Here’s a quick tip to start the day!  

I recently found when duplicating a virtual Linux machine using Windows Hyper-v that when the duplicated machine booted, the Ethernet port was disabled?

Watching the boot sequence I saw the following:

Device seth0 has different MAC address than expected, ignoring.

As the new machine has a unique MAC address, the Linux install doesn’t like this and automatically disables the interface!

There’s a quick fix however – you need to edit the file:

/etc/sysconfig/network-scripts/ifcfg-seth0

In this file, change the “HWADDR” entry to match the new MAC address of the virtual network card (you can find this under the settings for the VM).

Finally, restart networking by running :

/etc/init.d/network restart

Had a tough time yesterday getting Homeseer (excellent product!) to talk to my CM11a X10 adapter.   If you’ve never seen one of these – it plugs into the mains and talks to the PC via a serial connection.

Simple – you might think!   However, not so simple when Homeseer is running on a virtual 2008 Hype-V machine!

Eventually got it going using a Lantronix EDS4100 serial over ethernet adapter.   The problem that stumped me for a while though – was that the CM11a needs to run at 4800 baud (not the 9600 default of the EDS).   Anyway – all up and running sweetly now

I still have a small issue of problems with Homeseer running as a service on 2008 – but from the Homeseer forums – looks like I’m not the only one with this issue.

If you’ve never heard of a SAN (Storage Area Network) before, it’s probably because it’s been available only to enterprises with large budgets.

SANs are a way of providing disk based storage via network connections (usually fibre) rather than internally to the machine.   One of the advantages of this is that several machines can access the same “virtual” disk at the same time.   You may wonder why this would be useful as each machine would have a fast local disk anyway? 

Well, when you share a SAN volume, you can enable clustering which means that loads can be shared between machines, and this also provides redundancy should one of them die.

The latest use of SANs however is with the growing adoption of virtualization.   Products such as VMWare and Microsoft’s Hyper V allow many virtual machines (VMs) to run on one physical machine.   When connected to a SAN, it’s easy to move a VM from one physical server to another – and live with no disruption!

So, this brings me back to the cost of SANs.   Typically in the past – a SAN implementation would’ve cost many tens of thousands of dollars and was complex to set up.    This is still the case for large high performance SANs with fibre interconnect and multipath redundancy.

However Starwind have recently released a free version of their iSCSI for Windows.   This allows you to turn any 2TB windows server into an IP based SAN for free!    By using gigabit ethernet instead of fibre, it’s possible to create a Hyper V cluster using 3 machines (one being the SAN server) relatively cheaply.

Congratulations to Starwind on releasing such a product for free!   I can see this bringing live migration and redundant VMs to smaller businesses that previously couldn’t afford it.

I for one will be playing around with this further in our lab….

www.starwindsoftware.com

I’ve seen this happen a couple of times now.   A working Hyper-V server, when restarted, “looses” virtual machines!   No errors, and no trace of the VM! Scary!

Turns out, it’s because the anti-virus software is scanning the virtual machines as they’re loaded and gets in the way.

Here’s a good article describing the problem and which folders you need to exclude from the AV scan:

http://social.technet.microsoft.com/Forums/en-US/winserverhyperv/thread/e81d0f59-18b5-4214-94ea-6cde883fdd4e