By Crystal / Last Updated April 24, 2022

Why merge multiple VMDK files into a single one?

When you create a VM, there’s a step that lets you specify the disk capacity. Due to the limitation of FAT32, you may split virtual disk into multiple files to make each file smaller than 4 GB, and the split files will also be easier to move or copy.

disk space

However, multiple VMDK files may lead to poor performance of VM once they occupy large space of disk. To improve performance, you may want to merge multiple VMDK files into one disk.

In this article, I will explain how to merge VMDK files into one file in VMware Workstation, VMware Fusion or VMware Player, and introduce how to protect VMDK files efficiently.

How to merge multiple VMDK files into a single file

If you want to merge several VMDK files into a single VMDK file, you need to install Virtual Disk Manager (vmware-vdiskmanager) first. It is a utility that you can use it to create, manage, and modify virtual disk files from the command line.

You can use Virtual Disk Manager with virtual disks created under VMware Workstation 5 or higher, VMware Fusion, VMware Player, VMware ESX/ESXi server, etc.

Some of these platforms come with this file, while some do not have it. If you are using VMware Workstation or VMware Fusion, you can find it easily in your virtual machine software folder, but if you are using VMware Player, you can install this utility first in VMware website.

After ensuring you installed the vdiskmanager.exe, the remain steps are roughly the same. As examples, I will explain how to merge multiple VMDK files into one in some different situations.

vmware

Merge multiple VMDK files in VMware Workstation/Fusion

If you are using VMware Workstation or VMware Fusion, it is easy to access VMware-vdiskmanager and use it to merge source disks into a new single disk.

Steps to merge VMDK files:

1. Shut down the VM, and find the location of split VMDK files.

2. Find the VMware Workstation file and locate the vmware-vdiskmanager.exe on this folder, then do the following steps:

☛ Copy the path: C:\Program Files (x86)\VMware\VMware Workstation\vmware-vdiskmanager.exe

☛ Copy the source disk of VM: G:\Windows 10 x64.vmdk (original source file)

☛ Create a new destination folder for the new single file: G:\newimage\newimage.vmdk (destination file)

3. Open command prompt, then enter the command for example:

"C:\Program Files (x86)\VMware\VMware Workstation\vmware-vdiskmanager.exe" -r "G:\Windows 10 x64.vmdk" -t 0 "G:\newimage\newimage.vmdk"

converting multiple files

4. You can check the status, and the new single VMDK file will be created in the destination folder when it finishes to convert the multiple VMDK files.

a single vmdk file

5. After the new VMDK file is created, please move the original files into other directory, and rename the new VMDK file as the original one “Windows 10 x64.vmdk”

Now you finish the process to merge multiple VMDK files into a single file in Workstation. Please choose to use an existing virtual disk (using the new single VMDK file) to create a virtual machine.

use single vmdk file to create VM

Merge multiple VMDK files into one in VMware Player

If you are using VMware Player, you may find that VMware Player do not come with vdiskmanager. So, you should download it first in VMware website and refer to the following steps to combine VMDK files into one.

Steps to merge VMDK files:

1. Click here to start download vdiskmanager.

2. Unzip and rename 1023856-vdiskmanager-windows-7.0.1.exe into vmware-vdiskmanager.exe.

install vdiskmanager

3. Copy or move to the directory where VMware Player is installed.

⊹ If you see the denied notice while copying, click Continue.

⊹ After successful copy, right click the vdiskmanager >> Properties >> Unblock >> Apply.

vdiskmanager properties

4. Now, open the command prompt and enter this command as before:

☛"C:\Program Files (x86)\VMware\VMware Player\vmware-vdiskmanager.exe" -r  “C:\temp\Win2012R2\Windows Server 2012.mdk” -t 0 “C:\temp\Win2012R2_New\Win2012R2_New.vmdk”

converting vmdk files in vmware player

5. Then you will get a combined single VMDK file in VMware Player.

AOMEI Cyber Backup helps to back up VMDK files easily

Some of users may be confused about command line and worry about human errors to cause data-loss, so you should back up your important VM data before making big changes. Here, I will use a backup software call AOMEI Cyber Backup to eliminate these troubles.

AOMEI Cyber Backup provides flexible backup policies, automated backup, instant disaster recovery for you to create a powerful backup task which protects your virtual machine comprehensively.

1. Download AOMEI Cyber Backup and add source devices.

Download Free TrialVMware ESXi 6.0 & later versions
Secure Download

2. Create Backup Task: Select VMs >> Location >> Schedule Task >> Retention policy.

When preparing incremental backup, it compares to the existing full or incremental backup, only backs up the changed or newly added data. As a result, incremental backups require less time and storage space than full backups.

incremental backup ESXi

Tips: If you need to delete one of the full backups or one of the incremental backups, all the associated versions after this version need to be deleted.

Meanwhile, you can schedule your backup such as when to enable your backup task and how long you want to keep these backup files. It only keeps the newly and useful files as you set up, which saves storage space and reduces the extra cost.

vmware esxi backup

3. Click Restore to restore VM quickly in case of disaster and you are allowed to migrate the VM data to another host easily hitting Restore to new location.

VMware ESXi restore

The whole process is based on simple clicks that simplifies the VM management without installing agent or complicated operation.

With AOMEI Cyber Backup, you can get a high-performance virtual machine securely, and it saves disk space since this software offers automatic backup and retention policy to free up room. So, it will efficiently reduce your workload and save storage.

Frequently Asked Questions about VMDK file

Q: What happens if I delete VMDK files?

A: If you delete them, you will lose your VM data and corrupt your VM. Unless you have no longer need them, please do not delete them.

Q: How to split one VMDK file into several VMDK files?        

A: The procedures are similar to the former part, pay attention to changing -t 0 into -t 1.

Shut down the VM >> open a command prompt in Windows >> C:\Program Files (x86)\VMware\VMware Workstation\vmware-vdiskmanager.exe -r sourceDisk.vmdk -t 1 destinationDisk.vmdk

Summary

If you want to optimize the performance of your VM, I recommend you to follow these steps to merge VMDK files into a single one, and do not forget to back up your important data before merging VMDK.