Debugging the vmkernel.log file in VMware ESXi can be a crucial step in diagnosing and troubleshooting various issues. To facilitate this process, we can use PowerShell to fetch and filter log entries based on specific criteria. Below is a PowerShell script that helps in debugging the vmkernel.log:

# Connect to the ESXi host using SSH or other remote access methods
# Copy the vmkernel.log file from the ESXi host to a local directory
# Make sure to replace <ESXi_Host_IP> and <ESXi_Username> with appropriate values

$ESXiHost = "<ESXi_Host_IP>"
$ESXiUsername = "<ESXi_Username>"
$LocalDirectory = "C:\Temp\VMkernel_Logs"

# Create the local directory if it doesn't exist
if (-Not (Test-Path -Path $LocalDirectory -PathType Container)) {
    New-Item -ItemType Directory -Path $LocalDirectory | Out-Null
}

# Copy the vmkernel.log file to the local directory
$sourceFilePath = "/var/log/vmkernel.log"
$destinationFilePath = "$LocalDirectory\vmkernel.log"

Copy-VMHostLog -SourcePath $sourceFilePath -DestinationPath $destinationFilePath -VMHost $ESXiHost -User $ESXiUsername

# Read the contents of the vmkernel.log file and filter for specific keywords
$keywords = @("Error", "Warning", "Exception", "Failed", "Timed out")

$filteredLogEntries = Get-Content -Path $destinationFilePath | Where-Object { $_ -match ("({0})" -f ($keywords -join "|")) }

# Output the filtered log entries to the console
Write-Host "Filtered Log Entries:"
Write-Host $filteredLogEntries

# Alternatively, you can output the filtered log entries to a file
$filteredLogFilePath = "$LocalDirectory\Filtered_vmkernel_Log.txt"
$filteredLogEntries | Out-File -FilePath $filteredLogFilePath

Write-Host "Filtered log entries have been saved to: $filteredLogFilePath"

Before running the script, ensure you have the necessary SSH access to the ESXi host and the required permissions to read the vmkernel.log file. The script will copy the vmkernel.log file from the ESXi host to a local directory on your machine and then filter the log entries containing specific keywords such as “Error,” “Warning,” “Exception,” “Failed,” and “Timed out.” The filtered log entries will be displayed on the console and optionally saved to a file called “Filtered_vmkernel_Log.txt” in the specified local directory.

Please note that using SSH to access and copy log files from the ESXi host requires appropriate security measures and permissions. Be cautious when accessing sensitive log files and ensure you have proper authorization to access and analyze them.

Best Practices for Running SQL Servers on VMware:

1. Proper Resource Allocation: Allocate sufficient CPU, memory, and storage resources to the SQL Server VMs to ensure optimal performance and avoid resource contention.
2. Storage Performance: Use fast and low-latency storage systems for SQL Server VMs, and consider using vSphere features like VMware vSAN or Virtual Volumes (vVols) for better storage management.
3. vCPU Sizing: Size the vCPUs appropriately for SQL Server VMs. Avoid overcommitting CPU resources, and use multiple vCPU cores per socket for better performance.
4. Memory Reservations: Set memory reservations for critical SQL Server VMs to ensure they have guaranteed access to the required memory.
5. VMware Tools and VM Hardware Version: Keep VMware Tools up to date on SQL Server VMs and use the latest VM hardware version supported by your vSphere environment.
6. SQL Server Configuration: Configure SQL Server settings like max memory, parallelism, and tempdb appropriately to match the VM’s resources.
7. vMotion Considerations: Use vMotion carefully for SQL Server VMs to avoid performance impact during migration. Consider using CPU affinity and NUMA settings for large VMs.
8. Snapshots: Avoid using snapshots for long-term backups of SQL Server VMs, as they can lead to performance issues and disk space problems.
9. Monitoring and Performance Tuning: Use vSphere performance monitoring tools and SQL Server performance counters to identify and resolve performance bottlenecks.
10. Backup and Disaster Recovery: Implement a robust backup strategy for SQL Server databases, including both VM-level and database-level backups.
11. High Availability: Use SQL Server AlwaysOn Availability Groups or other clustering technologies for high availability and disaster recovery.
12. Security: Follow VMware security best practices and keep both the vSphere environment and SQL Server VMs patched and updated.
13. Network Configuration: Optimize network settings for SQL Server VMs, including network adapter type and network configurations.
14. Virtual Hardware Assist: Enable virtual hardware assist features like Virtualization-based security (VBS) and Virtual Machine Encryption for better security.
15. Database Maintenance: Regularly perform database maintenance tasks like index rebuilds and statistics updates to keep the SQL Server performance optimal.

