VMware FAQ

On this page

What versions of VMware ESXi are supported?

VMware ESXi 6.0 and later.

Will VMware ESXi free version work?

We cannot back up from the free version of VMware ESXi. Free version does not allow access to the VMware storage APIs we need to back up data.

What license do I need?

Under licensed features, need the storage APIs listed.

What is ignore unallocated sectors?

Use CBT to find out what parts of VMDKs have never been used, and skip those sectors to speed backup.

What is quiesce data?

When taking the snapshot of a VM, we can ask VMware to quiesce data. VMware will signal the VMware tools running in the guest operating system, which will signal the operating system (via VSS in Windows). The programs on the guest operating (for example, Microsoft SQL server) and the file system of the operating system should put their data files in a consistent state like they would during a shutdown. Once that is done, the snapshot is taken, and the guest operating system resumes normal operation. This is to allow a VM backup to be restored and used immediately without needing to wait for file system or database repairs.

What is Changed Block Tracking?

Changed Block Tracking (CBT) is a feature of VMware that timestamps changes to blocks of disk so later backups can skip copying blocks of disk that have not changed since the last backup.

What do I need to use Changed Block Tracking for?

To enable CBT the following VMware conditions must be met:

  • The host must be ESXi 6.0 or later.

  • The virtual machine owning the disks to be tracked must be hardware version 11 or later.

  • I/O operations must go through the ESXi storage stack.

    So NFS is supported, as is RDM in virtual compatibility mode, but not RDM in physical compatibility mode. Of course VMFS is supported, if backed by SAN, iSCSI, or local disk.

  • CBT must be enabled for the virtual machine (see below).

  • Obviously, virtual machine storage must not be (persistent or non-persistent) independent disk mode, meaning unaffected by snapshots.

  • The virtual disk must be located on a VMFS volume, backed by SAN, iSCSI, or local disk. RDM is not VMFS.

  • The virtual machine must have zero (0) snapshots when CBT is enabled, for a clean start.

Can I back up virtual machine without taking its snapshot?

Not through the VMware integration. If VMware cannot make a complete snapshot of a VM, we recommend backing it up by installing the backup agent on its guest operating system.

Can I back up VMDK files in persistent mode?

Not through VMware integration. Persistent mode means that a VMDK cannot have a snapshot taken (though VMware will still snapshot other parts of a VM). Without a snapshot we cannot know that the guest operating will not be changing the contents of the virtual disk while we are backing it up. There is one exception, if the VM is powered down then we will be able to get exclusive access to the VMDK, but the VM cannot be powered on until the backup is complete. We recommend installing the backup agent in the guest operating system.

Can I back up virtual machine with NVMe controller?

No, Infrascale Backup & Disaster Recovery does not support backup of VMware VMs with NVMe controllers.

How to restart host services?

Follow the instructions provided by VMware found here.

Can I back up RDM disks?

Only if it is used in the virtual mode (allowing for snapshots).

What is maximum VMDK size that can be backed up?

If VMware is unable to create a snapshot, it is too big.

Does CFA create user for itself in vCenter?

No, it continues to use the username it was given when first setup. If the password on that account is changed, or the account is disabled or removed, VM backups will fail.