Stellar Steelhead WAN accelerator reduces network wait time

Riverbed adds Proxy File Service, Microsoft SQL performance enhancement

If you're tired of having your remote users complain about the WAN's performance, it may be time to check out a WAN optimization/acceleration solution. Up until a few years ago, the only way to try to improve poor WAN performance was to throw more bandwidth at it, but that didn't solve the problem -- or make users any happier. The length of the link (latency) is a big factor in performance shortcomings, as is application chattiness and TCP slowdowns when a packet error occurs.

One of the more comprehensive appliances aimed at overcoming the WAN performance problem is Riverbed Technology's latest release, the Steelhead 3010. It's a 3U rack-mount appliance that includes 250GB of disk cache (in RAID), dual redundant power supplies, 10/100/1000 NICs, and an easy-to-navigate Web-based UI.

Now in Version 2.1.2, this latest software release includes new features such as a proxy file service for disconnected access and specific optimization for Microsoft SQL.

True plug and play

Basic installation of the Steelhead solution requires a unit installed at the datacenter and one at each remote office. Setup is as easy as plugging in and connecting each appliance to your network.

As opposed to some WAN optimization appliances, Steelhead requires no special connections or tunnels among boxes; as long as traffic passes through each device, from remote to datacenter, it is automatically classified and optimized. This allows the Steelheads to easily participate in a many-to-many, fully meshed network with redundant and alternate paths.

The last time I had a chance to check out Steelhead, I was blown away by how effective it was at improving poorly performing WAN links and applications. This time, I did another series of performance tests using a Shunra Virtual Enterprise to simulate various WAN circuits and found that last year's test results were no fluke. Steelhead was at its best when the link had high latency and the application was especially chatty, such as during a Windows file copy.

Protocol alphabet soup

Steelhead still focuses on CIFS, MAPI, HTTP, and TCP-based traffic, but now adds specific support for MAPI pre-fetching, MS SQL, and additional optimization for Exchange 2003. Microsoft made some changes to how Outlook 2003 and Exchange 2003 talk to each other, so in addition to the MAPI services already in the product, Riverbed added support specifically for Exchange 2003 to make sure all traffic is optimized. Steelhead will speed up all TCP traffic but does not help out UDP (User Datagram Protocol) traffic.

One feature I really like is the MAPI Transparent Prepopulation. This service will keep open a user's Outlook-to-Exchange connection between the remote Steelhead and the Exchange server, even if the user shuts down his or her PC. With this open connection, it will retrieve any new messages from the user's Exchange mailbox and store them in the Steelhead's cache. When the user next logs on and launches Outlook, the new mail is already staged close to the user and doesn't have to traverse the WAN, which improves response time and reduces load on the WAN.

The Microsoft SQL support allows admins to define the SQL servers for which Steelhead will intercept and optimize traffic. Steelhead can pre-fetch records from the SQL database during a retrieve operation, getting the next set of records and caching them before they are requested. This works with any MS SQL-based application, including MS Project, and really speeds things up.

Choose your mode

One of the Steelhead 3010's best new features is the PFS (Proxy File Service). PFS provides continuous access to files located at the datacenter in the event of WAN failure, so it's invaluable for business continuity.

Of all Steelhead services, PFS takes the most time and planning to set up: The Steelhead appliance has to be a member of the AD (Active Directory) domain, and share paths must be created in Steelhead's management console. I was able to insert my 3010 into AD and create a couple of shares without too much trouble -- but make sure the Steelhead appliance's clock and your domain controller's clock are synchronized to avoid communication problems.

When admins create the shares, they choose between two distinct modes of operation: local and broadcast. Local mode places the authoritative copy of the files on the Steelhead appliance; broadcast mode leaves the authoritative copy on the file server. When the WAN link fails, PFS local shares allow full read/write access, whereas broadcast shares provide only read-only access. When the WAN comes back up, changes made to the PFS local share are synchronized back to the datacenter.

The use of PFS requires that a special application be installed on the file server being proxied. The RCU (Riverbed Copy Utility) synchronizes files between the datacenter and the Steelhead appliance in both PFS modes, and RCU can also be used to pre-populate files into the remote Steelhead cache. It can push out the files either when a change is made to the watched directory or as a scheduled task.

The reporting engine got a substantial makeover in Version 2.1.2 of the Steelhead software as well. The Steelhead 3010 now sports a decent selection of graphical and statistical reports.

One report that I used quite a bit was the Traffic Summary. It provides, at a glance, a pie chart showing overall traffic through the appliance and a line chart displaying each traffic type as a percentage of the overall traffic. Other reports are just as useful and easy to read. IT can apply filters to the reports to view the information in various ways. Unfortunately, there is no way to create and save a customized report.

Just keeps on truckin'

Riverbed's Steelhead 3010 appliance continues to blow me away with its caching and optimization capabilities. The only way to truly appreciate how well it handles long fat links is to get a pair and try them out: With my Shunra Virtual Enterprise, I created some really dirty, nasty WANs; each time, the Steelhead handled the traffic thrown its way.

The graphical reports are a welcome addition, and the Proxy File Service is a good step toward handling disconnected situations. All in all, it's a WAN acceleration winner.

InfoWorld Scorecard
Protocol support (25.0%)
Value (10.0%)
Reliability (15.0%)
Setup (10.0%)
Performance (40.0%)
Overall Score (100%)
Riverbed Steelhead 3010 9.0 9.0 9.0 9.0 9.0 9.0
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