Informational GuidesvCenter Server

What if vCenter Server is Down & What are the Impacts ?

Every organization who uses vSphere in their environment they have vCenter Server to manage all of their virtual infrastructure from single point. vCenter provides centralized management of all the vSphere objects. In this post we will see on what are the Impacts if vCenter is down or vCenter is not available or when vCenter Server is offline.

vCenter adds features to your vSphere Infra such as vMotion, DRS, HA, FT etc. So for configuring & using this features vCenter is must for you. This all features provides availability, load balancing & various functionality to your ESXi hosts & virtual machines. So you can say that vCenter is very critical part of your Infrastructure.

vCenter is crucial in every environment and provides easier management of ESXi hosts & virtual machines. If you don’t have vCenter in your environment then you will have to login to each ESXi hosts to create & manage virtual machine plus you will not get benefit of many features which are only available in vCenter Server.

So let’s see which of the features & functionality will work when vCenter is down & will not work when vCenter is down:

Central Management:
vCenter’s main benefit is to provide the Central management of all your vSphere objects. So in case if vCenter Server is down or not available you will not be able to manage all the objects centrally instead you will have to login to each ESXi host to manage virtual machines and other objects.

ESXi hosts:
ESXi Hosts are independent servers which are added to vCenter to manage all the hosts from single pane. So if in case if vCenter is down ESXi hosts will not have much impact they will run smoothly. If you have large number of ESXi hosts then it will be very complex situation to manage ESXi hosts.

Virtual Machines:
Virtual Machines are deployed on ESXi hosts but you use vCenter server to create & manage virtual machines. So if vCenter is down your virtual machines will run without any impact but you will need to login to each ESXi hosts to manage your VMs. If you have large number of virtual machines running on each ESXi host then it will be very difficult for you to find and manage virtual machines.

Clone & Template:
Clone & Template are very useful feature when you want to perform large deployment. But if vCenter is not available then you can not clone a VM & you will not be able to Deploy VM from Template.

Snapshot:
Snapshot will not have any such impact if vCenter is down. You can still login to ESXi host to create Snapshots of virtual machines.

vMotion & Storage vMotion:
vMotion & Storage vMotion are features of vCenter Server which provides migration functionality to virtual machine & it’s storage. So if vCenter Server is not available you will not be able to do any vMotion or Storage vMotion.

DRS & Storage DRS:
DRS & Storage DRS are also features of vCenter Server which provides automatic load balancing of Clusters & Datastore clusters by migrating VMs & VMs Storage. So if vCenter is down then DRS will not be able to balance the load of ESXi hosts & Storage DRS will not be able to balance the load of datastores.

HA (High Availability):
HA is the feature of vCenter Server which provides the availability for your virtual machines in case of ESXi host failure. HA is dependent on vCenter Server to monitor protected virtual machines. So if vCenter is down then currently protected virtual machines will be restarted on other ESXi hosts but you will not be able to protect any new virtual machines until vCenter is available. Also you won’t be able to make changes to any HA feature such as Admission Control.

FT (Fault Tolerance):
FT is also the feature of vCenter Server which provides the complete availability for virtual machine. In FT is primary VM is down then secondary VM will take over to provide the availability. So in that case if vCenter server is not available then FT will continue to run & secondary VM will be available in case of primary VM failure but without vCenter new secondary will not be created. Also you won’t be able to make changes in FT Configuration.

vSS (vSphere Standard Switch):
vSS is created & managed at the ESXi host level & it provides connectivity to virtual machines. But if vCenter Server is down there will be no impact on vSphere Standard Switch. You can make any changes to vSS by logging into ESXi hosts.

vDS (vSphere Distributed Switch):
vDS is created and managed by vCenter Server only & if you don’t have vCenter you can not use vDS in your environment. Main functionality of vDS is to provide centralized network management for all the ESXi hosts & Virtual machines. So if vCenter Server is down then your ESXi & VMs network connectivity will not be impacted but you will not be able make any changes in vDS settings.

VUM (VMware Update Manager):
From vSphere 6.5 & later VUM is completely integrated into vCenter Server. VUM is used to patch & upgrade ESXi hosts in your environment. So if your vCenter is not available you can not patch or upgrade ESXi hosts using VUM but you will have to choose different ways such as command line. vCenter is not available then you will also not be able to use the Maintenance mode to migrate VMs you will have to shutdown the virtual machines.

 

You have seen above impacts of features & functionality on your vSphere Infrastructure if vCenter server is not available. It is very important for you to have your vCenter Server available at all the times.

So how you can protect your vCenter Server from failure or downtime:

One of the best feature from vSphere 6.5 & later to protect vCenter is VCHA (vCenter High Availability) yes you can make your vCenter highly available by configuring VCHA in your environment. (VCHA only supported in VCSA not supported in windows based vCenter)

You can check below links as well on What is VCHA & How to configure VCHA step by step:

What is VCHA ?

How to Configure VCHA Step by Step ?

Other things you can do is to take backup of vCenter Server so in case of disaster you can use backup to restore vCenter Server. Backup & Restore is now part of vCenter Appliance so you don’t have to depend on the third party backup solutions. (Backup & Restore functionality is only available in VCSA from vSphere 6.5 & later)

You can just login to your vCenter Server Appliance Management & configure Backup directly & if you are using vSphere 6.7 then you can also schedule backups.

You can check below link on How to Backup & Restore vCenter using vCenter Appliance Management :

How to Backup & Restore VCSA 6.5 Step by Step ?

 

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Mayur Parmar

Hi I am Mayur Parmar. Independent Author & Founder of Mastering VMware. I am working in IT industry for more than 4 Years with knowledge of VMware , Microsoft Server's, Linux Server's.

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2 Comments

  1. Hello Mayur,
    A very nice topic which provides a good information on howto run your vSphere environment should an issue will arise.

    Paul Vincent A. Fajardo

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