What if vCenter Server\Appliance is Down?

The best thing about Vmware platform is the centralized management of all the resources using vCenter Server. Using vSphere or Web Client we all connect to vCenter Server to administer the virtual datacenter. Imagine if there was no vCenter Server and we had to connect to each ESXi host manually and manage the VMs. Yes, it sounds like a tedious task.

vCenter Server also provides multiple features like DRS, sRDS, vMotion, HA, FT etc. Today we are talking about a scenario where the vCenter Server or Appliance goes down and what are its impact on each of these functionalitiess. Let's check the impact of each of these functionalities below

Management :

Managing the environment won't have much impact as we can still connect to each ESXi host via SSH or vSphere client and manage the servers. It is not easy but there is no impact to the environment

Virtual Machines & ESXi Hosts:

There is no dependency of vCenter server on functionality or uptime of any other Virtual Server or ESXi Host. The Hosts can still be connected via SSH or vSphere Client and all the Virtual machines are still working

Distributed Resource Scheduling:

DRS works with vCenter Server to balance the resources and Virtual Machines across ESXi Hosts using DRS Clusters, the DRS functionality will fail if the vCenter server is down

vMotion\svMotion:

vMotion and svMotion features are spanned across hosts and since it is a feature is based on DRS, Both vMotion and svMotion will fail if vCenter server is down

High Availability:

HA will have medium impact as the Hosts\Clusters configured with HA enabled will have the HA running even if vCenter Server is down. However we would not be able to change any settings like Admission Control Policies while the vCenter Server is down.

Fault Tolerance:

FT will also work in case of all Virtual Machines which are configured before vCenter Server went down. No Changes can be done once the vCenter server is down.

Distributed Switch:

Distributed Switch would still continue to work even after vCenter Service is down. It will still connect to the Network it is configured on.

VM Snapshots:

There would be no issues in taking the snapshots of a Virtual Machine. We need to connect to ESXi host and take the VM snapshot.

Virtual Update Manager:

Since Virtual Update Manager is a vCenter plugin, the functionality of VUM will fail while the vCenter is down.

Note:

We have tested these features and impacts mentioned above only on vCenter Server 5.x version only.