Updating VMFS version from 5 to 6 while the VMs running on the datastore

Question: Can we update VMFS version from 5 to 6 while the VMs running on the datastore?

No, it’s not recommended to update the VMFS version while the VMs are running on the datastore. This can cause data corruption and lead to the loss of virtual machines. It’s best to schedule a maintenance window and shut down all virtual machines before upgrading the VMFS version.

Updating VMFS version from 5 to 6 while the VMs running on the datastore:

Best way to update VMFS version from 5 to 6 on the datastore –

The best way to update the VMFS version from 5 to 6 on the datastore is as follows:

1. Back up all virtual machines on the datastore. (or migrate the VMs to different datastore and make sure the datastore is empty)
2. Put all virtual machines in a powered-off state. (this step can be ignored if there are no VMs running on the datastore)
3. Unmount the datastore from all hosts that have access to it. (this step is only required when the VMs there on the datastore)
4. Upgrade the VMFS version using the vSphere Client or the CLI command “esxcli storage vmfs upgrade”.
5. Remount the datastore on all hosts that have access to it.
6. Power on virtual machines.

Note: Before starting the upgrade process, it’s important to check the compatibility of the storage devices and vSphere versions with VMFS 6.

New features of VMFS 6 version when compared with VMFS 5

VMFS 6 has several new features when compared to VMFS 5, including:

1. Larger file size limit: VMFS 6 supports larger virtual disks up to 62 TB compared to 2 TB in VMFS 5.
2. Scalability improvements: VMFS 6 supports up to 8,000 virtual machines per datastore and up to 64 nodes in a vSphere cluster.
3. Atomic Test and Set (ATS) awareness: VMFS 6 supports the ATS feature, which reduces SCSI reservation conflicts and improves performance in multi-writer environments.
4. Improved alignment of virtual disk blocks: VMFS 6 aligns virtual disk blocks to a 1 MB boundary, which reduces overhead and improves performance.
5. New disk format: VMFS 6 uses a new disk format that supports larger block sizes and increases the number of available metadata operations.
6. Improved UNMAP: VMFS 6 has improved UNMAP support for thin-provisioned virtual disks, which reduces storage waste and reclaims unused space more efficiently.
7. Larger metadata operations: VMFS 6 allows for larger metadata operations, which improve the performance of operations such as snapshots and cloning.