Introduction to vmkfstools

vmkfstools is a versatile tool used for creating, managing, and maintaining VMware ESX/ESXi virtual machine file systems and virtual disks. It’s primarily used for tasks like creating and cloning virtual disks, managing VMFS volumes, and repairing and expanding disks.

Key Features of vmkfstools

• Disk Management: Create, clone, and extend virtual disk files.

• VMFS Management: Create, extend, and upgrade VMFS volumes.

• Disk Inspection and Repair: Check the integrity of virtual disks and repair them if necessary.

• Snapshot Handling: Manage snapshots by creating and deleting virtual disk snapshots.

Getting Started with vmkfstools

Before diving into complex tasks, it’s crucial to understand the basic syntax of the vmkfstools command:

vmkfstools [options] <virtual disk or VMFS path>

Common Options in vmkfstools

• -c (create a new virtual disk)

• -d (disk format, such as thin or thick)

• -E (rename a disk)

• -i (clone a disk)

• -q (display disk details)

• -X (extend the size of a disk)

• -r (recover a snapshot)

• -v (verbose mode)

Examples of Using vmkfstools

1. Creating a Virtual Disk

To create a new 10 GB virtual disk in thin provisioning format:

vmkfstools -c 10G -d thin /vmfs/volumes/datastore1/newDisk.vmdk

2. Cloning a Virtual Disk

To clone an existing virtual disk to a new disk:

vmkfstools -i /vmfs/volumes/datastore1/oldDisk.vmdk /vmfs/volumes/datastore1/clonedDisk.vmdk

3. Extending a Virtual Disk

To extend a virtual disk to 20 GB:

vmkfstools -X 20G /vmfs/volumes/datastore1/extendDisk.vmdk

4. Renaming a Virtual Disk

To rename a virtual disk:

vmkfstools -E /vmfs/volumes/datastore1/oldName.vmdk /vmfs/volumes/datastore1/newName.vmdk

Advanced Use-Cases

• Managing Snapshots: How to create and manage snapshots using vmkfstools.

• VMFS Volume Management: Detailed steps to create, expand, and manage VMFS volumes.

• Repairing Virtual Disks: How to check and repair corrupted virtual disks.

Best Practices

• Regular Backups: Always ensure backups are taken before performing operations that modify disk data.

• Monitoring and Maintenance: Regularly check disk integrity and VMFS health to avoid data corruption and ensure performance.

Troubleshooting Common Issues

• Disk Size Issues: Solutions for when disks do not resize as expected.

• Performance Optimization: Tips for optimizing the performance of virtual disks and VMFS volumes.

vmkfstools is not directly executable via VMware PowerCLI or Windows PowerShell due to its nature as an ESXi command-line tool, administrators often need to perform tasks that involve vmkfstools for managing VMFS volumes or virtual disks. Here, I will outline how you can utilize PowerCLI along with remote SSH commands to execute vmkfstools tasks from a PowerShell environment.

Script Purpose

This script example demonstrates how you can use VMware PowerCLI to manage ESXi hosts and then use SSH to execute vmkfstools commands on those hosts. This approach combines the power of PowerCLI for overall VMware management with the specific capabilities of vmkfstools.

Prerequisites

• PowerShell 5.1 or higher

• VMware PowerCLI installed

• SSH client enabled on the ESXi host

• Credentials and permissions to manage the ESXi host

PowerShell Script Example

# Import VMware PowerCLI modules
Import-Module VMware.PowerCLI

# Connect to vCenter
$vcServer = "your_vcenter_server"
$vcUser = "your_username"
$vcPass = "your_password"
Connect-VIServer -Server $vcServer -User $vcUser -Password $vcPass

# Specify the ESXi host and credentials for SSH
$esxiHost = "esxi_host_ip"
$username = "root"
$password = "your_esxi_password"  # It's safer to use secure password handling

# Load the Posh-SSH module for SSH functionality
Import-Module Posh-SSH

# Establish SSH Session to the ESXi host
$sshSession = New-SSHSession -ComputerName $esxiHost -Credential (New-Object System.Management.Automation.PSCredential($username, (ConvertTo-SecureString $password -AsPlainText -Force)))

# vmkfstools command to create a new virtual disk
$newDiskCommand = "vmkfstools -c 10G -d thin /vmfs/volumes/datastore1/newDisk.vmdk"
$newDiskResult = Invoke-SSHCommand -SessionId $sshSession.SessionId -Command $newDiskCommand
Write-Output "Output of creating new disk: $($newDiskResult.Output)"

# vmkfstools command to clone an existing virtual disk
$cloneDiskCommand = "vmkfstools -i /vmfs/volumes/datastore1/existingDisk.vmdk /vmfs/volumes/datastore1/clonedDisk.vmdk -d thin"
$cloneDiskResult = Invoke-SSHCommand -SessionId $sshSession.SessionId -Command $cloneDiskCommand
Write-Output "Output of cloning disk: $($cloneDiskResult.Output)"

# Properly disconnect the SSH session
Remove-SSHSession -SessionId $sshSession.SessionId

# Disconnect from vCenter
Disconnect-VIServer -Server $vcServer -Confirm:$false

Explanation of Script Commands

• Connect-VIServer: Establishes a connection to the vCenter server to manage the VMware infrastructure.

• New-SSHSession: Opens an SSH session to the ESXi host to execute vmkfstools commands. Credentials are passed securely.

• Invoke-SSHCommand: Sends a command via SSH to be executed on the ESXi host. Here, it runs vmkfstools to create and clone virtual disks.

• Remove-SSHSession and Disconnect-VIServer: Clean up the sessions by closing the SSH and vCenter connections, ensuring no open sessions are left.