Migrating VMFS 5 Datastore to VMFS 6 Datastore

You can actually have VMFS 5 and VMFS 6 datastores existing in the same ESXi host, but since VMFS 6 is the latest version, it is always advisable to migrate from VMFS 5 if you’re still using it. However, migrating datastores is a technical action, and as such, you should make full backups of your VMs on the VMFS 5 datastore before making the move to a VMFS 6 datastore.

In addition to making full backups of your VMs, you should pay keen attention to the procedures explained in this article; not following the procedures carefully may lead to losing some of your VM’s important files. This article details how to move your VMs from a VMFS 5 datastore to a VMFS 6 datastore without losing any files.

Why Upgrade to VMFS 6?

VMFS 5 is actually good and offers a ton of handy features, but VMFS 6 starts from where the VMFS 5 stops. Both VMFS versions have the same storage features, but the VMFS 6 goes on to support automatic space reclamation and 512n storage devices by default, while also adopting SESparse as the default snapshot technology.

VMFS 5 supports SEsparse for snapshots, but only for larger disks – for smaller disks, the default is VMFSsparse. More so, upgrading to VMFS 6 means you’re using a VMFS version that would still be actively supported for a couple of years more than VMFS 5. Finally, VMFS 6 can guarantee better performance and stability.

Upgrading to VMFS 6 offers several advantages over VMFS 5, enhancing both performance and functionality. Here are the key reasons to upgrade:

1. Performance Improvements:
- 64TB File Size Support: VMFS 6 supports larger single file sizes, which is particularly beneficial for large virtual machines and applications that require extensive storage.
- Automatic Space Reclamation: The SE Sparse disks feature allows for automatic space reclamation, which helps to maintain efficient storage usage and reduces the need for manual interventions.
2. Enhanced Storage Efficiency:
- Advanced Block Sizes: VMFS 6 introduces support for 1MB and 512MB block sizes, offering more efficient space utilization and better performance for both small and large files.
- Automatic UNMAP: This feature helps to reclaim unused storage space automatically, improving overall storage efficiency and reducing wasted space.
3. Improved Resiliency and Reliability:
- Optimized for Modern Storage Arrays: VMFS 6 is designed to work seamlessly with modern storage arrays, providing better integration and performance.
- Improved Locking Mechanism: The new ATS (Atomic Test and Set) locking mechanism enhances the reliability and performance of shared storage environments.
4. Security Enhancements:
- Encryption Support: VMFS 6 supports encryption at the datastore level, providing an additional layer of security for your data.
5. Future-Proofing:
- Support for Latest VMware Features: Upgrading to VMFS 6 ensures compatibility with the latest VMware features and updates, keeping your infrastructure up-to-date with the newest advancements in virtualization technology.

By upgrading to VMFS 6, you can take advantage of these enhancements to optimize your virtual environment, improve performance, and ensure better storage management and security.

How to Migrate VMFS 5 to VMFS 6

The quick summary of the migration process is to create a blank VMFS 6 datastore and then migrate your VMs from an old VMFS 5 data to the new VMFS 6. Yes, it sounds pretty simple like that, but the steps are quite technique and require prompt carefulness.

1. Create a New VMFS 6 Datastore

While logged into your vSphere Client, go to Storage 🡺 New Datastore 🡺and select VMFS datastore.
Choose a name for your new datastore to make it unique, then set a directory to save the datastore.
Select a new device to use for your data store. (Note: this new device must not be connected to any other datastore, which means it should have no entry in the Snapshot Volume column).
Select VMFS 6 as the datastore version.
Review your selections and finish the creation.

Note: Ensure to assign the same amount of storage space (or even more) as on the VMFS 5 to the new VMFS 6.

2. Preparing To Transfer Your VMs

Migrating from VMFS 5 to VMFS 6 follows the same process, but the steps may differ based on the scenario at hand. But then, here are some prerequisites to keep in mind:

Identify the exact VMFS 5 you need to upgrade, let’s say the name is DSTR-1.
Identify the vCenter Server and point out all ESX hosts sharing the datastore.
Before the migration, ensure that all your ESX hosts and the vCenter server are running on vSphere 6.5. Any ESX host that is not on vSphere 6.5 will lose connection to the new VMFS 6 datastore after the upgrade.

MOST IMPORTANTLY: Run a complete backup of your VMs before making the migrations; just in case things go south and you need to restore from a good point.

