced, bandwidth-hungry data replication technologies between sites and arrays; the server team can take VM snapshots more frequently and back them up to multiple locations; and the network team can deliver higher performance returns for every dollar spent on WAN capacity.

What does WAN optimization deliver?

Disaster recovery objective

Solution capability

Increase WAN utilization and efficiency

Lowers network inefficiencies via TCP optimization, allowing maximum use of rated capacity for existing networks and enabling more DR data sets to be sent more often.

Overcome application protocol latencies

Overcomes inherent application protocol latencies to allow backup/replication to multiple data centers and remote sites at greater distances.

Reduce data on the wire

Lowers the amount of duplicate data sent over the WAN to shorten both backup and recovery times and enable near-synchronous replication.

Optimize performance for DR workloads

Automatically detects and tunes network performance for bursty traffic and large datasets, providing additional optimization specifically for DR.

Manage contention

Brokers contention for shared WAN resources to maintain required throughput for application workloads during DR operations or test runs.

Benefits of WAN optimization

WAN optimization extracts more from your existing WAN links, increasing the immediate ROI for your current network and helping you delay or avoid purchasing additional capacity. The operational benefits for DR are as follows:

Greater flexibility: More data backup and replication to more sites, in more configurations (1:1, 1:N, N:1, physical-to-virtual, virtual-to-physical, mobile-to-data center, etc.) allows for maximum flexibility and agility.

Higher cost efficiency: Unlocking additional capacity on existing networks extracts value from what you already own, and helps delay the need to purchase additional capacity.

Lower data risk: Consolidated protection reduces complexity, redundancy, and potential for data loss; and fewer locations where sensitive data resides leads to simpler and more successful compliance audits, lowering the overall data risk in your environment.

Higher availability: Protecting more workload types and data repositories to multiple locations and taking advantage of more replication raises your overall enterprise infrastructure availability levels.

Shorter RPO: Replicating more often and protecting service quality for other network traffic ensures that the most current data possible is available as close as possible to where it needs to be.

Shorter RTO: Overcoming protocol inefficiencies and reducing data on the wire allows fast transfer of backup datasets as well as more frequent replication.

How to evaluate WAN optimization solutions for disaster recovery

How should you identify the best WAN optimization solution for your chosen data backup and replication technologies? First, explore the relationship between all vendors: confirm that they have tested the joint solution fully, certified and documented it to both vendors' standards, and provide published benchmarks. Once this baseline is established, look for these technology differentiators:

TCP optimization: The solution should maximize the amount of data per payload on each TCP round-trip, remove redundant WAN data and offer high-speed TCP options (HS-TCP, MX-TCP) to fill the network "pipe" most effectively. Leading solutions deliver 60% to 95% reduction in WAN utilization.

Data optimization: The solution should employ advanced data deduplication algorithms and optimize the use of on-board processing power and memory. Deduplication should be at the byte level, and produce data reduction ratios that exceed and enhance block-based data differencing technologies provided by storage vendors. Data reduction ratios should range from at least 4:1 to 8:1 or greater.

Workload optimization: The solution should provide disaster recovery-specific workload identification and acceleration; automatically detect DR-specific traffic (requests for large datasets, for example), intercept requests and segment the data for maximum wire efficiency using adaptive algorithms. Optimization should yield at least five times, and up to 50 times improvement in WAN-based backup and recovery times.

Quality of Service (QoS) management: The solution should broker contention for and allocate WAN bandwidth by application and/or port, while independently prioritizing packets based on individual latency sensitivity for both TCP and UDP traffic. Leading solutions provide innovative QoS tuning algorithms that allocate the minimum bandwidth required for each application, avoiding overcompensation.

Transparency and availability: The solution should be essentially transparent to your existing network infrastructure from various vantage points (user, deployment, reporting, port- and address-level); it should enable centralized management of multiple systems; and it should offer advanced availability, scalability and deployment features, such as efficient use of on-board memory, solid-state drives (SSDs) for caching and clustered configurations.

Overall, a new approach to disaster recovery is required, and this approach should be one that addresses the key constraint on enterprise DR scalability and efficiency: limited network capacity. WAN optimization removes this "choke point" by unlocking existing network bandwidth and optimizing the WAN for the unique transport requirements of backup and recovery workloads. The proven benefits of WAN optimization include dramatic data reduction ratios and massive gains in network throughput, and these benefits are even further magnified when combined with data storage replication solutions from the premier array vendors.

This powerful joint solution makes long-distance, multi-site data replication feasible, simpler, cost-effective, and also provides the clearest path to reducing enterprise dependence on expensive and error-prone tape-based disaster recovery.

About this author: Dave Bartoletti is a senior analyst and consultant at the Taneja Group. Bartoletti has developed, delivered and marketed emerging technologies for more than 20 years at several high-profile infrastructure software and solutions companies. He was at the forefront of the virtualization, data center automation, messaging middleware and Web 2.0 technology waves as both a vendor and consumer. Bartoletti advises Taneja Group clients on server and storage virtualization technologies, cloud computing strategies and the automation of highly virtualized environments. He also has a deep knowledge of the unique requirements of the global financial services industry.

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