Understanding the "Failed to Read from File VMDK" Error

Virtual Machines (VMs) function much like physical computers, offering similar computational capabilities, yet they exist entirely in the digital realm and cannot be physically interacted with. When encountering an error while launching a VM, it's often due to missing or corrupted files associated with the VM. These issues typically arise when the VM cannot access or read the VMDK file, which acts as a virtual hard drive, or when the VM exhausts its allotted storage space. Understanding and resolving these challenges is crucial for maintaining seamless virtual operations. This article delves deep into diagnosing and addressing such errors, guiding you through practical solutions to ensure your VM operates smoothly. We will explore techniques to recover corrupted files, steps to reallocate space efficiently, and general tips to prevent future occurrences. Whether you're a seasoned professional managing multiple VMs or a newcomer navigating virtual environments, this guide aims to equip you with the necessary insights to troubleshoot and resolve common VM launch issues effectively.

Common Causes of the VMDK Read Error

Some common reasons why VMDK files may become inaccessible are explained below:

Corrupted VMDK Files

Malware or virus attacks on the computer can lead to corrupt VMDK files, which then make the file inaccessible. Also, VMDK files have an embedded –flat.vmdk file, the –flat.vmdk file may be the corrupted one, and if that is the scenario, then you need to roll back the VM to an old state using snapshots or local backup.

Disk Space Issues

Of course, if your disk storage space is totally exhausted, not only your VMs, but the system would generally turn sluggish and degrade in performance. However, in the case of VMs, exhausted storage space could cause the VM not to turn on.

File Permission Problems

If you migrated the VM to another host or system, probably, you didn’t set the permissions right or didn’t set them at all. Check the permissions required for your VM to run smoothly on the new host or system; in most cases, this is simply the issue.

Network Connectivity Issues

Check your network connections and IP addresses to confirm that your VM’s network settings are fully and correctly configured. Misconfigured network settings can cause VM inaccessibility issues because the system cannot communicate with the peripherals.

Diagnosing the Issue

When your VM throws an error message, the first thing to do is to figure out what could have triggered the error, and this can be achieved by troubleshooting the VM.

Checking VMware Logs

You should check the log files to see if you can trace the issue. Most VMware logs files are stored in the following path in Windows computers, C:\ProgramData\VMware\vCenterServer\Logs. You can also check your VM’s folder for any .log file type.

Using VMware vSphere Client

Log in to your vSphere Client interface and go to the datastores section; check if the datastore you connected to your VM during the creation time is still there and is accessible. If the datastore is missing, that is the culprit, you need to troubleshoot and recover the missing datastore to launch your VM.

Verifying Disk Space and Permissions

If you used fixed VMDK when creating the VM, verify if the virtual disk still has free space. If you were using dynamic VMDK, make sure you still have free space on your physical storage disk. While verifying the disk space, you should also check the storage permissions for your VM.

Tip: how to install VMware tools on Ubuntu

Solutions to Fix the VMDK Read Error

Need to recover VMware virtual machine? These tips will help you fix the VMDK read error, you should try them one after another. If you can, make a backup before carrying on with these workarounds.

Restoring from Backup

If corrupted VMDK, or most files in your VM local folder are missing, the best solution is to recover from a backup you must have created earlier. So to say, if you didn’t make any prior backup, this isn’t the method you should try. Recovering your files from backup depends on the backup application you used – if you backed up to a cloud storage, you need an active internet connection to recover the file. Learn more on how to restore VMDK from backup.

Repairing the VMDK File

To repair a corrupt VMDK file, you need a professional tool that allows for such. Basically, some VMDK recovery software programs have the capability to repair corrupt VMDK files during the recovery process. The DiskInternals VMFS Recovery program can repair corrupt VMDK files during the recovery scan process.

DiskInternals VMFS Recovery is a professional Windows OS program that supports the native VMware file system format – VMFS. This software comes with an intuitive interface and can repair corrupt VMware virtual machine files. If you don’t want to use a third-party tool, there are built-in VMware tools that allow you to attempt corrupt file repairs.

Using VMware’s Built-in Tools

You can install VMware's Virtual Disk Development Kit (VDDK) in the same directory your VMware products and files are saved. The VDDK is a VMware utility tool that combines several APIs and tools for repairing corrupt VMDK files and dealing with other common VMware VM issues.

Using DiskInternals VMFS Recovery

The friendly UI of DiskInternals VMFS Recovery makes it easy for everyone to be able to use the software. It equally integrates a Wizard that launches automatically as launch the program. This software can be used to fix most VMware VM issues such as VMFS partition read error, corrupted VMware boot image, missing or hidden ESX Server datastore, problems with mounting the VMFS volume, and many others.

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Compatible with

Using DiskInternals VMFS Recovery, you can repair corrupted VMDK file, as well as recover any lost/deleted VM data or file you thought was gone forever. This software supports the VMFS format along with other known Windows and Linux OS file systems. You can launch DiskInternals VMFS Recovery remotely by connecting to your ESXi host via SSH.

Addressing Disk Space and Permission Issues

Check the permissions assigned to the user profile you’re using to access the VM. A user’s activity on a virtual machine is dependent on the level of permissions assigned to the user account. Unless you’re using an admin account and getting the “Failed to read…” error, chances are that the user account you logged in with doesn’t have sufficient permissions to carry out the task you want to perform or access the file you’re trying to read.

Notwithstanding, insufficient storage space can cause file read issues on a VM; you should check the remaining free space on your virtual hard disk and expand it (if needed).

Ensuring Stable Network Connectivity

Network connectivity issues might be the reason your VM is not reading the files you want to access. To troubleshoot and fix this, you must look into the vSwitches and network cables used on the host system. Ensure that the Port Group name(s) of your VM exists and corresponds with the VM’s network adapter, whether you’re using VDS (Virtual Distributed Switches) or VSS (Virtual Standard Switches).

But, if you’re using VSS vSwitch, the connected VM cannot be placed on a vmkernel port group because standard switches require you to create a port group for each vmkernel. To view and manage vSwitches, log into your VMware Host Client or vSphere Client and navigate to the vSwitch section.

Preventative Measures

To always be on the safe side and make sure you’re not thrown off balance in data loss scenarios, here are some useful tips you should adhere to.

Make Regular Backups

This cannot be overemphasized; anyone who runs one or more VMs needs to make regular onsite and offsite backups. Onsite backups here can refer to snapshots, while offsite backups may refer to saving a copy of your VM data on external storage devices such as cloud storage platforms and external HDDs.

Monitoring Disk Space

Always keep an eye on your disk space; both the virtual storage and primary physical storage. No system performs smoothly when the storage space is full or almost full. Delete older snapshots from time to time to save up your virtual space and defragment your physical storage to clear off junk files.

Ensuring Proper Permissions

When creating new users on VM, ensure to assign the full permissions you want for the user. As the admin user, during the VM creation stages and initial configurations, assign all required permissions to gain access to all actions on the VM.

Network Reliability Checks

Always cross check the IP address and switches you’re using for your VM. Run prechecks to confirm the network connections you’re configuring for your machines. Seamless network connections is what’s needed for swift communication between your VMs and the system resources it is using.

Tip: VM backup vs snapshot

Conclusion

VM errors are usually due to VMDK or network connection issues. Of course, there are other things that could cause a VM not to launch, but these are the two most common causes. Always look into your logs to diagnose what could be the issue with your VM. However, you can use third-party software tools to repair your corrupt VM files or recover any lost one.