Building an Inexpensive Two-Node Server Cluster

Articles and Tips: qna

01 Apr 2001

Dear Ab-end: I'm trying to build a "poor man's" cluster. Basically, it's a two-node SCSI-based cluster solution. Do you have any ideas how I can get this working? - Trying to Cluster on a Shoe String

Dear Shoe String: I do know of a working cluster similar to what you describe. Here's how it was done.

The first server is a Pentium II 233 clone system using an IDE hard drive for the SYS volume. This system has an Adaptec 2940U2 controller in it, configured as SCSI ID 6, with an external SCSI cable running to an external SCSI HD cabinet. The external case holds one SCSI HD that is configured as SCSI ID 0.

Server 2 is a Pentium III 550 clone system using an IDE hard drive for the SYS volume. This system also has an Adaptec 2940U2 controller, configured as SCSI ID 7, and an external SCSI cable running to the other connector on the external SCSI HD cabinet.

By the way, the administrator of this cluster tells me he should have used SCSI "Y" cables so that one end of the Y would plug to the HD cabinet and the other Y end would plug to the Adaptec card, with the Y going to an external terminator. But, he says, he was too cheap to do this. So, if he powers off either machine, the SCSI bus also loses power, and the other machine hangs up.

At any rate, the SCSI cards are configured as follows:

Termination is set to AUTO
Disable Plug and Play SCSI IDs (if that option is available)
Parity is ENABLED (but he doesn't think this matters)
Disconnection is DISABLED
Send Start Unit CMD: NO
BIOS is disabled (not booting from this drive)
Reset SCSI bus at Init: Disabled

The driver is AIC78U2.HAM version 6.10, 11/1/99.

Now, here's the secret to making it work:

Boot Computer 1, but do not start the server.
Boot Computer 2. You can let the server start and come all the way up.
Start the server on Computer 1.

Video fail-over depends on what client OS you're using. If you're using Windows 95/98, you will have a pause due to the file-level mechanism that it uses. Windows NT, on the other hand, uses a volume level mechanism, and the results will be different during fail-over. (Answer supplied by Stephen Payne and Bryon Griffin of Novell, Inc.)

* Originally published in Novell AppNotes

Disclaimer

The origin of this information may be internal or external to Novell. While Novell makes all reasonable efforts to verify this information, Novell does not make explicit or implied claims to its validity.