6.7

Add an RDM Disk to a Virtual Machine
You can use a raw device mapping (RDM) to store virtual machine data directly on a SAN LUN, instead of
storing it in a virtual disk file. You can add an RDM disk to an existing virtual machine, or you can add the
disk when you customize the virtual machine hardware during the virtual machine creation process.
When you give a virtual machine direct access to an RDM disk, you create a mapping file that resides on
a VMFS datastore and points to the LUN. Although the mapping file has the same .vmdk extension as a
regular virtual disk file, the mapping file contains only mapping information. The virtual disk data is stored
directly on the LUN.
During virtual machine creation, a hard disk and a SCSI or SATA controller are added to the virtual
machine by default, based on the guest operating system that you select. If this disk does not meet your
needs, you can remove it and add an RDM disk at the end of the creation process.
Prerequisites
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Ensure that you are familiar with SCSI controller and virtual device node behavior for different virtual
hard disk configurations. See Add a Hard Disk to a Virtual Machine.
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Before you add disks greater than 2TB to a virtual machine, see Large Capacity Virtual Disk
Conditions and Limitations.
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Required privilege: Virtual machine.Configuration.Raw device
Procedure
1 Right-click a virtual machine in the inventory and select Edit Settings.
2 On the Virtual Hardware tab, add a new RDM disk. select RDM Disk from the New device drop-
down menu and click Add.
Client Steps
vSphere Client Click the Add New Device button and select RDM Disk from the drop-down
menu.
vSphere Web Client a Select RDM Disk from the New device drop-down menu at the bottom of the
wizard.
b Click Add.
The Select Target LUN dialog box opens.
3 In the Select Target LUN dialog box, select the target LUN for the raw device mapping and click OK.
The disk appears in the virtual device list.
4 Select the location for the mapping file.
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To store the mapping file with the virtual machine configuration file, select Store with the virtual
machine.
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To select a location for the mapping file, select Browse and select the datastore location for the
disk.
vSphere Virtual Machine Administration
VMware, Inc. 111