SaaS-based load balancing

Tzolkin’s TZO-GEO load balancing service

Web Applications Alert By Mark Gibbs, Network World
March 17, 2008 08:56 AM ET

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Way back in the mists of Internet time (5 years ago) I wrote about a service from Tzolkin called AutoFailover.

AutoFailover provides Web Applications with an outsourcers, Software-as-a-Service (SaaS) style mechanism for handing over service from one server or groups of servers to another. This piece of genius works by assigning Tzolkin's DNS servers as the authoritative DNS service, and then monitoring the servers. When a host fails to respond, the DNS servers dynamically reassign DNS resolution within, at most, 2 1/2 minutes.

Along with this service came Tzolkin's load balancing service called TZO-HA (that’s HA for "high availability"), which provides an intelligent round-robin rotation scheme for a group of nodes (AKA servers).

Tzolkin has taken this latter service a step further with its geographic load balancing service called TZO-GEO. What is so interesting about this product is that it costs roughly one tenth of the cost of comparable load hardware-based balancing solutions such as F5.

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Compared with hardware solutions, there is a downside: All of the other features that come with hardware solutions, such as SSL acceleration, are absent.

That said, here’s the interesting thing – in these times of shrinking budgets finding the money for serious capital expenditures can be, to say the least, pretty tough. A hardware-based load balancing solution could come in at around $300,000 for three sites while with TZO-GEO the cost would be around $30,000 per annum!

The way TZO-GEO works is that when client requests are received at any of Tzolkin’s five DNS clusters in the U.S. or its other cluster in London (a Singapore cluster is planned to go live late this year), they are mapped to geographic locations and the TZO-GEO service returns a response that directs the client to the “nearest” server.

Obviously the improved response time is dependent on many factors, but is usually considerably better than the unload balanced service. Moreover, the service is adaptive – it is possible to weight some members of the geographically balanced group higher or lower than others and even have that weighting redefined automatically when a server reaches a stress threshold.

The Tzolkin services have a very slick combined control panel so you can check on the status of any mix of services as applied to your servers.

The Tzolkin DNS servers are proprietary Linux implementations originally designed for gaming support so robustness and performance were key design goals, which meshes very neatly with the needs of Web applications providers. Tzolkin also provides both uptime and service-level guarantees.

The fact that all that is required to make the TZO-GEO work with any group of servers is to make Tzolkin’s DNS servers authoritative is a powerful inducement for resource-strapped organizations. And as I pointed out, the pricing helps: AutoFailover is still priced the same as when I wrote about the service in 1993 ($149 per month for two nodes), while the standard failover service is priced at $174 per month, and the geographic failover service is $399 per month for the first node with discounts for subsequent nodes. Additionally, to those prices are charges for DNS queries per month beyond a base level of 750,000 queries.

Mark Gibbs is a consultant, author, journalist, columnist and blogger.