PowerShell Script to Backup SQL Server Database:

To backup a SQL Server database using PowerShell, you can utilize the SqlServer module, which is part of the SQL Server Management Studio (SSMS) or the dbatools module, a popular community-driven module for database administration tasks. Below, I’ll provide examples for both approaches.

Using SqlServer Module:

Make sure you have the SqlServer module installed, which is available as part of the SQL Server Management Studio (SSMS). If you have SSMS installed, you should have the module.

# Connect to the SQL Server instance
$serverInstance = "<ServerName>"
$databaseName = "<DatabaseName>"
$backupFolder = "C:\Backups"

# Set the backup file name and path
$backupFileName = "$backupFolder\$databaseName-$(Get-Date -Format 'yyyyMMdd_HHmmss').bak"

# Perform the database backup
try {
    Invoke-Sqlcmd -ServerInstance $serverInstance -Database $databaseName -Query "BACKUP DATABASE $databaseName TO DISK='$backupFileName' WITH FORMAT, COMPRESSION"
    Write-Host "Database backup successful. Backup file: $backupFileName"
}
catch {
    Write-Host "Error occurred during database backup: $($_.Exception.Message)" -ForegroundColor Red
}

Replace <ServerName> and <DatabaseName> with your SQL Server instance name and the name of the database you want to back up. This script will create a full backup of the specified database in the provided $backupFolder location with a filename containing the database name and timestamp.

Using dbatools Module:

The dbatools module provides additional functionality and simplifies various database administration tasks. To use it, you need to install the module first.

# Install dbatools module (if not already installed)
Install-Module dbatools -Scope CurrentUser

# Import the dbatools module
Import-Module dbatools

# Connect to the SQL Server instance
$serverInstance = "<ServerName>"
$databaseName = "<DatabaseName>"
$backupFolder = "C:\Backups"

# Set the backup file name and path
$backupFileName = "$backupFolder\$databaseName-$(Get-Date -Format 'yyyyMMdd_HHmmss').bak"

# Perform the database backup
try {
    Backup-DbaDatabase -SqlInstance $serverInstance -Database $databaseName -Path $backupFileName -CopyOnly -CompressBackup
    Write-Host "Database backup successful. Backup file: $backupFileName"
}
catch {
    Write-Host "Error occurred during database backup: $($_.Exception.Message)" -ForegroundColor Red
}

This script will use the Backup-DbaDatabase cmdlet from the dbatools module to perform a full database backup with the CopyOnly and CompressBackup options. Again, replace <ServerName> and <DatabaseName> with your SQL Server instance name and the name of the database you want to back up.

Both scripts will create a full backup of the specified database with the current date and time appended to the backup file name. Make sure to adjust the $backupFolder variable to specify the desired backup location.

The scratch partition in VMware ESXi is used to store log files, VMkernel core dumps, and other diagnostic information. It is essential to configure the scratch partition properly for optimal performance and stability. Here are some best practices for configuring the scratch partition:

1. Dedicated Disk or LUN: Allocate a dedicated disk or LUN for the scratch partition. Avoid using the system disk or datastores where VMs are stored to prevent potential disk space contention.
2. Sufficient Size: Ensure that the scratch partition has sufficient space to store logs and core dumps. VMware recommends a minimum of 4GB, but depending on the number of hosts and log activity, a larger size might be necessary.
3. Non-Persistent Storage: Use non-persistent storage for the scratch partition. Avoid using storage that can be affected by VM snapshots or other data protection mechanisms.
4. Fast and Local Storage: Whenever possible, use fast and local storage for the scratch partition to minimize performance impact on other storage resources.
5. RAID Considerations: If using RAID, choose a RAID level that provides redundancy and performance suitable for your environment.
6. Network Isolation: If you configure the scratch partition to use a network file system (NFS) share, ensure that the network connection is reliable and provides adequate performance.
7. Regular Monitoring: Regularly monitor the scratch partition’s free space and archive or delete old log files to prevent running out of disk space.
8. Automate Configuration: Automate the configuration of the scratch partition during host deployments or using configuration management tools.