3. Migrating VMFS 5 Datastore to VMFS 6

Let’s assume that you have one vCenter Server appliance with a registered VM running on DSTR-1 (the VMFS 5 datastore) and you need to migrate the datastore to VMFS 6, here’s how to go about it.

Step One: Crosscheck the vCenter Server and all hosts attached to it to ensure they are running vSphere 6.5.
Step Two: The new VMFS 6 datastore you’re migrating to must have the same storage space as the VMFS 5 you’re migrating from.
Step Three: Make a list of all VMs on the DSTR-1 datastore; you have to move them individually to avoid loss of data.
Step Four: Use storage vMotion to evacuate all the VMs on DSTR-1, one VM at a time.
Right-click the each you want to evacuate and select Migrate.
Following the migration wizard pop-up, select Change storage only.
Now migrate to an “alternative” datastore

Note: Monitor the migration process, if any VM is unable to migrate successfully, note it down and re-trigger the migration afterward.

Step Five: After evacuating all your VMs, run a check to confirm that DSTR-1 is now empty before proceeding with the next step.
Step Six: Unmount DSTR-1 from all connected ESX hosts, and then delete it.
Step Seven: Create a new VMFS 6 datastore using the same LUN as the old datastore you just deleted.

Step Eight: Configure the new datastore, then move all your migrated VMs (from the alternative datastore) to this “new” datastore using storage vMotion, move them one at a time.

4. Post-Migration Validation:

Verify Data Integrity: After migration, perform thorough checks to ensure data integrity. This includes verifying that all files and virtual machines are accessible and functioning correctly.
Check VM Functionality: Power on and test each virtual machine to confirm that they are running as expected without any errors or data corruption.
Compare Checksums: Use checksum tools to compare the integrity of files before and after migration. This helps to confirm that no data has been altered or corrupted during the process.

5. Documentation and Reporting:

Document the Process: Keep detailed records of the migration process, including any issues encountered and how they were resolved. This documentation will be valuable for future migrations and troubleshooting.
Report Findings: Share the results of the post-migration validation with stakeholders, highlighting the success of the migration and any areas that may need further attention.

6. Regular Monitoring and Maintenance:

Monitor Performance: Continuously monitor the performance of the new VMFS 6 datastore to ensure it meets expected performance levels.
Schedule Regular Backups: Maintain a regular backup schedule to protect against future data loss and ensure ongoing data integrity.

Note: VMFS5 vs VMFS6

Testing and Optimization

After you have moved all your VMs to the new VMFS 6 datastore, you should test the VMs and ensure that all of them are accessible and your ESX hosts are functional. If you need to optimize your VMs for better performance and to adjust to VMFS 6 settings, you can do that on the settings panel on the vSphere vCenter appliance.

Validating functionality and performance

Functionality Checks:

Power-On Tests: After migration, power on all virtual machines (VMs) to ensure they start without issues. Check for any boot errors or system crashes.
Application Testing: Verify that applications running within the VMs function correctly. This includes checking for errors, crashes, and performance issues in critical applications.
Data Integrity: Ensure that all data within the VMs is intact. Compare pre- and post-migration data to confirm there is no corruption or loss.

Performance Testing:

Baseline Comparison: Measure performance metrics such as CPU, memory, and I/O performance before and after migration to compare and ensure there is no degradation.
Benchmarking Tools: Use benchmarking tools like VMware’s vBenchmark, Iometer, or other performance testing software to evaluate the performance of the migrated VMs.
Load Testing: Conduct load tests to simulate real-world usage and observe how the system handles peak loads. This helps identify any performance bottlenecks or issues.
Latency and Throughput: Monitor latency and throughput of the storage system to ensure it meets the expected performance levels. Tools like esxtop or vRealize Operations can be useful for this.

User Feedback:

Collect Feedback: Engage with end-users to gather feedback on system performance and functionality post-migration. End-user feedback can help identify issues that automated tests may miss.
Issue Tracking: Use an issue tracking system to document and address any problems reported by users. This helps in resolving issues systematically and improving overall performance.

Optimizing VMFS 6 features

Automatic Space Reclamation:

Enable UNMAP: Ensure that the UNMAP feature is enabled to automatically reclaim unused storage space. This can be done through the vSphere Web Client or PowerCLI.
Configure UNMAP Frequency: Adjust the frequency of the UNMAP process to balance performance and storage efficiency based on your specific workload requirements.

