The IBM EXP400 expansion cabinet is suitable for use with ServeRAID cards operating at SCSI speeds up to 320 mbytes/sec. It only comes with sufficient connectors, etc. to accomodate connections from a single SCSI card. You'll have to buy the appropriate accessory to connect more than one adapter to a single EXP400. The ServeRAID resource agent requires that you configure it as a single twin-tailed SCSI bus.
You can read more about it on the IBM web site.
Note that this page says it supports twin-tail buses directly, but some versions of the EXP400 require an added ESM to do this.
**Explanation** Some EXP400 models ship standard with two ESM modules (you need one module for each SCSI connection that you make to the unit) while others come with only one. Models 1RU and 1RX come with a single ESM, 2RX comes standard with both ESMs. For clustering you need two ESMs and you can buy the second one separately if necessary (p/n: 59P5018). -Ellen Gardiner
In the end, you want this configuration to look logically like this:
[ EXP400 Enclosure ] [host1]------[(esm)-disk-disk-disk-disk-(esm)]------[host2]