Fetching vCenter Performance Statistics with PowerCLI: A Step-by-Step Guide

Understanding the performance of your VMware vSphere environment is crucial for maintaining a healthy and efficient infrastructure. While vCenter Server provides various built-in performance charts, leveraging PowerCLI allows for powerful automation, custom reporting, and historical data analysis that goes beyond the standard GUI.

This guide will walk you through the process of using PowerCLI to fetch vCenter performance statistics, providing step-by-step instructions and illustrative examples.

What is PowerCLI?

PowerCLI is a command-line interface and PowerShell module developed by VMware for managing and automating vSphere. It provides a rich set of cmdlets (command-lets) that allow you to interact with almost every aspect of your vCenter and ESXi hosts.

Why use PowerCLI for Performance Statistics?

• Automation: Automate the collection of performance data on a schedule.

• Custom Reporting: Generate custom reports tailored to your specific needs.

• Historical Data Analysis: Easily retrieve and analyze historical performance data over long periods.

• Integration: Integrate performance data with other tools and scripts.

• Efficiency: Fetch large amounts of data more efficiently than manual GUI navigation.

Prerequisites

Before you begin, ensure you have the following:

1. PowerShell: Installed on your workstation.

2. PowerCLI: Installed on your workstation. If not, open PowerShell and run:

   PowerShell

   Install-Module -Name VMware.PowerCLI
   

   You might need to adjust your PowerShell execution policy if you encounter errors:

   PowerShell

   Set-ExecutionPolicy RemoteSigned
   

3. vCenter Server: Access to a vCenter Server instance with appropriate credentials.

Step 1: Connect to your vCenter Server

The first step is to establish a connection to your vCenter Server. You’ll use the Connect-VIServer cmdlet for this.

Connect-VIServer -Server your_vcenter_server_ip_or_hostname -User your_username -Password your_password

Example:

Connect-VIServer -Server vcenter.example.com -User administrator@vsphere.local -Password MyStrongPassword!

Note: For security best practices, avoid hardcoding passwords directly in your scripts. Consider using Get-Credential for interactive password prompts or secure credential storage.

Step 2: Identify Performance Metrics

Before fetching data, you need to know which performance metrics are available and their corresponding IDs. The Get-StatType cmdlet helps with this.

Get-StatType -Entity (Get-VM "YourVMName")

This command will list all available performance metrics for a specific VM. If you omit -Entity, it will list all available metrics across your vCenter, which can be a very long list.

Example: Listing metrics for a VM

Get-StatType -Entity (Get-VM "Web_Server_01")

You’ll see output similar to this, showing the metric name, group, and other details. Pay attention to the Key column, which is the metric ID you’ll use later.

Get-StatType | Select-Object Group, Name, Key, Unit | Format-Table -AutoSize

Get-Stat -Entity <VMware.VimAutomation.ViCore.Impl.V1.Inventory.InventoryItemImpl> -Stat <String[]> -IntervalMins <Int32> -Start <DateTime> -Finish <DateTime>

$vm = Get-VM "Web_Server_01"
$startTime = (Get-Date).AddHours(-1)
$endTime = Get-Date

Get-Stat -Entity $vm -Stat "cpu.usage.average", "mem.usage.average" -IntervalMins 5 -Start $startTime -Finish $endTime |
    Select-Object MetricId, Timestamp, Value, Unit |
    Format-Table -AutoSize

$host = Get-VMHost "esxi-host-01.example.com"
$vms = Get-VM -Location $host
$startTime = (Get-Date).AddDays(-7) # Last 7 days
$endTime = Get-Date

Get-Stat -Entity $vms -Stat "net.usage.average" -IntervalMins 30 -Start $startTime -Finish $endTime |
    Select-Object Entity, MetricId, Timestamp, Value, Unit |
    Sort-Object Entity, Timestamp |
    Format-Table -AutoSize