Advanced Block Sizes:

Select Appropriate Block Sizes: VMFS 6 supports 1MB and 512MB block sizes. Choose the block size that best suits your workload. For example, larger block sizes may be more efficient for large files and databases, while smaller block sizes can be better for environments with many small files.
Optimize Based on Usage: Analyze the types of files and applications you are running and optimize the block size settings accordingly to ensure optimal performance and storage utilization.

Storage Policies:

Create Storage Policies: Leverage VMFS 6 storage policies to define and manage storage capabilities such as encryption, IOPS limits, and redundancy. These policies help ensure that VMs are placed on the appropriate storage with the right performance and security characteristics.
Apply Policies Consistently: Ensure that storage policies are consistently applied to all relevant VMs and datastores to maintain uniform performance and security standards.

Regular Maintenance:

Defragmentation: Schedule regular defragmentation tasks to improve the performance and efficiency of the datastore. This helps in reorganizing fragmented data and can lead to better I/O performance.
Space Reclamation: Perform periodic space reclamation to ensure that the datastore remains optimized. This can be done using VMware’s native tools or third-party solutions that support space reclamation.
Monitoring and Alerts: Set up monitoring and alerts to track the health and performance of the VMFS 6 datastore. Use tools like vRealize Operations to get insights into storage usage and performance trends.

Performance Tuning:

Adjust Queue Depths: Optimize storage performance by adjusting the queue depths for your storage adapters. This can help balance the load and prevent bottlenecks.
Storage Multipathing: Configure multipathing to improve redundancy and performance. Ensure that the multipathing policy is set correctly based on your storage array’s recommendations.

Security Enhancements:

Enable Datastore Encryption: Use VMFS 6’s encryption feature to protect sensitive data at rest. Configure encryption through vSphere and ensure that encryption keys are managed securely.
Access Control: Implement strict access control measures to limit who can modify or access the datastore. Use roles and permissions within vSphere to enforce these controls.

Troubleshooting and Best Practices

Some VMs may fail during the migration, so you have to migrate them again and ensure that every one of your virtual machines was migrated successfully. The possible reason for failed migrations is when you try to migrate multiple VMs at the same time; hence, the best practice is to migrate your VMs one at a time.

Also, if you have ESX hosts that are not on vSphere 6.5, you will lose them once the migration is complete. VMFS 6 is only compatible with ESX hosts running vSphere 6.5 or newer versions. So, you should ensure to make all your ESX hosts run on vSphere 6.5 to avoid issues after the migration.

Furthermore, it is advisable to make a comprehensive backup before migrating data stores; things go so south in some cases, prompting you to recover from a backup. Interestingly, there are both free and paid backup tools that support VMware hypervisors or you can use a native backup solution and back up the physical hard drive that stores the VMFS partition containing your VMware VM VMDK files.

What to do in case of VMDK corrupt?

Addressing migration issues

Error Logs:

Review VMware Logs: Check VMware vCenter and ESXi host logs for any error messages or warnings that occurred during the migration process. Logs can provide detailed information on what went wrong and help identify specific issues.
Common Log Files:
- vpxd.log: Located on the vCenter Server, this log provides information about the vCenter Server activities.
- hostd.log: Found on the ESXi hosts, this log details the host's management activities.
- vmkernel.log: This log provides low-level details about the ESXi kernel operations and can help diagnose hardware and storage-related issues.

Connectivity Checks:

Network Connectivity: Ensure that the network connections between the ESXi hosts, vCenter Server, and storage devices are stable and functioning correctly. Network interruptions can cause migration failures.
Storage Connectivity: Verify that the storage devices are properly connected and accessible to the ESXi hosts. Check for any SAN or NAS connectivity issues that might affect the migration.

Resource Allocation:

Verify Resource Availability: Ensure that there are sufficient resources (CPU, memory, storage, and network bandwidth) available on the destination datastore and hosts to support the migrated VMs.
Adjust Resource Settings: If necessary, adjust resource allocation settings to prevent overcommitment and ensure optimal performance during and after migration.

Common Issues and Solutions:

Insufficient Space: If the destination datastore lacks sufficient space, either free up space or choose a different datastore with adequate capacity.
VM Snapshot Issues: Remove or consolidate any snapshots before migration, as multiple snapshots can cause migration failures.
Datastore Compatibility: Ensure that the source and destination datastores are compatible with the VM’s hardware version and requirements. Upgrading the hardware version of VMs might be necessary.

