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Setting up the hardware for ServeRAID failover

This page explains how to setup the hardware for a Linux-HA cluster using IBM's ServeRAID cards in clustering mode.

The basic components you need are:

  • 2 servers
  • 2 ServeRAID cards (the same model) that support ServeRAID clustering.

  • 1 or more EXP disk cabinet(s) to hold the shared storage
  • 2 or more disk(s) to go into the EXP cabinet(s)
  • The necessary cables to hook everything up


Make sure you also read the documentation that comes with your equipment. Especially the ServeRAID and EXP users and installation guides.

Minimum requirements

The servers need to at least have a PCI slot free for the ServeRAID adapter. Different ServeRAID cards have different PCI specs with regards to speed and voltage. So make sure your server can handle them. But as always the faster the slot the better.

For details on which cards are supported in clustering mode by Linux-HA see the ServeRAID page for more details.

The EXP cabinet you need depends on the speed you would like. The EXP200 supports Ultra SCSI (80 MB/s), EXP300 supports Ultra160 SCSI and the EXP400 supports Ultra320 SCSI. The EXP300 cabinet automatically supports two SCSI interfaces like are needed for this configruation, but for the EXP400 cabinet, you'll have to add an option not included in the base EXP400 cabinet.

It is best to use disks at the same speed as the EXP cabinet you are using. Another important note here is that the slowest disk will determine the total speed of the SCSI channel. Meaning if you have 5 Ultra320 disks and 1 Ultra SCSI disk, then everything will run at Ultra SCSI speeds, and you won't be using the everything at its maximum speed. Moreover, IBM only tests and certifies these drives and cabinets in matched sets. So, if you want IBM to support your system, make sure you make all the pieces match!

Also the SCSI cabling is important. Make sure you use correct cables, connectors, and terminators as specified in the documentation that comes with your equipment. Bad cabling and bad termination can lead to strange, hard to debug problems.

Connect Your Hardware

The order in which these steps is very important. Failure to do things in the right order will lead to great confusion and frustration, and may require starting the hardware configuration over.

At this point, you can do is to install the ServeRAID cards in the servers, Provide power to the EXP cabinet and put the disks in it, and cable things up according to the documentation which comes with the hardware. Once your hardware is installed, proceed to the next section.

Read your hardware documentation for all the details, but for our purposes, what you're headed towards is to have the three components configured with paul on one end of the SCSI bus, the EXP cabinet in the middle, and silas other end of the SCSI bus.

This means that the SCSI bus should have terminators connected in paul and silas, but not anywhere inside the EXP cabinet.