DO NOT clone ESXi boot devices!

Some of admins are keen to clone ESXi boot device in order to speed up the deployment. Please remember that this workflow is not at all supported by VMware.

NOTE: After upgrading to ESXi 7.0U2, corruption can occur on VMFS datastores if the ESXi hosts sharing those LUNs had their boot devices cloned (84349)

This may happen as ESXi’s operating system expects that each server will have a unique System Universally Unique Identifier (UUID). However if ESXi boot devices is clonede also the System UUID is replicated, which can lead to VMFS corruption if multiple hosts with the same System UUID share the same VMFS volumes, as there are dependencies in the storage stack that uses the System UUID for operations like VMFS journaling and VMFS Heartbeat operations.

There are additional dependencies on unique System UUIDs in ESXi 7.0 (Encrypted keys for TPM, etc) as we always expect the System UUID to be unique and not copied.

The only supported solution at this time is to rebuild the ESXi hosts, which will generate a new System UUID. Any datastores that become corrupt as a result of duplicate System UUIDs will need to be reformatted after evacuating the present VMs.

When an ESXi boot device is cloned, the System Universal Unique Identifier (UUID) is also cloned. This identifier is used for VMFS Heartbeat and Journal operations so if multiple hosts have the same UUID, this case lead to a split-brain situation as the ESXi hosts will attempt to access each other’s metadata regions on VMFS. The most common form of cloned ESXi boot devices is cloned boot LUNs for rapid deployments.

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