ZeroShell: DoubleTake Flex Boot Buddy

ZeroShell: Double-Take Flex Boot Buddy

DHCP For Double-Take Flex In A HyperV VM

Above: Booting bare metal from Flex - DHCP courtesy of ZeroShell

A request came in recently that gave us that horrible sinking feeling...

When using Doubletake Flex to boot servers from bare metal - for some reason, on boot up, the bare metal servers would not be given an IP from the subnets DHCP server. Nothing really bad about that we thought - until we learnt that the DHCP server in question was of the 'Windows 2008 R2 Active Directory linked' variety. Now for one reason or another, we've never had much joy with using Windows based DHCP servers and Flex - it's just a complete pain. Fortunately, we have always been able to architect our way around the problem - by arguing the case for completely separating iSCSI traffic from OS type traffic.

Why do people want to use Windows? Not really a matter of 'want' but just that 'it's there'. There is a working Microsoft DHCP server on site, so it's jolly tempting to create scopes for both the iSCSI boot network, and the 'OS' network on this. But in our experience, this just leads to trouble - and with Windows 2008R2 - it's even more of a pain. There is quite a bit of security 'Network Access Protection' built in to Windows 2008 R2 DHCP, you will need filters, and perhaps to disable other stuff to even start to try to get it to work. So trust us - you're better off leaving Windows to service your OS level clients, and give Flex something dedicated to play with. That you can even tinker around with - without creating a queue of angry people outside your door all asking why they can't log on the network!

If you are, like many, making use of Microsoft Windows 2008 HyperV - then here's a neat little solution that will get you out of having to touch any more hardware in order for you to set up a standalone DHCP server for your Flex system:  Download a Linux based 'mini firewall appliance' and give Flex the exclusive DHCP services it deserves - all from very modestly specced HyperV VM.

The particular Linux based appliance here is called 'ZeroShell' and we have been using it for a few years now. It's very stable, and, unlike some other Linux appliances out there, it can work fine configured with a single interface. ZeroShell can also operate as a VPN server if enabled, so you could use it as a VPN concentrator to get even more secure access to your iSCSI network from outside. It's also does many other useful tasks, including that of firewall, there's a timeserver, and it can talk VLANs - so we're confident it will suit any kind of setup.

For our test, we downloaded the ISO version of ZeroShell 1.0 beta 12 - which you can get here:

http://www.zeroshell.net/eng/download/ 

We ran through the entire procedure today, which took about 10 minutes to get working.  

We took screen grabs along the way, which you can click through at the bottom of this post. If you are planning on deploying this - hopefully we have provided enough information for you to get it working.

Of course, if you've like a bit of help with this - or any other Flex-isum - why not use the contact us link on the right to get in touch?