Configuring Highly Available iSCSI Storage for VMware ESX Server 4.0

You have experience with VMware ESX Server. Who doesn’t? But suppose you’re tasked with the exciting job of adding a new VMware ESX server to your cluster. On top of that, you need to create a new iSCSI LUN that this server will use for VM storage. Although you use VMware ESX Server every day to administer your virtual machines (VMs), you don’t build new VMware ESX servers very often, and you’re rusty on the skills necessary to connect a new server to your iSCSI SAN. The process isn’t necessarily challenging, but some of the steps aren’t obvious—and completing them in the correct order is important. This article will help get you going.

The Sample Environment

Before getting into the step-by-step instructions, let’s take a look at a sample environment. Figure 1 shows a graphical representation of an environment in which two servers are running StarWind Software’s iSCSI SAN software. I’m using StarWind’s solution in my example and in this article, but understand that every iSCSI SAN will offer a unique management console. The experience will be different, but the steps will be similar. (You can download a copy of StarWind’s product at www.starwindsoftware.com. It installs to any Windows server and will give you a general idea of how SAN configuration works.)

 

 

Configuring the LUN

You need to create a redundant iSCSI LUN, so you’ll need to create a LUN that’s mirrored between the two SAN servers.

In the StarWind Management Console, ensure that you’ve added and connected to both hosts. If you're using the trial version of StarWind, the default logon and password are root and starwind, respectively.

1. Right-click Targets and select Add Target. In the resulting screen, you’ll be asked to provide a Target Alias and Target Name. The Target Alias is the friendly name for the iSCSI LUN you intend to create and is generally used only on the SAN device. The Target Name will be the iSCSI Qualified Name (IQN) used for the server-to-storage connection; it's the name you’ll find yourself seeing inside VMware ESX. You can safely leave the check box next to Target Name blank, allowing StarWind to create that IQN for you.
2. Set Storage type to Hard Disk.  Then, set Device type to Advanced Virtual and then a High Availability device.  These high-availability options will be available if you are using the Enterprise HA edition of the StarWind SAN software. Creating a highly available LUN between two servers requires configuring that LUN with two partners. The first partner will be the server you used for the initial target creation. The second server is configured as a partner server. In this screen, provide the host’s name as well as a username and password. You can use the same default username and password you used earlier, as long as it hasn’t been changed.
3. Creating this partner connection requires also creating a Partner Target Alias and Partner Target Name, which must be different than in the earlier step. By default, the console will append the word Partner to your previous name.
4. You need to define the location where StarWind will store the file that will eventually become your VMware ESX LUN. You’ll also need to configure how large you want that LUN to be. Figure 2 shows those configurations for both servers. Although the figure shows storage of those files on the two servers' C drives, your production configuration should obviously be set to a separate data drive.
5. You also need to configure the data synchronization channel parameters, which are effectively the target’s network settings for the LUN. Figure 3 shows that an interface is configured for both partners by IP address. You can also identify which partner is primary versus secondary, as well which port number is used for iSCSI traffic.
6. The StarWind Management Console next asks how you want to initialize the disks. Because these are brand-new disks, select Clear virtual disks. Click Next through the following series of screens, then Finish to complete the LUN creation. StarWind will require a number of minutes to synchronize between the two servers. Allow this process to complete. You’ll know the process is over when the yellow or green warning symbols next to each target have disappeared.