Avoiding IP Conflicts When Using Virtual Machines

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I thought I had mentioned this tip in a previous post but since a quick search didn’t turn it up I figured I’d add this as its own entry. Not long after I started using virtual machines on a regular basis at work I encountered an IP conflict with a VM and another machine on the network.

The cause was simple. The last time I had used the VM I chose to suspend its state. It retained the IP and tried to use it the next time I started it up.

The solution is also simple. I’ve used this method with both VMWare Fusion and Parallels Desktop for Mac. Every time I prepare to suspend a virtual machine I simply disconnect the VM’s network connection prior to suspending. This will cause it to release the IP. The next time the state is restored and the network is reconnected it should pull a new IP.

It’s worth mentioning that this really only applies to VMs that have IP addresses assigned via DHCP.

UPS Battery Indicator In OS X Restarts Continuously After Launching VMWare Fusion

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The Short Version: The UPS’s USB connection had been inadvertently shared with the virtual machine. Setting it to only be accessible by the host OS (OS X) solved the problem.

Recently I noticed my virtual machine instance under VMWare Fusion (3.1.3) seemed to be running unusually slow on my Mac. Yesterday I noticed that the status indicator for my battery backup kept appearing and disappearing in the menu bar.

While inspecting the energy settings for both OS X (Lion) and Windows 7 (VM) I decided to check the connected USB devices for the virtual machine. Sure enough, my CyberPower UPS was showing as connected to to the Windows 7 guest OS. I have no idea how this happened. There’s no reason I would have intentionally connected the USB interface for the my UPS to to the VM. Perhaps I clicked on it when intending to connect a different device at some point.

Regardless, as soon as I disconnected the UPS from the VM both systems started functioning at a more normal speed and the status indicator stayed in the menu bar instead of restarting.