Launched late last year and priced from £12,480 (ex. VAT), Zeus ZXTM 4.1 is an enterprise-class load balancing system suitable for virtually all TCP/IP-based applications. Most companies buy ZXTM to help with web-based applications, but the appliance also comes with support for SMTP, POP, IMAP, DNS, LDAP, FTP and telnet. In fact, ZXTM is a proxy server that can sit in front of a set of TCP/IP services, and other protocols and applications can be handled using the ZXTM’s scripting capabilities.
The suite is available in several formats. It can be purchased as software to run on Linux, Solaris and FreeBSD servers. It can also be purchased as an appliance, and Zeus offers several versions with the high-end device featuring 4GB RAM and five network interface cards (NICs). More recently, Zeus has also begun offering ZXTM as a virtual appliance; this is a virtual machine (VM) containing the suite already installed and configured to run in a Linux environment. Although the VM does not match the performance of the suite running on dedicated hardware, it can be installed and running in about three minutes, and can be backed-up and managed alongside other VMs.
Although ZXTM runs on a Linux operating system, companies don’t necessarily need to employ a Linux expert in order to use it. The suite is configured from a slick, graphical browser-based management interface that can be accessed from any suitable PC. You don't even need a spare server or Linux expertise to evaluate ZXTM because an evaluation VM version is available that can be installed on a desktop PC or notebook running the free VMware Player software.
Despite all the advantages of running server software in the virtual machine format, network I/O is a little less efficient with VMs than on dedicated hardware, so most people would install ZXTM onto real server hardware if they decided to proceed with purchasing the suite after evaluation. Two servers running ZXTM could be configured to work in a cluster to provide a fault-tolerant load-balancing system.
Virtual evaluation
We used the VM evaluation version of ZXTM for this review, which is available on a CD-ROM or by downloading it from Zeus. The VM comes in a TAR-format compressed file archive. We used WinZIP to extract this file to a directory on a desktop PC running VMware Workstation. With a few simple mouse clicks in VMware Workstation we had the ZXTM eval system running properly.
ZXTM comes as software, a hardware appliance and a virtual appliance ready-configured for a Linux environment. This is the main screen for the virtual machine running under VMware Workstation.
The main screen on the evaluation VM shows the IP address, username and password needed to connect to the ZXTM. We were impressed by the ease with which we could install the evaluation version and work through some example scenarios, such as setting up simple web server load balancing. Some sample web sites are included with the VM to make it easy to test the example scenarios without interfering with real applications.
The suite also includes tools to save the current configuration to a backup file, and this facility is used in the evaluation system to provide a quick way to restore the appliance to its original state after experimenting with some of the test scenarios.
We used the browser-based management interface to set up simple load balancing for two web servers. ZXTM comes with seven wizards to simplify common management operations such as removing and draining nodes, joining a cluster and handling SSL-based applications.
We used the 'Manage a new service' wizard to set up load balancing for our web servers. The wizard presents four dialogue boxes (see the 'Images' tab, above), one of which asks which IETF protocol and TCP port are to be used, while another asks for the hostnames of the web servers that are to be load balanced. It took about one minute to configure load balancing for two web servers using the wizard.
In addition to load balancing various services, ZXTM is also able to rewrite requests as they pass through the appliance. This capability can be used to redirect requests to specific servers. This is sometimes necessary, for example, when a web site has been redesigned and content moved to a new location, because links to the old location may still be used in old documentation. Requests are rewritten by ZXTM according to rules associated with each service. These rules can either be created using a graphical wizard-like tool, or can be entered using ZXTM’s built-in scripting language, called TrafficScript.
ZXTM can rewrite requests as they pass through the appliance. Requests are written according to rules associated with each load-balanced service.
We used the RuleBuilder interface to create a rule that rewrite requests to http://webserver/products/ so they actually go to http://webserver/services.html. Again we were impressed by how quickly we could set up such rules — this one took less than a minute to add to the system. We were also impressed by the range of options available in the RuleBuilder interface to handle HTTP applications. However, there is nothing there to help with other applications and protocols, so these would need to be handled using the TrafficScript programming language. Fortunately there's a button in the RuleBuilder interface to convert a rule into TrafficScript, so it’s relatively easy to learn TrafficScript by experimenting with RuleBuilder.
A button in the RuleBuilder interface lets you convert a rule into ZXTM's built-in scripting language, TrafficScript.
However, with its ability to rewrite content, monitor service levels and handle multiple protocols, ZXTM is an extremely powerful suite, and better support for protocols other than HTTP would be welcomed by organisations that need load balancing or advanced routing capabilities for non-TCP/IP applications.
Service & support
Zeus Technology has a range of support packages, from Evaluator up to Enterprise level, offering some combination of email access, telephone access, priority response, 24x7 support, software subscription, named contacts and Advanced Replacement Services (ARP). Zeus's web site also hosts a ZXTM KnowledgeHub where customers can share their experiences.
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