Finding Scratch Partitions using PowerShell:

In PowerShell, you can use VMware PowerCLI to find the scratch partition for all ESXi hosts. The scratch partition information is available in the ESXi advanced settings. Here’s how you can find it:

# Connect to the vCenter Server or ESXi hosts
Connect-VIServer -Server <vCenter_Server_or_ESXi_Host> -User <Username> -Password <Password>

# Get a list of all ESXi hosts
$esxiHosts = Get-VMHost

# Loop through each host and retrieve the scratch partition setting
foreach ($host in $esxiHosts) {
    $scratchPartition = Get-AdvancedSetting -Entity $host -Name "ScratchConfig.ConfiguredScratchLocation"
    Write-Host "ESXi Host: $($host.Name) - Scratch Partition: $($scratchPartition.Value)"
}

# Disconnect from the vCenter Server or ESXi hosts
Disconnect-VIServer -Server <vCenter_Server_or_ESXi_Host> -Confirm:$false

The above PowerShell script will display the names of all ESXi hosts and their corresponding scratch partition settings.

Finding Scratch Partitions using Python:

To find the scratch partition using Python, you can use the pyVmomi library, which is the Python SDK for VMware vSphere. First, make sure you have pyVmomi installed:

pip install pyVmomi

Now, you can use the following Python script:

from pyVmomi import vim
from pyVim.connect import SmartConnect, Disconnect
import ssl

# Ignore SSL certificate verification (only needed if using self-signed certificates)
context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
context.verify_mode = ssl.CERT_NONE

# Connect to the vCenter Server or ESXi hosts
si = SmartConnect(host="<vCenter_Server_or_ESXi_Host>",
                  user="<Username>",
                  pwd="<Password>",
                  sslContext=context)

# Get a list of all ESXi hosts
content = si.RetrieveContent()
container = content.viewManager.CreateContainerView(content.rootFolder, [vim.HostSystem], True)
esxiHosts = container.view

# Loop through each host and retrieve the scratch partition setting
for host in esxiHosts:
    for option in host.config.option:
        if option.key == "ScratchConfig.ConfiguredScratchLocation":
            print("ESXi Host: {} - Scratch Partition: {}".format(host.name, option.value))

# Disconnect from the vCenter Server or ESXi hosts
Disconnect(si)

The Python script will display the names of all ESXi hosts and their corresponding scratch partition settings.

With these PowerShell and Python scripts, you can efficiently find the scratch partitions for all ESXi hosts in your vSphere environment and ensure they are properly configured based on best practices.

Validating high compute usage by hosts and virtual machines (VMs) is important for ensuring the health and performance of your VMware vSphere environment. Esxtop is a powerful command-line utility that provides real-time performance monitoring of ESXi hosts, while PowerShell with VMware PowerCLI allows you to automate data collection and output the results to a file for further analysis. In this guide, we’ll walk through the steps to use esxtop and PowerShell to monitor compute usage and save the data to a file.

1. Using Esxtop to Monitor Compute Usage:

Esxtop provides detailed performance metrics for CPU, memory, storage, network, and other system resources. To monitor CPU usage with esxtop:

• SSH into your ESXi host using a terminal client.
• Launch esxtop by typing esxtop and pressing Enter.
• Press the ‘c’ key to switch to the CPU view.
• Observe the CPU performance metrics, including %USED, %IDLE, %WAIT, %READY, %CSTP, etc.
• Press ‘q’ to exit esxtop.

2. Using PowerShell and PowerCLI:

PowerCLI is a PowerShell module for managing and automating VMware vSphere environments. We’ll use it to extract CPU usage information from ESXi hosts and VMs and save the data to a file.

