Software makes NT 4.0 servers redundant
- By Kevin J. Brady
- Dec 20, 1998
The new version of Vinca Corp.'s Co-Standby Server for Windows NT offers an efficient and reliable way to provide fault tolerance for critical resources in a Microsoft Corp.'s Windows NT 4.0 environment. Vinca's product lets agencies create two-server clusters, where a mirror copy is created of the data on one or both servers. Should one server fail, the other kicks in so there is no downtime for users.
The cluster setup requires two Windows NT 4.0 servers with Service Pack 3 or later and 30M of free disk space on the system drive for the server files. The servers can be domain controllers or member servers but not one of each, and both servers should be in the same domain. If each server is a mirror for the other— a so-called active/active environment— three hard disks are needed. If just one server is a mirror for the other— an active/passive environment— two hard disks are required. Any standard network driver interface card that uses Microsoft's Network Driver Interface Specification can be used.
The Co-Standby Server uses Redundant Array of Independent Disks Level 1 to provide its redundancy and set up failover groups. In the active/active mode, each server provides a drive for the cluster so that the resources exist on both drives. In the active/passive mode, the main server is active on the client network and the other exists to provide backup.
To test redundancy features, we installed the software on a Windows NT 4.0 Primary Domain Controller and Backup Domain Controller. After the two systems were clustered, the PDC was turned off. The failover worked flawlessly: The resources from the PDC were still available, and the Management Console indicated that the failover had taken place.
When configuring the cluster, you have two choices. You can have the mirrored data use the client network to replicate to the other server or you can set up a dedicated Internet Protocol link between the two servers. Vinca recommends a dedicated link, and the software comes with a crossover cable to aid in its setup.
Installation of the package's two components, the Standby Server and the Management Console, is easy and quick. It took four minutes to install the server and about three minutes to set up the console, which can be installed on the servers or a separate workstation. The install portion of the manual is well-illustrated, but you may not need that section because the few setup screens involved in installation are intuitive.
Once the cluster is set up, install the Management Console, which is an excellent, highly intuitive utility used to cluster resources and check on the status of your cluster. It provides three windows: one for each of the resources on the servers and one for the entire cluster. Through the cluster window you can cluster volumes, shares, IP addresses, printers and applications. Two clearly marked link status indicators— green or red— show if the network link and dedicated Vinca links are running.
Once an item has been clustered, it is displayed with a colored diamond next to the normal resource icon. If a resource cannot be clustered, such as the system disk, it is shown with an interdiction sign.
As part of our test, we brought up the Management Console, then created a shared printer on the other server. Returning to the console, we told it to scan for resources. The printer showed up in a few seconds, and we were able to cluster it without any difficulty.
With clustered applications, script files can be implemented to start the application on the failover server. Application support scripts are available from Vinca for Microsoft SQL and Exchange. Vinca also develops scripts for other applications and makes them available on its World Wide Web site.
The manual is comprehensive, well-written and richly illustrated with screen shots of all the important operations. It is more than a how-to-install manual; it provides in-depth explanations of how the product works in conjunction with Windows NT. In addition, the install CD-ROM also provides an important readme file, which you should print out and read before installing and configuring.
Current users of Vinca's Co-Standby Server for Windows NT include the Energy Department, the Federal Communications Commission and the National Institutes of Health.
-- Brady is a computer systems instructor based in the Washington, D.C., metropolitan area.
Report CardCo-Standby Server for Windows NTVinca Corp.(800) 934-9530www.vinca.com
Price and Availability: A server pair is priced at $3,121 on Government Technology Services Inc.'s GSA schedule. For more information, call (800) 999-4874. A 30-day free trial is available form the Vinca World Wide Web site.
Remarks: The Co-Standby Server is an excellent clustering solution that provides redundancy for a variety of resources on your Windows NT 4.0 servers.
Final Score: Excellent