Data centre managers know that having multiple copies of files and applications spread out across an organisation is inefficient and expensive at best and can be downright risky at worst, exposing the enterprise to potential legal, security and compliance issues. Also, maintenance and service costs to run local servers and file storage can be tens of thousands of pounds per branch office - money that could be redeployed if consolidation could be achieved.
Driven by cost, security and compliance issues, some managers have tried to centralise applications and files as part of a data centre consolidation programme. The problem is that if you transfer everything to a central pool, people trying to access applications and files from a distance very soon encounter difficulties. Most applications are designed to work over a Local Area Network (LAN), where bandwidth and latency are not an issue.
Many of these applications like to "talk", otherwise known as being "chatty", making perhaps tens or even hundreds of calls to render a single page or transfer a file. This is fine if they are communicating with a server down the corridor and the latency or end to end delay is small because the distance is short.
But over many miles, and over a connection that only has limited bandwidth to spare, the impact of all this traffic starts to tell. A medium-sized file, of a couple of Megabytes, can take half a minute or more to open over a Wide Area Network (WAN) connection. This often cannot be fixed purely by increasing bandwidth.
If you are sat in a branch office, facing an angry customer or a high-value prospect, this simply is not good enough. If you need to access an Oracle, Siebel, SAP, Citrix or HTTP application, or get a file to review, you need it now, without delay.
It is not surprising, then, that branch operations may prefer to ignore the inefficiency, cost and risk and opt to either keep their files and applications close to them, locally, or avoid using them at all.
Unless, that is, data centre managers can find a way of overcoming the limitations of remote access over a WAN. Traditionally, the answer has been to throw money or, more specifically, bandwidth, at the problem.
Increasing the bandwidth of WAN links can certainly help where the amount of data is the bottleneck, but the cost is usually very significant and only useful if bandwidth capacity alone is the issue. This cost can largely outweigh the benefits of consolidating everything in the first place and still may not fully solve the problem as latency can be the killer problem.
A smarter answer to the problem is to use some method of accelerating the application's traffic across the WAN. One approach is to create an overlay network which controls and optimises the direction of application packet flows.
The problem with this Wide Area Optimisation (WAO) technique is that it not only creates another network that you have to worry about, but it can also interfere with the existing network's ability to choose the fastest paths for all traffic flowing between nodes.
This can effectively dumb the network down and affect productivity and speed, particularly in networks that use asymmetric routing techniques. And if you have voice over IP, the quality of service (QoS) parameters that prevent latency will be harder to enforce as there will be conflicting calls for the network bandwidth.
Also, WAO techniques may use tunnelling, using accelerators to aggregate flows for all the communicating nodes into logical tunnels.
However, these accelerators create proxies that will obscure vital packet header information, such as IP addresses and TCP port information. This then affects network services, such as QoS, firewall policies, NetFlow caching and Network Based Application Recognition protocol discovery and classification, that rely on intermediary devices.
Furthermore, if an accelerator tunnel connection fails then it can be necessary to reset every connection within the tunnel, which will impact network resilience.
Ideally what is needed is a way of accelerating traffic that has the following characteristics:
? A complete transparent integration, both logically and physically, with the existing network, requiring no changes to clients or servers.
? Content distribution, caching and data compression for reducing WAN traffic loads and WAN congestion.
? Application adapters that function as application-specific protocol proxies in the branch to reduce application-specific latency.
? Transport flow optimisations that increase throughput without manipulating information that is vital for enabling value-added services hosted within network infrastructure.
? Performance-monitoring capabilities and QoS functions for application recognition and traffic prioritisation so voice and data traffic are delivered with the correct QoS.
Such platforms now exist. And they have a significant impact on an organisation's ability to deliver applications over a WAN.
Tests conducted on one of these Wide Area Application Services (WAAS) platforms by Veritest, an IT benchmarking firm, have demonstrated that traffic over the WAN can be cut by over 85 per cent. This can lead to bandwidth savings, and significant response time improvement for applications,
In one trial, a 2MB Microsoft Excel spreadsheet that took 32.2 seconds to open over a standard T1/E1 WAN connection with a 100ms delay was opened in just 1.7 seconds using WAAS. Typically, using WAAS improved performance for file users by between around 70 and 90 per cent reducing delay /response times and improving user satisfaction.
In another test, though, a 2MB Microsoft Word file opened 14 seconds more quickly with WAAS, representing a 600 per cent improvement.
Veritest concluded that organisations adopting WAAS technology could benefit in a number of ways, including:
? Improved speed for file access and sharing, through latency reduction, operation batching, read-ahead and advanced caching technologies.
? Enhanced data protection, by allowing master copies of all files generated from a branch to be stored centrally in a data centre where they could be more easily protected and managed.
? Lower total cost of ownership, through optimisations that negate the need for costly file/print servers and data protection infrastructure in branches.
? Reduced administration, by allowing IT administrators to centrally manage files services and policies, including use quotas, backups, disaster recovery, restores, access control and security policies.
Meanwhile another testing company, Miercom, reported that when a 170MB binary file was dragged and dropped from a simulated data centre's desktop folder to a branch office folder, the operation took just 25 seconds when supported by WAAS technology. These radical improvements render the centralisation almost invisible to the user.
With results like these, it is clear that data centre managers can now have their cake and eat it. Hosting applications and file storage centrally need no longer be feared, and is unlikely now to result in any significant degradation in the branch office performance, given that the planned approach has integrated WAAS technology in the network architecture
This new approach to IT consolidation will of course, result in major benefits for the business in cost, compliance and security.
In this particular tug of war, the argument for keeping applications and files in the branch has just got rather ropey.
Tags: Networks & Telco