SQL Server 7.0 Clustering

Tip: If the SQL Server 7.0 Cluster Wizard fails before it completes, it can litter the registry of the secondary node with half-completed registry entries, along with leaving various DLLs on the node. If this happens, you are unable to run the SQL Server 7.0 Cluster Wizard again unless the registry entries are first removed, and the various DLLs are cleaned up. This is almost impossible to do manually on your own. Microsoft Support offers a utility called the “SQLCluster 7.0 Remover,” which will do this for you automatically.

Explanation: For whatever reason, the SQL Server 7.0 Cluster Wizard is a frail utility, subject to failure. When it does fail, it doesn’t clean up after itself. What is the worst is that unless the litter is cleaned up, the Wizard won’t run again. This means you must either clean it up yourself (very hard to do, in fact, we tried it and never succeeded), or reinstall the operating system in order to get a clean registry.

One other option is to clean up the registry using a utility called the SQLCluster 7.0 Remover. Unfortunately, this utility is only available from Microsoft Support, and you must call them to get a copy. Essentially, this utility is just a batch file that kills any processes that shouldn’t be running, cleans out the registry, and removes some DLLs. Once it is run, you can then again rerun the SQL Server 7.0 Cluster Wizard.

Version: 7.0

Date Added: 8-14-2001

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Tip: Backing up SQL Server data from a SQL Server cluster should be done with the utmost diligence. Remember, the shared disk array is not clustered, and is in fact a single point of failure.

Explanation: The point of SQL Server clustering is not to protect data, but to ensure that SQL Server hardware and software is running. Should a clustered node’s hardware fail, or a SQL Server instance fail, then SQL Server will automatically failover to the backup node. But if your shared disk array should fail, SQL Server clustering will be of no value.

Even though your shared disk array most likely is redundant (supporting some version of RAID), it is still possible to lose your data. Because of this, making backups is very important.

The most efficient way to make backups from a clustered SQL Server is to perform disk backups, then to sweep the backups from disk to tape for offsite storage. You can either make the disk backups directly to the shared disk array, then move them to tape, or you can make the disk backups to a network share, then move them to tape.

However you decide to do this, consider creating a redundant backup job. For example, your backup job might consist of multiple redundant steps. A first step might be used to perform a disk backup of your databases to the local shared disk array, and a second step might be to move these backup files to another server. But what if the server you are copying the backup files is down, or has ran out of disk space? One option would be to create a third step that only runs if the second step fails, and is used to copy the backup files to another server. This way, should the file copy part of the job fail, then there is logic in the job to try another alternative. This is just a simple example, but I think you can see the potential of this idea.

Version: 7.0, 2000

Date Added: 8-29-2001

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Tip: To prevent the mssqlserver and the sqlserveragent services from being failed over because a less critical service on the server failed, configure the less critical services not to failover the cluster.

Explanation: For example, let’s say you are running the Full-Text Search service on your clustered server. Should it fail, you most likely don’t want your entire cluster (running mssqlserver and sqlserveragent) to failover because of it. Be default, this will happen unless you take explicit steps to prevent this. Of course, you may want the key SQL Server services to fail in this case, but many DBAs don’t want this to happen.

Here’s how to prevent this from happening. Start Cluster Administrator, and then right-click on the non-critical service that you want to prevent from forcing SQL Server to failover, and choose “Properties,” then choose the “Advanced” tab.

On this tab, deselect the “Affect this group” check box, then click OK. You are done. Now, should this service stop, then it will not cause the critical SQL Server services to failover. You will want to do this for each non-critical service that affects SQL Server’s services.

Version: 7.0, 2000:

Date Added: 9-5-2001

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Tip: Turn off any unnecessary operating system services on your clustered SQL Server that you will not be using. This will reduce the cluster’s overhead and speed performance.

Explanation: Not all of the default services that are turned on when Windows NT Server or Windows 2000 is installed are necessary. The same goes true for SQL Server 7.0 and 2000. There are some SQL Server services, such as the Full-Text Search service, that aren’t required for many servers, and shouldn’t be turned on if they are not needed.

If your cluster servers don’t need IIS or any of the other related web services, be sure they are also turned off. I have often found these services have been installed on servers that don’t need them.

The more of these unnecessary services you can turn off, the less overhead your cluster will use, and the better the cluster’s performance. Keep in mind that you need to turn these services off on all servers in the cluster using the Services utility. In most cases, you can get these non-essential services to Manual or Disabled, in order to turn them off. In other cases, you may be able to install them.

Here are some of the services you might want to consider turning off. This is not meant to be a comprehensive list, nor should you turn them off if you should really have a need for them. You will want to test the effects of turning off these services on a non-production server before trying it on a production server.

NetLogin
Browser
Server
Print Spooler
Task Scheduler
License Logging Service
SNMP
Messenger
Version: 7.0, 2000

Date Added: 9-5-2001

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