AiHua Information Technology Site

First, I must remind everyone that most of what goes onto the blog is meant for small to medium sized businesses (SMB) or similarly sized NGOs unless otherwise stated.  For example, I have no qualms about placing an ebox server into an organization up to one hundred people but would seriously consider doing a hand installation of separate openldap, gateway, mail server, jabber, and file servers for organizations of two hundred or more.  This article is such an article about methods for the less than 100 users organization and may not be a good method of setting up servers that have high input and output demands as they may be better served by iscsi, das, or e-sata.

That being said, in the world of 1 Gig switches and ethernet cards, it is easy to create links between computers that ping in less than 0.003 milliseconds.  This is easily fast enough to hold a redundant RAID array of hard drives on a network attached storage drive that shares files to a second, third, or even fourth server accessing those files.  Since a virtual machine is merely a folder and set of files it is trivial to house files on the raid array and then share those files via NFS to more powerful machines that actually host the virtual machines.

The advantage of housing your VM’s in a single location and having multiple virtual hosts is that it is possible to shift virtual machines to make the best utilization of server resources.  The simplist way to achieve this setup is to equip each server with at least two 1 gig ethernet cards and then create direct crossover connections between the NAS and vm hosts like so:

VMHost1<—NAS—>VMHost2
|                           |
——-Switch——–
|
Local Area Network

Remember to have each ethernet set have a different IP set (192.168.1.0 for hosts to switch, 10.0.1.0 for VMHost1 to NAS, 10.0.2.0 for VMHost2 to NAS, etc).  If one of the hosts becomes overloaded or crashes it’s possible to migrate virtual machine to the other now!

For added reliability in the system it’s possible to use a heartbeat to make a redundant NAS setup; however, that is beyond the scope of this article.  Good luck with your own VMHost-NAS, use the “Contact Us” page if you need to discuss help and support options.

I want to take some time to point out that Hamachi is a vpn technology that makes remote access and administration quite easy.  It’s also free for personal use or for use by non-profit organizations!  I have been running some expiriments with this tech and it operates quite well.  I would like to try to integrate it into a gateway to bridge remote offices.  Give it a try by downloading it for windows, linux, and osx @ https://secure.logmein.com/products/hamachi/vpn.asp

I was excited to see that VMware has made their ESXi hypervisor free for installation.  We have been using virtualization technologies for years around the AiHua offices mainly for development work (mostly virtualbox and VMware Server/Player), and recently we have conglomerated our servers onto a single VMware Server 2.0 installation atop a headless Ubuntu 8.04 Server installation.  From there we can host all the individual servers and appliances we need.  It has greatly increased the ease at which we administer our networks.

ESXi will further improve performance and reliability because there is no need to install an underlying server from which VMware Server would need to run.  It also allows setting up extra ethernet cards and iscsi targets in the event of hardware failures.  The only downside is that the VI Client to manage the hypervisor itself is currently Windows only; however, there is a linux version on the horizon which bodes well for organizations looking to free themselves of licensing costs.

The best feature of virtualization comes in the ability to hand over ready made tools to organizations.  Servers can very much become drop in components!  At AiHua Consulting we have even managed to load a few virtual machines onto a VMware server and instantly have a network with pxe boot capabilities, ldap, thin clients, or even NAS/SAN/iscsi.  If the need arises, these parts can be later substituded for real steel hardware (I still like to have a nice RAID array for a storage solution, but in a pinch it’s nice to know I can drop one in as an appliance until I have the bits and pieces for a storage server).

To learn more about how virtualization can help your organization please use the contact us page.