In-Depth

From the Trenches: The Case of the Disappearing Printer Shares

What do you do when the standard approach to problem-solving doesn't work?

• By Rob Vazzana
• January 01, 2000

Working in technical support allows you to experience problems across a wide range of products. Inevitably, you find that technical issues are reported on certain products more than others. I've gained an appreciation for those particular problems that involve products I personally don't know much about. The tale I spin here revolves around Microsoft Cluster Server.

The Environment

The phone rang, and I braced for impact. I learned that my customer was having an "unusual problem" with his NT Cluster Server version 1.0 build 224.0. This cluster server has 90 printer shares defined on it and a total of 200 to 250 shares available. The 90 physical printers have HP JetDirect cards in them. This cluster server has been in place for two weeks.

The Problem

The customer has found that when he views the cluster server via UNC name, five or six printer shares mysteriously disappear. No errors are reported, and no trigger event can be identified. Poof! The printer shares just plain disappear. Fortunately, the customer has developed his own workaround: to manually recreate and reconfigure the printer share. Over the two weeks of operation, printer shares have disappeared three or four times. Each time the print shares disappear, the problem involves different printer shares, and none that have previously vanished. When my customer connects to one of the Windows NT servers within the cluster, the printers are still there—the shares just disappear on the cluster server.

The Investigation

You'd think that the printer shares can't grow legs and just walk away. So I began the search to find the cause of their disappearance. I performed the normal steps of reviewing both my local copy of TechNet, and the Microsoft Support Web Site. Neither presented a solution. I even consulted with other Microsoft gurus, and they're all stumped.

After exhausting my available resources, a colleague advised that if he had this call, he would place a call to Microsoft. That sounded like a good plan to me, so I opened my call at Microsoft Technical Support. The technical support representative walked us through verifying that the Cluster Server configuration was correct. For example, we made sure that clients connected to the network name when connecting to the cluster. Also, in checking Cluster Administrator, we noticed that the actual printer resource was disappearing as well as the share point.

It turns out that this was a known issue, internal to Microsoft. The Microsoft Support engineer explained that an internal document was being prepared for publication describing our problem. At the time of this writing, Microsoft has published the article as Q225081, "Cluster Resources Quorum Size Defaults to 64K."

The problem lay within the cluster quorum. The quorum is where the cluster service maintains its current status. If a failover occurs, the receiving node checks the quorum for any updates and the current status. The quorum is also used to designate one of the nodes as the "master" in the event of a network failure, where the cluster service is unable to determine which node is failing. All services would then be failed over to the current owner of the quorum resource.

The key to our problem was our quorum log size. This was set at the default of 64K-somewhat small. This new article indicates that when using the small default quorum value, problems may occur if the number of shares or the transactions increase significantly. For example, the support representative explained that one of the problems you might see is that some of the cluster resources may disappear. Pay dirt! We now understood what was happening to cause our printer shares to disappear.

The Solution

The workaround was to do the following:

1. Enter Cluster Administrator.
2. Right click on the cluster name on the top left.
3. Click Properties | Quorum.
4. Change the log size from 64K to 4,094K (just under 4M).
5. Click the Apply button.

After making these changes and monitoring the server for two weeks, we found no additional printer share resources disappearing. My customer considered the mystery officially solved.

The Lesson

Specifically in regards to Cluster Server, I learned that we should always make sure that our Quorum log size has been increased from the default value!

Generally speaking though, you should expect the unexpected. We can all follow the standard troubleshooting steps in trying to resolve a problem. We can all take the time to ask the right questions and listen closely to our customers. You'd expect that this would lead to a clear problem resolution in most cases. Because of the unexpected though, I still never go to a customer site without my magic-imbued rubber chicken in my work bag.

More importantly, be prepared to call Microsoft for support if nothing else pans out. Fortunately my customer and I were able to get that quick solution we all hope for.