Disaster Recovery Inside-Out for Dummies (with LSI)

In this article, I'd like to document a setup I have been working on for a few days at the LSI office in Milano (great guys and free beverage there! Thanks!). LSI is the company from which IBM OEMs the DS3000, DS4000 and DS5000 lines of storage servers. Since I am trying to get a little bit more into the storage and network subsystems I wanted to spend a few days playing with those kits. I have concentrated on today's hot topic of Disaster Recovery and particularly the integration of LSI RVM (Remote Volume Mirroring) into the VMware SRM (Site Recovery Manager). I have to admit that I am not a storage guru, nor I have looked too much into SRM, so most of the stuff you will find here might be pretty basic. This is clearly not an advanced read for the likes of Duncan Epping, nor for those that go to bed with the VMware vmkfstools CLI or "talk UUID." (I guess Duncan will get what I mean.) Yet it's intended to provide a bit of background about what happens behind the scenes (the "scenes" would be the GUIs of the various products involved in this case). The SRM part is really focused on the storage integration which was the thing I was most interested in for this 2-day storage marathon. I like to treat these articles as a sort of personal log / documentation of what I have done (for future reference) so it will certainly serve me in the long run. Hopefully it will be of use for some of you, too.

Last but not least, while the bar on the right of your browser might suggest this is long... consider that it's full of screenshots! So without further adieu, let's get started.

Basic Remote Mirror Setup

This part doesn't involve any specific SRM concept in action. It's just meant to describe the basic infrastructure setup (both logical and physical) as well as the way the storage replicates and how the VMware hosts deal with replicated LUNs. It is important to understand what happens at a lower level in order to move on and plug SRM on top of this. The picture below outlines how the logical layout of the infrastructure looks (including SRM):

For completeness, the following picture describes how the physical infrastructure looks instead:

As the picture outlines, the Virtual Center VMs in both sites also host the SRM service. Depending on the scale of your project,t you might want to have dedicated virtual machines to host the SRM instances or even dedicated physical servers. Milano, in our lab scenario, is the primary site while Roma is the DR site. As you can imagine, LUNs need to be replicated from the DS4700 in Milano onto the DS4800 in Roma. LSI calls this storage feature RVM (Remote Volume Mirroring) and it's essentially an advanced function that allows you to keep a copy of your LUNs on a remote storage server.