VMware has been stating that the ESX Service Console (COS) will go away ever since it released ESXi, but so far this has not happened and it doesn’t seem likely to happen any time soon. Despite the session at VMworld this year entitled “How to survive in a COS-less world”, VMware doesn’t seem to be moving that fast to retire the service console. Doing so would be a big change and is only likely to happen with a major new release; VMware had the chance to do this with vSphere but chose not to.
If VMware eliminates the ESX service console, VMware would basically have to retire ESX as ESX without the service console is essentially ESXi. Before I go any further, however, I’ll explain what the service console is and the architecture differences between ESX and ESXi.
At their cores, ESX and ESXi are identical: the VMkernel (which is the hypervisor layer) is the exact same source code and file size for both versions. ESX and ESXi also have a management layer that operates outside of the VMkernel. With ESXi it’s simply called the management interface/console. This management component runs as a privileged virtual machine that has its own operating system and additional VMware management commands.
On ESX hosts, this management component is the service console and runs a modified version of Red Hat Linux taking up several GBs of disk space. On ESXi hosts, this management component is much smaller and is based on an implementation of the Posix variant of Unix within a Busybox framework, which reduces the size of ESXi to approximately 32 MB.
Because of the differences in the management layer some of the administration tasks are different between ESX and ESXi. For example, patching without using Update Manager is different. ESX makes use of a command-line utility called esxupdate, and ESXi relies on a separate update utility that installs with the VMware Infrastructure and vSphere Clients. Web access for VM administration on ESXi hosts is not supported because ESXi does not run a Web application server like ESX does.
Because ESX is running a full OS in the service console, administrators have more flexibility with configuration, scripting, administration and so on. Software and agents (i.e. backup, hardware) can be installed on the service console, which can add additional capabilities to it. This was especially important for monitoring hardware health, but recently VMware has added this capability into both ESX and ESXi so these agents are no longer required to monitor the host hardware.
Essentially, the service console provides administrators with more power and flexibility, which is why many administrators do not want to see it go away. This added flexibility , however, comes with a cost: increased complexity and increased security and operational risks.
VMware has taken steps to get away from the service console by introducing remote management tools such as the remote command-line interface (Remote CLI) , VMware Infrastructure Management Assistant (VIMA) and vSphere Management Assistant (vMA) to take the place of some of the scripting and administration tasks that can be performed inside the service console. But it is still easier in many cases to use the service console than to use the remote management tools. Troubleshooting is much easier when you’re using the service console because of the additional commands that are available.
So when will VMware finally eliminate the ESX service console and fully transition to ESXi? As I mentioned earlier, it is doubtful that this will happen soon as VMware will need to make additional modifications to ESXi to replace some of the functionality that will be missing without the service console, which includes further developing management tools if necessary. My estimate is that VMware may retire the service console with its next major release (vSphere 5?). The one thing I know for sure, though, is that when it does happen there will be many unhappy administrators who will miss their beloved service console.