Exam Reviews

Clustering Services

Hardware know-how gets its day in the sun with the Clustering exam. Word of warning: This test isn’t for the faint of heart.

• By Chris Golubski
• 01/01/2001

Well, it’s about time! Microsoft has finally noticed that hardware does play an important role in an enterprise. This test is living proof of that. Not only do you have to know Windows 2000 Advanced Server to pass, you also need more than a passing familiarity with the different types of hardware supported by Microsoft Clustering Services.

True to the format of the Win2K exams, this test has verbose questions and expects you to know the minute details of the product. If you don’t read carefully, you’re liable to select an answer that’s subtly different from the correct one. The test also gives detailed, real-life questions that are enterprise-based. Remember that the Win2K exams are designed for people who have a year or more of experience, so this challenge isn’t for the beginner.

I also recommend being a Compaq ASE or having equivalent training before tackling this one. If you find yourself weak in the hardware arena, this test isn’t for you. You’ll find yourself at a distinct disadvantage if you don’t understand how SCSI, Fibre Channel, and hardware RAID arrays work. Make sure you have a strong background in all of these topics before testing.

Preinstallation Pitfalls
What’s clustering, you ask? Clustering is the process of installing applications on a shared drive or array between two or more machines, called nodes. These nodes are backups for one another in case the other machine fails. If one machine fails, the other immediately takes over for it. This process is called failover. When the original machine is back online and control is returned to it, a process called failback takes place.

Before you can even get out of the gate and install the Clustering Service, you need to know how to configure Win2K Advanced Server. The first thing to understand is what network settings are appropriate. Cluster servers need to be multihomed. In other words, they typically have more than one network card installed. The first network card is used for communication on the public network and the second for communication between nodes on a cluster.

You should know how to configure Win2K Advanced Server to support the multihomed configuration. Be familiar with what protocols need to be installed on which NICs under specific circumstances. Know how to provide fault tolerance when a network card, switch, router, or hub fails. Be able to assess an existing network for utilization problems and know how to improve network communication performance between nodes on a cluster.

Even though this is a test on Clustering Services, knowing the “mundane” network services like DNS and WINS will go a long way. Sometimes problems are as simple as knowing that your particular variety of name resolution isn’t appropriately working. On occasion, a client might not have the correct IP address or subnet mask to communicate with a cluster. Or perhaps a client couldn’t get a lease from a DHCP server, and it configured itself using Automatic Private IP Addressing. All these things are possible problems that could easily happen to clients on a network. True enough, they don’t have a whole lot to do with clustering, but they can certainly affect overall connectivity.

Before you can install the Clustering Service, you need to have physical connectivity to your quorum resource, which—in layperson terms—is your external shared SCSI drive or array. Be able to troubleshoot issues that involve connectivity to Fibre Channel hardware. Know where in your array terminators are placed and whether or not you should enable passive termination of the SCSI chain. Also know what SCSI IDs the quorum resource should have and how the devices should be configured if you have both internal and external SCSI devices.

Tip: I’d recommend getting a good hardware book and learning all about SCSI and Fibre Channel. If you go into the test without understanding the hardware aspect of the exam, you’re going to have a difficult time.

Configuring Clusters
Of course, installation and configuration are the meat and potatoes of any clustering solution. You need to be able to install the Clustering Service on both nodes of a Win2K Advanced Server cluster. It’s important to know how to set up a cluster to work in a domain environment. For example, both nodes of a cluster need to be in the same domain in order to work. It can’t hurt to know what a service account is and what specific rights that service account needs.

Some more basic Win2K understanding on disk configuration can’t hurt either. If you’re already Win2K-certified, I’m sure you know the difference between basic and dynamic disks. Remember, a “stripe set with parity” is what we called software RAID on Windows NT 4.0, but a “RAID 5 volume” is what we call the same thing on a Win2K installation. Consider the fact that nodes have internal hard drives or arrays in addition to the quorum resource. Figuring out which file system and fault-tolerance scheme should be present on internal arrays and external arrays is also a good skill.

