Deep Intro to VMware ESX, Part 3

Now you have your ESX server partitioned you can start deploying more ESX server to build a complete farm of servers that can work together. Especially when you use the enterprise edition of Vmware ESX this can be very helpful. The enterprise version has Vmotion capabilities. When one ESX server goes down Vmotion transfers the session on that to another ESX server.

End users will not experience any down time.

In this case we need a VMware VirtualCeneter server that manages the various hosts.

Install and configure a Windows 2003 server and install Microsoft SQL server or SQL express on that computer. This computer may be a virtualised server and actually running on a ESX server. But keep in mind that the session will get lost if you put the machine in Maintenance mode or the ESX server crashes. This is because VMware Vmotion needs a few seconds to determine on which host the session can run best and the Virtual center server will not be moved at all.

It is best practice when you use VMware ESX enterprise to put the VirtualCenter server on a physical server.

When you have deployed several VMware ESX hosts, and you also have installed and configured a VMware Virtual Center server, you have to add the hosts to the Virtual Center server by selecting add host.

Then you also have to add the storage to the Virtual center server.

Then all the ESX servers have access to that storage. The Virtual machines reside on the SAN and the Vmware ESX servers will start up these VM's as needed.

You will have the best performance when you add the SAN by using the fibre channel connectors. These FB connectors are usually 2 GB, 4 GB and the latest are even 8 GB connectors. They have very high throughputs.

On multiple VMware ESX Server configurations with shared fibre channel storage, the following issues and restrictions apply:

All the VMs on one logical drive are executed on the same ESX Server at one time.

If an ESX Server has any local/public files on the fibre channel box, create a server group for it, and a logical drive for it. Make vmfs partitions on that logical drive of accessibility type public if possible. VM clusters might require accessibility type shared (Windows ones do). You could have other file systems such as ext3 for VM configs there, too.

All storage shared between VMs on different ESX Servers (i.e. storage failing over between cluster nodes, or similar) should be placed on separate dedicated logical drives. This is because logical drive is the smallest possible disk unit to move (fail over and back) between ESX Servers.

On the fibre channel configuration place all the ESX Servers to the same server group so that they can all potentially access the same logical drives even at the same time, if required.

Network: setup and configuration-related issues

Next step in our process is to make sure we have configured our Network cards correctly. Most current ESX servers have 2, 4 or even 6 NICS. In the case that the server has 2 nics on board and 2 or 4 nics with an add on card it is best to use one onboard nic where you configure the service console.

Then use the second on board nic to configure the VMkernel. The service console will ensure you access to the service console on the Vmware ESX server. The VMkernel is used for Vmotion, High availability and Disaster and recovery.

Then you will be able to configure the 2 or 4 add on nics teamed to the virtual machines to get the highest availability and data throughput.

Please consider the following issues:

The sharing resolution for PCI devices is one card. Netcards cannot be shared between Service Console and VMs, but SCSI cards can be shared.

For multiport NICs the sharing resolution is a single port.

It is strongly recommended to set the speed and full duplex setting for each physical netcard.

Service Console netcard settings are set in the Service Console /etc/modules.conf file. Occasionally you might want to change some options for speed or duplexity.

Best possible performance is obtained if each VM is allocated its own netcard. Usually this is not possible. The next best thing is to limit the network speed allowed for each VM sharing a physical netcard (or port of a card). ...But. Only limit the speed if you need to. Most of the time only busy fileserver VMs eat up the full network bandwidth.

Remote console uses port 902/tcp by default, so it, and ports 22/tcp, 80/tcp, and 443/tcp should be open to the ESX Server Service Console netcard.

In the next article I will show you the default directories on the VMware server and some very useful commands that help you manage ESX servers from the console.

You can read Part 2 here: Deep Intro to VMware ESX, Part 2