Vinca StandbyServer for NT

How would you like a software-based fault-tolerant clustering solution that is easy to set up and use and will work on almost any server (including servers you might already own)? Vinca StandbyServer for NT uses Windows NT's disk mirroring capabilities to mirror a hard disk partition on your primary server to your backup server over a high-speed link. If your primary server fails, the backup server takes over, using the mirrored data until you fix the problem with the primary system and bring it back online.

To run StandbyServer, you need two servers with similar capabilities, two Intel Pro100/B Ethernet controllers, and a free hard disk partition on the backup system that is the same size as the partition that you want to make fault-tolerant (i.e., your data partition). After you have all this equipment, setup is easy. You just pop the Intel Ethernet controllers into each server, connect the two systems via the provided cable, install the software, and mirror the fault-tolerant partition on your primary system to the backup partition on your secondary system using NT's Disk Administrator.

Vinca's interface is easy to use and runs on your standby system. As Screen 1 shows, the StandbyServer Manager main window gives you the system status. You can also easily turn on or off the failover capabilities as Screen 2 shows, fail over to the standby server, fail back to the primary system, or configure the system from StandbyServer's interface.

If you need to fail over an Internet server or software that requires a specific IP address, you can configure Vinca to fail over the primary server's IP address to the backup server. You can also run command (or batch) files when the system detects a problem with the primary server, when the system is failing over to the backup server, after the system fails over, and when it switches back to normal operation.

I tested StandbyServer on two IBM PC Server 704 systems (one 200MHz Pentium Pro, 128MB RAM, two Intel Pro/100B NICs, two Adaptec 2940W SCSI controllers) with Microsoft's SQL Server. Getting SQL Server set up properly can be tricky. You must install SQL Server on both systems and have it use the same drive letter for database storage. I installed SQL Server on the primary system and told it to use the mirrored hard disk (which I set up as drive V) to store its databases. I went to the StandbyServer Manager and failed over the primary system. In this mode, the standby system looked like the primary system and the mirrored partition was available with the same drive letter to the backup system. I then installed SQL Server on the standby system, again using the mirrored drive (drive V) for the databases. After SQL Server was set up on both systems, I brought the primary server back online and remirrored the two systems using NT's Disk Administrator.

On the standby system, I had to configure SQL Server to run only when the primary system fails. From the Services dialog box shown in Screen 3, I set the SQLExecutive and MSSQLServer services on the standby system to start up manually. From Options/Services in the StandbyServer Manager, I selected these two services to start when a failover occurs.

Now that everything was ready to go, I had to arm the system. From the StandbyServer Manager dialog box you see in Screen 4, I selected Armed. I now had a fully working fault-tolerant system running SQL Server.