Backing up independent disks and RDMs

VMware vSphere does not provide snapshots of independent disks or of Raw Device Mapping (RDM) disks in physical compatibility mode. Therefore, Agent for VMware cannot back up such disks when the virtual machine is online or suspended.

When a virtual machine is online, the agent skips these disks and adds warnings to the log. You can avoid the warnings by excluding independent disks and RDMs in physical compatibility mode from the backup plan.

A suspended machine with independent disks or RDMs cannot be backed up at all. The backup will fail.

When a virtual machine is offline (powered off), Agent for VMware can access the independent disks and RDMs in physical compatibility mode via ESX(i). Then, the agent can copy the information from them in a consistent state. As a result, the agent is able to back up all of the disks regardless of their mode.

The following table shows the role which the state of a virtual machine plays on whether Agent for VMware can back up a disk. The table applies to all versions of ESX(i) supported by the agent.


VM disk modes	ESX(i) machine state
VM disk modes	Online	Suspended	Offline
Basic virtual	+	+	+
Independent persistent	–	–	+
Independent nonpersistent	–	–	+
RDM in physical compatibility mode	–	–	+
RDM in virtual compatibility mode (basic virtual)	+	+	+
RDM in virtual compatibility mode (independent persistent)	–	–	+
RDM in virtual compatibility mode (independent nonpersistent)	–	–	+

If you want to back up independent disks and RDMs in physical compatibility mode, do one of the following, depending on your business process:

To back up independent disks and RDMs while the machine in the online state, install Agent for Windows or Agent for Linux in the guest operating system.
An Acronis Backup Advanced license assigned to the host enables you to install agents in an unlimited number of guest systems.

For more information about how to install the agent, see the installation documentation.

After you install the agent and add the machine to the management server, the machine appears under Machines with agents in the All machines with agents group. When creating a backup plan, select the machine here rather than under Virtual machines. Or, you can connect the console to the machine directly as to a physical machine.

You might want to use a different backup strategy for independent disks or RDMs in physical compatibility mode. For example, if these disks contain frequently changing databases, you can back them up more often than the operating system, or use different settings for them. In this case, create a separate backup plan for these disks.
To back up independent disks and RDMs on a machine that regularly goes offline, use Agent for VMware and schedule the backup for these offline hours.
Please make sure that the backup is completed within the offline hours. VMware vSphere will not be able to power on the machine while the backup is in progress. This is because the independent disks and RDMs in physical compatibility mode are locked by Agent for VMware during backup.