Step 1: Install PowerCLI: If you haven’t installed PowerCLI, download and install it from the PowerShell Gallery using the following command:

Install-Module VMware.PowerCLI -Force

Step 2: Connect to vCenter Server or ESXi Host:

Connect-VIServer -Server <vCenter_Server_or_ESXi_Host> -User <Username> -Password <Password>

Step 3: Get Host CPU Usage:

# Get the ESXi hosts
$hosts = Get-VMHost

# Create an array to store CPU usage data
$cpuData = @()

# Loop through each host and retrieve CPU usage data
foreach ($host in $hosts) {
    $cpuUsage = Get-Stat -Entity $host -Stat cpu.usage.average -Realtime -MaxSamples 1 | Select-Object @{Name = "Host"; Expression = {$_.Entity.Name}}, Value, Timestamp
    $cpuData += $cpuUsage
}

# Export the data to a CSV file
$cpuData | Export-Csv -Path "C:\Temp\Host_CPU_Usage.csv" -NoTypeInformation

Step 4: Get VM CPU Usage:

# Get the VMs
$VMs = Get-VM

# Create an array to store CPU usage data
$cpuData = @()

# Loop through each VM and retrieve CPU usage data
foreach ($VM in $VMs) {
    $cpuUsage = Get-Stat -Entity $VM -Stat cpu.usage.average -Realtime -MaxSamples 1 | Select-Object @{Name = "VM"; Expression = {$_.Entity.Name}}, Value, Timestamp
    $cpuData += $cpuUsage
}

# Export the data to a CSV file
$cpuData | Export-Csv -Path "C:\Temp\VM_CPU_Usage.csv" -NoTypeInformation

Step 5: Disconnect from vCenter Server or ESXi Host:

Disconnect-VIServer -Server <vCenter_Server_or_ESXi_Host> -Confirm:$false

By running the PowerShell scripts above, you will retrieve CPU usage data for both the ESXi hosts and VMs and save it to CSV files named “Host_CPU_Usage.csv” and “VM_CPU_Usage.csv” in the “C:\Temp” directory (you can change the file paths as needed). The CSV files can then be opened with tools like Microsoft Excel for further analysis.

Please note that the examples provided above focus on CPU usage, but you can modify the scripts to gather data for other performance metrics, such as memory, storage, or network usage, by changing the -Stat parameter in the Get-Stat cmdlets.

In conclusion, using esxtop and PowerShell with PowerCLI, you can effectively monitor and validate high compute usage by ESXi hosts and VMs, and save the data to files for in-depth analysis and performance optimization in your VMware vSphere environment.

In VMware vSphere, the Set-AdvancedSetting cmdlet in VMware PowerCLI is used to modify advanced settings of a vSphere object, such as an ESXi host, a virtual machine (VM), a vCenter Server, or other vSphere components. These advanced settings are typically configuration parameters that control specific behaviors or features of the vSphere environment. It’s essential to use this cmdlet with caution, as modifying advanced settings can have a significant impact on the system’s behavior and stability.

The syntax for the Set-AdvancedSetting cmdlet is as follows:

Set-AdvancedSetting -Entity <Entity> -Name <SettingName> -Value <SettingValue>

• <Entity>: Specifies the vSphere object to which the advanced setting should be applied. This can be an ESXi host, a VM, or any other vSphere entity that supports advanced settings.
• <SettingName>: Specifies the name of the advanced setting that you want to modify.
• <SettingValue>: Specifies the new value to be set for the advanced setting.

Please note that the -Entity parameter is mandatory, while the -Name and -Value parameters are used to specify the advanced setting to modify and its new value, respectively.

Here’s an example of using Set-AdvancedSetting to modify an advanced setting on an ESXi host:

# Connect to the vCenter Server or ESXi host
Connect-VIServer -Server <vCenter_Server_or_ESXi_Host> -User <Username> -Password <Password>

# Get the ESXi host object
$esxiHost = Get-VMHost -Name <ESXi_Host_Name>

# Set a specific advanced setting on the ESXi host
Set-AdvancedSetting -Entity $esxiHost -Name "Net.ReversePathFwdCheckPromisc" -Value 1

# Disconnect from the vCenter Server or ESXi host
Disconnect-VIServer -Server <vCenter_Server_or_ESXi_Host> -Confirm:$false

In this example, we are modifying the Net.ReversePathFwdCheckPromisc advanced setting on the specified ESXi host to set its value to 1.

Please remember that modifying advanced settings should be done with caution, as incorrect values or misconfigurations can lead to system instability or undesirable behavior. Always refer to VMware documentation or consult with experienced VMware administrators before modifying advanced settings in your vSphere environment. Additionally, take appropriate backups or snapshots of critical components before making any changes to revert back to the original configuration if needed.