Managing Multiple ESXi Hosts with vCenter Server

Introduction

In virtual environments, especially large and complex infrastructures, managing multiple ESXi hosts is crucial. Managing individual ESXi hosts can be time-consuming, inefficient, and prone to errors. This is where vCenter Server comes into play. vCenter Server is the central management tool of vSphere, VMware's virtualization platform. vCenter Server makes it possible to manage multiple ESXi hosts, virtual machines (VMs), storage resources, and networks from a single interface. This increases operational efficiency, optimizes resource utilization, and simplifies overall infrastructure management.

In this article, we will examine in detail what vCenter Server is, its benefits, how to install it, configure it, and how to use it to manage multiple ESXi hosts. We will also help you better understand the subject with real-life examples and case studies.

What is vCenter Server?

Definition and Functions of vCenter Server

vCenter Server is the central management platform of the VMware vSphere environment. It is used to manage one or more ESXi hosts, create, configure, monitor, and move virtual machines. vCenter Server is the heart of the vSphere environment and ensures that the virtualization infrastructure operates efficiently and reliably. Its main functions are:

Central Management: Managing multiple ESXi hosts from a single interface.
Virtual Machine Management: Creating, configuring, starting, stopping, cloning, moving, and deleting VMs.
Resource Management: Managing and optimizing CPU, memory, storage, and network resources.
Monitoring and Reporting: Monitoring and reporting the performance of ESXi hosts, VMs, and other vSphere components.
High Availability (HA) and Distributed Resource Scheduler (DRS): Ensuring high availability of VMs and automatically distributing resources.
Update Management: Keeping ESXi hosts and VMs up to date.
Security Management: Ensuring the security of the vSphere environment.

Benefits of vCenter Server

There are many benefits to using vCenter Server:

Increased Efficiency: Thanks to central management, system administrators can do more work in less time.
Optimized Resource Utilization: Thanks to DRS and other resource management features, resources are used more efficiently.
Improved Reliability: Thanks to the HA feature, VMs are not affected by hardware failures.
Simplified Management: Managing the entire vSphere environment from a single interface reduces complexity.
Reduced Costs: Thanks to less hardware, less energy consumption, and less management costs, the total cost of ownership (TCO) is reduced.

vCenter Server Types: vCenter Server Appliance (vCSA) and Windows-Based vCenter Server

There are two main deployment options for vCenter Server:

vCenter Server Appliance (vCSA): A Linux-based, pre-configured virtual machine. It is easier to install and configure, and generally consumes fewer resources. VMware recommends vCSA as the default deployment option.
Windows-Based vCenter Server: A vCenter Server installed on Windows Server. It was commonly used in older versions, but its use is gradually decreasing due to the advantages of vCSA.

Comparison Table:

Feature	vCenter Server Appliance (vCSA)	Windows-Based vCenter Server
Operating System	Linux (Photon OS)	Windows Server
Installation	Easier and faster	More complex
Resource Consumption	Less	More
Update	Easier	More complex
Recommended Use	New installations and migrations	Legacy systems (decreasingly)

vCenter Server Installation and Configuration

Hardware and Software Requirements

Before installing vCenter Server, make sure you meet the hardware and software requirements. Requirements may vary depending on the vCenter Server version and the size of your environment. You can find the most up-to-date requirements in VMware's official documentation. In general, you will need:

Server: A server with sufficient CPU, memory, and storage space.
Operating System: VMware Photon OS for vCSA (comes with vCSA) or a supported Windows Server version for Windows-Based vCenter Server.
Database: vCenter Server needs a database to store its data. Supported databases include VMware vPostgres (comes with vCSA), Microsoft SQL Server, and Oracle Database.
Network: A network that can communicate with ESXi hosts and other vSphere components.
DNS: A DNS server for proper resolution of vCenter Server and ESXi hosts.

vCenter Server Appliance (vCSA) Installation Steps

Download the vCSA ISO file: Download the vCenter Server Appliance ISO file from VMware's website.
Mount the ISO file: Mount the downloaded ISO file to a virtual drive or burn it to a DVD.
Launch the setup wizard: Open the "vcsa-setup.html" file from the mounted drive in a web browser.
Start the installation: Click the "Install" option in the setup wizard.
Follow the stages: Follow the instructions in the setup wizard. There is a two-stage installation process:
- Stage 1: Deploy the vCSA virtual machine to an ESXi host or vCenter Server.
- Stage 2: Configure the vCSA (network settings, database settings, etc.).
Enter the required information: The setup wizard will ask you for various information, such as:
- The IP address or FQDN of the ESXi host or vCenter Server
- The username and password of the ESXi host or vCenter Server
- The name of the vCSA virtual machine
- The password of the vCSA virtual machine
- Network settings (IP address, network mask, gateway, DNS server)
- Database settings (if you are using an external database)
Complete the installation: After entering all the information, complete the installation. The installation process may take some time.