Retrying the Migration:

Step-by-Step Migration: Instead of migrating all VMs at once, try migrating a few VMs at a time to identify if specific VMs are causing issues.
Use VMware Tools: Utilize VMware’s built-in tools such as vMotion and Storage vMotion to handle migrations more effectively, as these tools are designed to minimize disruptions and handle various migration scenarios.

Consult VMware Documentation:

VMware Knowledge Base: Refer to the VMware Knowledge Base for solutions to specific error codes and issues. The Knowledge Base contains a wealth of information and troubleshooting steps for common migration problems.
VMware Community: Engage with the VMware community forums for advice and shared experiences from other users who may have encountered and resolved similar issues.

Engage VMware Support:

Technical Support: If the issue persists, contact VMware technical support for assistance. Provide them with detailed logs and descriptions of the issues you’re facing to get targeted help.

Note: how to repair Virtual Machine

How To Recover VM Data Lost During VMFS 6 Migration

If things go wrong when migrating your data store to a new one, and you didn’t make a prior backup, the best bet to turn around the situation is by using professional data recovery software.

There are cases where some people couldn’t find their important files after migrating to VMFS 6. Of course, if you made prior backups, you can just recover from there, but if not, the VMFS Recovery software by DiskInternals can come in handy to help you.

How to Use:

Download and install DiskInternals VMFS Recovery on your Windows OS computer; it runs on all Windows OS Editions and Windows Server 2003-2019
Launch the program and select the drive that stores your VMFS partition
Proceed to choose a data recovery mode; Fast Recovery or Full Recovery. However, it is advisable to choose Full Recovery.
Wait for DiskInternals VMFS Recovery to deeply scan your VMware VMFS datastores, disks, volumes, RAID (if used), and VMDK files. During the scanning process, this software will attempt to fix any corrupt files.
At the end of the scan, you will be presented with read-only access to the recovered files; you can preview these files before saving them back to your system. Also, to save the recovered files, you need the PRO version of DiskInternals VMFS Recovery.

Summary and benefits of migration

Migrating from VMFS 5 to VMFS 6 involves several key steps, including pre-migration preparation, executing the migration, validating functionality and performance, optimizing VMFS 6 features, and addressing any migration issues. This process ensures that your virtual environment is upgraded smoothly and efficiently, minimizing downtime and maintaining data integrity.

Benefits of Migration:

Enhanced Performance:
- Larger File Size Support: VMFS 6 supports larger single file sizes up to 64TB, beneficial for large virtual machines and applications requiring extensive storage.
- Improved I/O Performance: Advanced block sizes and optimized storage algorithms enhance I/O performance, particularly for demanding workloads.
Storage Efficiency:
- Automatic Space Reclamation: The UNMAP feature automatically reclaims unused storage space, maintaining efficient storage usage without manual intervention.
- Optimized Block Sizes: Support for 1MB and 512MB block sizes allows for better space utilization tailored to specific workload requirements.
Better Resiliency and Reliability:
- Modern Storage Integration: VMFS 6 is designed to work seamlessly with modern storage arrays, offering better integration and performance.
- Enhanced Locking Mechanism: The ATS (Atomic Test and Set) locking mechanism improves the reliability and performance of shared storage environments.
Advanced Security Features:
- Datastore-Level Encryption: VMFS 6 supports encryption at the datastore level, providing an additional layer of security for sensitive data.
- Improved Access Controls: Enhanced access control measures help prevent unauthorized access and ensure data security.
Future-Proofing:
- Compatibility with Latest VMware Features: Upgrading to VMFS 6 ensures compatibility with the latest VMware features and updates, keeping your infrastructure up-to-date.
- Support for New Technologies: VMFS 6 is designed to support new storage technologies and advancements, making it a future-proof choice for your virtual environment.
Ease of Management:
- Simplified Administration: Enhanced features and improved tools make managing VMFS 6 easier and more efficient.
- Consistent Performance: Regular maintenance tasks, such as automatic space reclamation and optimized storage policies, ensure consistent performance over time.

Tip: VMFS mount on Windows

By migrating to VMFS 6, you can take advantage of these benefits to improve the performance, efficiency, and security of your virtual environment. This upgrade not only enhances your current operations but also positions your infrastructure for future growth and technological advancements.

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