VMware vSphere 4 gives us the ability to actively use multiple iSCSI paths to reach a single LUN. You will need to use vSphere Client, your iSCSI storage management tools, and an ESX command-line interface (such as ssh, RCLI or vSphere Management Assistant) to get it working. This procedure can be used to add up to eight iSCSI paths per datastore, provided each path uses a unique physical NIC and that each physical NIC has a corresponding NIC on the iSCSI SAN side. In other words, setting up more paths on the VMware side than your iSCSI SAN can actually accommodate would be pointless.
This tutorial assumes that you are familiar with vSphere Client and can find your way around. Read on beyond the break.
I picked up a VirtualBox Windows VM optimization tip from the MacEnterprise mailing list this morning, supplied by Yadin Flammer. Yadin mentioned that switching your Windows VM’s disk type from the default IDE to SATA and using the Intel Matrix Storage drivers results in faster hardware emulation. I decided to verify this claim by collecting some before and after I/O data. I have a Windows XP VM, but this should apply to all versions of Windows from 2000 onward, both server and client.
I used the freely-available Iometer to gather my disk I/O data. Both the before and after tests were run for 5 minutes on an ~ 3GB test file using the All-In-One test suite. Here are the results.
As you can see, the data clearly shows a slight increase in performance. Using SATA is actually recommended by Sun, as well. On this page, they say,
Like a real SATA controller, VirtualBox’s virtual SATA controller operates faster and also consumes less CPU resources than the virtual IDE controller. Also, this allows you to connect more than three virtual hard disks to the machine.
Makes sense, no? In terms of MBps, my IDE test averaged 17.925 while my SATA test averaged 18.828. Now that we know it’s better, we’ll move on to the installation and configuration procedure.
Installation and Configuration
- Shut down your Windows VM and open its settings window (shown above).
- Select the Hard Disks item, check Enable Additional Controller and choose SATA (AHCI) from the list.
- Leave the Hard disk attached to the IDE Controller in the Attachments section for now, since we’ll first have to install the SATA drivers, and click OK.
- Start up your VM again and download the Intel Matrix Storage Manager drivers. Click the link, select your Windows OS version, click Go, and then click the first download link in the Drivers section. Mine showed up as link #1. Save it to your desktop, and then install it. NOTE: If you are given a warning about not meeting the minimum installation requirements, you may need to download and install the Intel Chipset Software Installation Utility first. Follow the same download and install procedure as for the storage drivers.
- Once the drivers are installed, shut down your Windows VM and open its settings window.
- Select the Hard Disks item as before, but now select SATA Port 0 next to your VM’s .vdi file in the Attachments section.
- Click OK and then start up your VM.
… And boom goes the dynamite.