Configuring vCenter Server

After vCenter Server is installed, you need to configure it. The configuration steps are as follows:

Open vSphere Client: Go to the IP address or FQDN of the vCenter Server in a web browser and open the vSphere Client.
Log in to vCenter Server: Log in to vCenter Server with the username and password you specified during installation.
Enter the license key: Enter a license key to activate vCenter Server.
Create the data center: Create a data center in vCenter Server. The data center is used to group ESXi hosts, VMs, and other vSphere components.
Add ESXi hosts: Add ESXi hosts to the data center.
Configure network and storage settings: Configure network and storage settings according to your vSphere environment.
Configure users and roles: Configure users and roles to control access to vCenter Server.

Updating and Patching vCenter Server

Keeping vCenter Server up to date is important for security and performance. To update vCenter Server, follow these steps:

Open vSphere Client: In a web browser, navigate to the IP address or FQDN of the vCenter Server and open the vSphere Client.
Log in to vCenter Server: Log in to vCenter Server with your username and password.
Open Update Manager: From the "Menu" menu, select "Update Manager".
Create a Baseline: Create a new baseline. This baseline will contain the updates and patches to be applied.
Scan ESXi Hosts: Scan the ESXi hosts to determine which updates and patches are required.
Apply Updates: Apply the necessary updates and patches to the ESXi hosts. This process may require restarting the ESXi hosts.

Managing ESXi Hosts with vCenter Server

Adding ESXi Hosts to vCenter Server

To add ESXi hosts to vCenter Server, follow these steps:

Open vSphere Client: In a web browser, navigate to the IP address or FQDN of the vCenter Server and open the vSphere Client.
Log in to vCenter Server: Log in to vCenter Server with your username and password.
Select the data center: Select the data center to which you want to add the ESXi host.
Start the Add Host wizard: Click "Add Host" from the "Actions" menu.
Enter the ESXi host information: Enter the IP address or FQDN, username, and password of the ESXi host.
Assign a license key: Assign a license key to the ESXi host.
Complete the setup: Complete the setup.

Configuring ESXi Hosts (Network, Storage, Security)

You can configure ESXi hosts through vCenter Server. The settings you can configure include:

Network: Virtual switches, port groups, VMkernel adapters, and physical network adapters.
Storage: Datastores, storage adapters, and storage paths.
Security: Firewall rules, user permissions, and certificates.

Example: Creating a virtual switch on an ESXi host (command line):


esxcli network vswitch standard add --vswitch-name=vSwitch1

Monitoring and Managing ESXi Hosts

vCenter Server provides various tools for monitoring and managing the performance of ESXi hosts. The metrics you can monitor include:

CPU usage: Shows how much of the ESXi host's CPU is being used.
Memory usage: Shows how much of the ESXi host's memory is being used.
Disk usage: Shows how much of the ESXi host's disks is being used.
Network usage: Shows how much of the ESXi host's network is being used.

Here are the tools you can use to manage ESXi hosts with vCenter Server:

vSphere Client: Graphical user interface used to manage ESXi hosts.
vSphere CLI: Command-line tool used to manage ESXi hosts.
PowerCLI: PowerShell module used to manage ESXi hosts.

Putting ESXi Hosts into and Taking Them Out of Maintenance Mode

Putting ESXi hosts into maintenance mode is used to safely move VMs before performing maintenance or repair operations on the host. To enter maintenance mode, follow these steps:

Open vSphere Client: Go to the IP address or FQDN of the vCenter Server in a web browser and open the vSphere Client.
Log in to vCenter Server: Log in to vCenter Server with your username and password.
Select the ESXi host: Select the ESXi host you want to put into maintenance mode.
Enter maintenance mode: From the "Actions" menu, click "Maintenance Mode" -> "Enter Maintenance Mode".
Move VMs: Before entering maintenance mode, move all VMs on the ESXi host to another host. If DRS is enabled, the VMs will be moved automatically.

