I'm working on a project which aims to make use of Ubuntu servers running on enterprise class hardware. In our case that means IBM HS23E blade servers, QLogic 4GB fibre channel extension cards and quite old IBM DS4500 disk array with two controllers. At the moment we have fibre channel as only boot option and Ubuntu Server 12.04 installed just fine and is able to boot without multipath. I'm not a linux professional myself but in our team we have people who will understand the technical stuff. Don't let my post confuse :)

The current situation is that we have only one fibre channel connection to a single disk array controller. Real life case would be of course quite different. At minimum we should have two fibre channel ports connected to two different switches and two different controllers.

However, we have no idea how to set up multipath tool. Is the DM-MPIO the right software? At minimum we should be able to boot when multiple connections are available and achieve fault tolerance when any of them should be down.

Since the disk array is not the latest hardware, I managed to find RDAC driver sources only for 2.6.x kernel. And we have 3.2.x. Another issue is to build a multipath.conf. The said driver sources are from IBM support and the QLogic drivers provided to Ubuntu installer are from Ubuntu site. It seems that RHEL and SLES would have near out of the box support but that is not an option for our project.

Actual questions: - What is the recommended software tool for multipath for Ubuntu Server 12.04? - Is there available pre-made configurations or templates? Does it require disk array / controller specific settings or do a more generic config work? - Do you have expriences on similar setup and like to share the knowledge?

I'll provide you with any additional information you might require. Thanks in advance.