In addition to knowing how to install a fresh copy of Win2K Advanced Server and the Clustering Service, be familiar with the upgrade process from NT 4.0 Enterprise Edition to Win2K Advanced Server. Know what issues are associated with the upgrade process and how to resolve anomalies that might occur due to the upgrade.

Tip: Brush up on your Win2K disk-management skills.

Application Awareness
Once the cluster server is installed and configured appropriately, you can take the action of installing your applications. I’m sure you’re thinking, “Oh, this is easy, I can install applications.” Well, it really isn’t as easy as you might think.

First, know if your application is cluster-aware or not. A cluster-aware application is specifically programmed with custom functionality to support clustered installs. After that, you run the application’s installation, but you have to know whether the application gets installed on the quorum device or on the local node’s hard drive. You also have to know where the application’s data files go. It can be a very detailed process.

When installing a cluster-aware application, you need to know what resources the application is dependent upon. Some common examples of resources would be an IP address, a network name, a physical disk, and so forth. Once the cluster server is told what resources an application needs, it’s able to know what to monitor for failure. For example, if a network card fails, the IP address is inaccessible; failover to the secondary node can then take place. You should know what resources are needed and how to add them to an application’s configuration. You should also understand what resources are dependent upon other resources.

It’s a good idea to be familiar with the installation of several Microsoft cluster-aware applications. In Win2K, it’s now possible to cluster several common networking services, like DHCP and WINS. You should know how to set up, configure, and troubleshoot issues that involve these two services. You should also be able to manage a cluster that has IIS installed.

In addition, Distributed File System (Dfs) can be clustered under Win2K—know which type of Dfs (domain-based or standalone) is appropriate under the circumstances. Also, Win2K has the ability to cluster printing services. Be familiar with how to install and configure these items on your cluster server.

Once everything is installed and configured, it’s a perfect world, right? Of course not. The core of our jobs as network administrators and engineers is to be able to troubleshoot any problems that might arise. Know how to start the cluster service from the command line along with all of the associated options. This is usually used to start the services under special conditions when the clustering service won’t start due to a problem.

Tip: Be sure you know where the cluster logs are located and how to manage them.

Management Mayhem
Okay. So now our applications are installed and running like a well-oiled machine. Now what? Well, we have to be able to handle day-to-day management, don’t we? Daily management includes delegating access; handling backups; and being able to handle hardware maintenance, like adding new disks to a cluster.

Be sure you know how to replace a node in case of a total hardware failure. Machines don’t always fail totally, however, so you should be able to replace a failed SCSI disk or RAID array, if needed. Know how to troubleshoot problems that might arise due to a failed quorum resource. Also be familiar with how to remove a node from a cluster and add another.

When a failover occurs, it should be your intent to repair the primary node and return control back to it. If you’re not careful, you can end up attempting to failback before the machine is ready. Know how to configure failover and failback options to avoid this.

Avoiding Accidents
Many things can go wrong during an installation of the Clustering Service. Be able to recover from internal and external disk failures and know how to replace a failed SCSI drive or array. Believe me, if a failure happens, your boss is going to jump on you to fix the problem.

Avoiding disaster is really important, too. Know how to schedule and perform backups of both the data on your quorum resource and your internal drives and arrays. Understand which parts of the Win2K operating system need to be backed up for a successful restoration of a cluster and know how to perform reconfiguration if your backup isn’t complete.

In addition to knowing how to back up and recover, be sure you know how to make the existing system run better. Be able to optimize internal and cluster network traffic to best suit the needs of the organization. Also, understand how to distribute load between clusters, if appropriate, and be able to pick which node in the cluster should be the owner of the application.

Experience is the Key
Like I mentioned, this is certainly not an exam for the faint of heart. I found few study materials for it and no Microsoft Official Curriculum for Win2K clustering. Your best bet (as always) is to have experience with the technologies involved and go from there. Make sure you spend the time to read each question carefully to get all the details. One thing this exam definitely requires is attention to detail. Good luck!