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.

From Virtualbox to Fusion (and thoughts on mControl)

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I wanted to improve the performance of my Windows 7 virtual machine so I decided to look at moving to Parallels Desktop for Mac or VMware Fusion. VMware had a special upgrade offer for current users of Parallels. While I wasn’t using Parallels I did have a license for version 2. The “upgrade” cost for Fusion 3 under this deal was only $20 so I went ahead and purchased it.

Performance of the virtual machine in Fusion does seem to have improved over Virtualbox. However, I am still experiencing some nagging lags even with Fusion. Of course, this is further complicated by the fact that my host Intel iMac only supports a max of 2 GB of RAM and Windows 7 requires 1 GB. Overall, it’s been tolerable but host OS performance has been suffering.

I don’t remember the specifics of how I migrated the hard drive image into Fusion but I think it was just a matter of setting up an existing virtual machine and allowing Fusion to acquire the disk image.

I tracked down one VM setting change that seems to have helped with performance of the host OS with very little impact on the guest OS (except for the fact that it re-installed some drivers, which messed up activation of one product). The only change I’ve made was to disable Hard Drive Buffering under the Advanced settings. Your mileage may vary. I suspect that systems with better specs will benefit from having that option enabled.

I’m still trying to decide the future of my home automation software. I like mControl but I’m starting to lean toward something that is OS X native. I don’t really want to have a Windows 7 system just to run one software package and I’m also frustrated with how the license is managed in mControl 2. It seems that any minor change to the hardware (or virtual hardware) will cause it to think it’s on a new machine and require re-activation. Correcting this is ridiculously simple, but still annoying. It’s hard to abandon a software package that originally cost over $100 but it’s also becoming less relevant to my home computer/home automation environment.