To exit maintenance mode, follow the same steps and click "Maintenance Mode" -> "Exit Maintenance Mode" from the "Actions" menu.

Virtual Machine Management (VM)

Creating, Configuring, and Managing VMs

You can create, configure, and manage VMs with vCenter Server. To create a VM, follow these steps:

Open vSphere Client: In a web browser, navigate to the IP address or FQDN of the vCenter Server and open the vSphere Client.
Log in to vCenter Server: Log in to vCenter Server with your username and password.
Select the datacenter or host: Select the datacenter or host where you want to create the VM.
Start the VM creation wizard: Click "New Virtual Machine" from the "Actions" menu.
Specify the VM's name and operating system: Give the VM a name and specify which operating system you will install.
Configure hardware resources: Configure how much CPU, memory, disk space, and network adapter to allocate to the VM.
Complete the setup: Complete the setup.

You can change the VM's hardware later. Select the VM, click "Edit Settings" from the "Actions" menu, and change the hardware settings.

Cloning VMs and Creating Templates

Cloning VMs is used to create a copy of an existing VM. Creating a template is used to save a VM as a template for later use. Cloning and template creation speed up VM deployment and ensure consistency.

VM Cloning:

Select the VM you want to clone.
Click "Clone" -> "Clone to Virtual Machine" from the "Actions" menu.
Give the new VM a name and select the target host.
Configure the cloning options (e.g., full clone or linked clone).
Complete the cloning process.

Creating a VM Template:

Select the VM you want to use as a template.
Shut down the VM.
Click "Template" -> "Convert to Template" from the "Actions" menu.
Confirm.

Moving VMs (vMotion and Storage vMotion)

vMotion is used to move a running VM from one ESXi host to another without interruption. Storage vMotion is used to move a running VM's disks from one datastore to another without interruption. These features are important for planned maintenance and resource optimization.

vMotion:

Select the VM you want to move.
Click "Migrate" from the "Actions" menu.
Select the "Change compute resource only" option.
Select the target host.
Review the compatibility checks.
Complete the migration process.

Storage vMotion:

Select the VM you want to move.
Click "Migrate" from the "Actions" menu.
Select the "Change storage only" option.
Select the target datastore.
Review the compatibility checks.
Complete the migration process.

Backing Up and Restoring VMs

Backing up VMs is important to prevent data loss. vCenter Server offers various options for backing up and restoring VMs. These include VMware vSphere Data Protection (VDP) and third-party backup solutions.

vSphere Data Protection (VDP):

Deploy and configure VDP in vCenter Server.
Select the VMs you want to back up.
Configure backup policies (e.g., backup frequency, retention period).
Start the backup jobs.

Restore:

Open VDP.
Select the VM and backup point you want to restore.
Configure restore options (e.g., restore to the original location or create a new VM).
Start the restore process.

Resource Management (CPU, Memory, Storage, Network)

Creating and Managing Resource Pools

Resource pools are used to group CPU and memory resources and share them among VMs. Resource pools help optimize resource utilization and improve the performance of VMs.

Open vSphere Client and log in to vCenter Server.
Select the host or cluster where you want to create a resource pool.
Click "New Resource Pool" from the "Actions" menu.
Give the resource pool a name and specify resource limits (for CPU and memory).
Add VMs to the resource pool.

Distributed Resource Scheduler (DRS) and High Availability (HA)

DRS helps balance resources and optimize performance by automatically moving VMs between ESXi hosts. HA provides high availability by automatically restarting VMs on another host when an ESXi host fails.

Enabling DRS:

Open vSphere Client and log in to vCenter Server.
Select the cluster.
Click the "Configure" tab.
In the "vSphere DRS" section, click "Edit".
Check the "Turn ON vSphere DRS" option.
Configure DRS settings (e.g., automation level, migration threshold).

Enabling HA:

Open vSphere Client and log in to vCenter Server.
Select the cluster.
Click the "Configure" tab.
In the "vSphere HA" section, click "Edit".
Check the "Turn ON vSphere HA" option.
Configure HA settings (e.g., host isolation response, VM restart priority).

