Download the authoritative guide: Enterprise Data Storage 2018: Optimizing Your Storage Infrastructure
Remote storage access is a challenge for any organization with branch offices separated by distance from the corporate data center.
Latency, in particular, is a big issue. The widely used CIFS and NFS protocols, for example, are very chatty, and performance degrades rapidly as latency increases. Try accessing Microsoft Office files over a WAN — it can take an age.
"Office applications involve an enormous amount of handshaking," says Mike Karp, senior analyst at Enterprise Management Associates. "Whenever you open Word, something like 300 transactions take place. Because of all that, you can add as much as 30 seconds to the access time when you remotely try to get into a file at head office."
The traditional approach has been to deploy local storage at each branch. But that adds significantly to total cost of ownership (TCO) in both operating and capital costs.
More recently, a couple of new approaches have begun to gather steam: wide area file services (WAFS) and WAN optimization.
Steve Duplessie, Enterprise Strategy Group
Not surprisingly, the space has been a hot one, with Cisco, Brocade, Juniper, HP and others all making big moves just in the last month or so.
WAFS Speeds File Access
WAFS and WAN optimization are essentially very similar in that they attack delays generated by common protocols. The former addresses file-level protocols such as CIFS and NFS, while the latter focuses on transport protocols.
WAFS solutions speed access to files through a combination of caching and bandwidth optimization techniques. The vast majority of file traffic is absorbed at the edge through caching with normal workloads, and traffic over the wire is optimized through streaming, compression and other factors.
Truls Myklebust, director of product management at Brocade, says WAFS speeds access to files by as much as a factor of 100 for "warm" cache hits (the data is already in the cache at the edge), and 10 to 12 times for "cold" cache hits (the data is not in the cache and needs to be transferred from the core device to the edge device). Beyond speeding access to files in remote offices, WAFS solutions also offload traffic from the file servers in the data center, providing improved performance for users in the data center, Myklebust says.
WAFS allows customers to consolidate all storage at the core, allowing fast access to IT resources and consolidation of infrastructure. WAFS vendors include Cisco — which has acquired both Actona and FineGround in the WAFS space — Juniper, Tacit, XOsoft, Riverbed, DiskSites, Signiant and InMage.
"I've seen Tacit stuff work so fast you literally didn't notice the difference between a local server and one coming in from London," says Duplessie. "The performance gain by doing data de-duplication and compression a la Riverbed is astounding."
With results like that, it's no surprise that the big storage players are gobbling up WAFS startups like turkey on Thanksgiving Day. Brocade, for instance, made a strategic investment — not quite a buyout — of Tacit Networks to jointly deliver a Microsoft Windows 2003-based WAFS platform for branch office file access. Customers purchase a Tacit data center server and remote office appliances that work together to give all connected locations fast access to stored data center files and applications. At the same time, the data center can manage all storage and backup centrally.
Similarly, HP has partnered with Riverbed Technology to bring WAFS to its HP StorageWorks Enterprise File Services (EFS) line. The EFS WAN Accelerator is said to address performance issues affecting WANs by removing repetitive traffic and reducing latency effects, delivering up to a 20-fold increase in effective bandwidth and up to a 100-fold increase in throughput for file, e-mail and Web applications.
Mike Karp, Enterprise Management Associates
WAN Optimization Boosts Network Traffic
WAN optimization (also called WAN acceleration) products speed access to data by inspecting the network packets that go over the wire and optimizing that traffic. This is generally done through a combination of compression (to reduce the amount of data transferred over the wire) and false acknowledgements (to reduce latency).
"WAN accelerators usually use a local appliance and turn the LAN protocol into a long distance protocol that doesn't need all the handshakes," says Karp. "There is enormous value in sending along much terser protocols."
Vendors include Peribit, Expand Networks and Packeteer. Note, however, that products are making their way onto the market that combine both WAN optimization and WAFS, so the lines between them are blurring. Recent acquisitions are also confusing the issue, and WAFS vendors such as Riverbed are adding WAN optimization features to their devices.
"Any time data is moving over a network, it is a good idea to have it optimized," says Duplessie. "WAFS and WAN optimization are not mutually exclusive. They can work together to a common good."
Myklebust, however, claims that WAN optimization does not provide anywhere near the same performance for CIFS and NFS traffic as WAFS. Also, with WAN optimization, he says, all file traffic will ultimately hit the file server in the data center, thus not providing any offloading advantages.
Buy Now or Wait?
Are WAFS and WAN optimization worth buying into now? The big vendors certainly seem to think its time has come. So why is this stuff so hot?
"This technology provides good value," says Karp. "It's cheaper for the likes of Cisco to buy than develop on their own. It's all about getting to market quickly."
From the end user perspective, however, WAFS and WAN optimization may or may not be the next priority. Brocade says that its WAFS solutions are targeted at organizations with remote offices with 10 to 500 or more users using CIFS or NFS, connected with network connections with bandwidth from 128Kbps and up and with latency of 40 or more milliseconds.
"The sweet spot is for typical office environments with commonly used personal computing productivity applications" such as Microsoft Office, says Myklebust. "As a rule of thumb, any customer with remote offices separated by network links with 40+ ms of latency will see great benefits from deploying a WAFS solution."
Duplessie adds that there is significant value in getting local storage and backup responsibilities out of the hands of the branch office.
"Trying to do these functions on site is the worst alternative, the most expensive, the most error-prone, the hardest to do, and is generally a bad idea," he says. "Yet that's how it's done, for the most part."
Duplessie believes the optimum model for IT would be one central hub. If the world could, he says, it would have a single mainframe in one place and everyone else would timeshare into it via terminal servers. WAFS enables you to keep the expertise as close to home as possible, he says.
"Anyone with any remote IT presence should look to get rid of it, including little teeny shops like my own," says Duplessie. "I can't think of any logical reason why anyone would want remote IT anywhere — unless you simply had to."
Karp agrees. He says the deciding factor is the way a company is laid out geographically.
"This technology is ideal for somebody with remote offices that aren't big enough to have their own IT person," says Karp. "It is also handy for companies that send out a steady stream of data to a network of remote offices such as updates to manuals or revisions to operational data."
Whatever you decide, you can bet you haven't heard the last of WAFS and WAN optimization. And as your latency woes grow, the technology may sound more and more appealing.
For more storage features, visit Enterprise Storage Forum Special Reports