Managing Storage Resources (Datastores, Storage Policies)

vCenter Server allows you to create, manage, and monitor datastores. You can also create storage policies to meet the storage requirements of VMs.

Creating a Datastore:

Open the vSphere Client and log in to vCenter Server.
Select the host or cluster.
Click the "Configure" tab.
In the "Storage" section, click "New Datastore".
Select the datastore type (e.g., VMFS, NFS).
Specify the datastore name and storage device.
Configure the datastore size and other settings.

Creating a Storage Policy:

Open the vSphere Client and log in to vCenter Server.
From the "Menu" menu, click "Policies and Profiles" -> "VM Storage Policies".
Click "Create VM Storage Policy".
Give the policy a name and specify the rules (e.g., RAID level, performance requirements).
Assign the policy to VMs.

Security Management

User and Role Management

vCenter Server allows you to manage users and roles. By assigning specific roles to users, you can control their access to the vSphere environment.

Open the vSphere Client and log in to vCenter Server.
From the "Menu" menu, click "Administration" -> "Users and Groups".
Create and manage users or groups.
In the "Roles" section, review predefined roles or create new roles.
Assign roles to users or groups (e.g., "Administrator", "Virtual Machine Power User", "Read Only").

Configuring Permissions

By configuring permissions, you can control the access of users or groups to specific objects in the vSphere environment (e.g., VMs, hosts, data centers).

Open the vSphere Client and log in to vCenter Server.
Select the object for which you want to configure permissions.
Click the "Permissions" tab.
Click "Add Permission".
Select the user or group.
Select the role.
Check "Propagate to child objects" to propagate the permissions (optional).

Certificate Management

vCenter Server allows you to manage certificates. Certificates are used to secure communication between components in the vSphere environment.

Open the vSphere Client and log in to vCenter Server.
From the "Menu" menu, click "Administration" -> "Certificate Management".
View, renew, or replace certificates.
To use custom certificates, upload certificates signed by a certificate authority (CA).

Real-Life Examples and Case Studies

Example 1: An e-commerce company manages multiple ESXi hosts using vCenter Server. Thanks to vCenter Server, the company can quickly deploy VMs, optimize resources, and provide high availability. The company ensures that its website and database servers are always accessible by using DRS and HA features.

Example 2: A financial institution protects its sensitive data using vCenter Server. vCenter Server offers security features such as user and role management, configuring permissions, and certificate management. The institution uses these features to prevent unauthorized access to the vSphere environment and ensure the security of its data.

Frequently Asked Questions (FAQ)

Q: Do I need vCenter Server?

A: If you are managing multiple ESXi hosts and need features such as central management, resource optimization, high availability, and security, then you need vCenter Server.

Q: How do I install vCenter Server?

A: You can install vCenter Server as vCenter Server Appliance (vCSA) or Windows-Based vCenter Server. vCSA is the deployment option recommended by VMware and is easier to install.

Q: How do I get a vCenter Server license?

A: You can purchase a vCenter Server license from VMware's website or from a VMware partner.

Q: How do I update vCenter Server?

A: You can update vCenter Server using Update Manager.

Q: How do I back up vCenter Server?

A: It is important to back up vCenter Server regularly. You can use VMware vSphere Data Protection (VDP) or third-party backup solutions to back up vCenter Server.

Conclusion and Summary

vCenter Server is a powerful and comprehensive tool for managing multiple ESXi hosts. Thanks to vCenter Server, you can centrally manage your virtualization infrastructure, optimize resources, provide high availability, and increase security. In this article, we examined in detail what vCenter Server is, its benefits, how to install it, how to configure it, and how to use it to manage multiple ESXi hosts. We hope this article has helped you understand and use vCenter Server.

Important Notes:

Planning: Before installing vCenter Server, ensure you meet the hardware and software requirements and plan the installation carefully.
Security: Configure vCenter Server securely and update it regularly.
Backup: Back up vCenter Server regularly.
Monitoring: Monitor vCenter Server and ESXi hosts regularly and detect problems early.
Documentation: Review VMware's official documentation and learn about the latest features and best practices of vCenter Server.

Custom Server Services

Standard Servers

Knowledge Base