6.0

Prerequisites
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To edit the virtual machine’s WWNs, power off the virtual machine.
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Verify that the virtual machine has a datastore containing a LUN that is available to the host.
Procedure
1 In the vSphere Client inventory, right-click the virtual machine and select Edit Settings.
2 Click the Options tab and under Advanced select Fibre Channel NPIV.
3 (Optional) Select the Temporarily Disable NPIV for this virtual machine check box.
4 Assigned WWNs appear in the WWN Assignments panel.
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To leave WWNs unchanged, select Leave unchanged.
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To have the ESXi host generate new WWNs, select Generate New WWNs.
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To remove the current WWN assignments, select Remove WWN assignment.
5 Click OK to save your changes.
6 Provide the WWN assignments to your SAN administrator.
The administrator needs the assignments to configure virtual machine access to the LUN.
Virtual Disk Configuration
You can add large-capacity virtual disks to virtual machines and add more space to existing disks, even
when the virtual machine is running. You can set most of the virtual disk parameters during virtual
machine creation or after you install the guest operating system.
You can store virtual machine data in a new virtual disk, an existing virtual disk, or a mapped SAN LUN. A
virtual disk, which appears as a single hard disk to the guest operating system, is composed of one or more
files on the host file system. You can copy or move virtual disks on the same hosts or between hosts.
For virtual machines running on an ESXi host, you can store the virtual machine data directly on a SAN
LUN instead of storing it in a virtual disk file. This ability is useful if you are running applications in your
virtual machines that must detect the physical characteristics of the storage device. Additionally, mapping a
SAN LUN allows you to use existing SAN commands to manage storage for the disk.
To accelerate virtual machine performance, you can configure virtual machines to use vSphere Flash Read
Cache™. For details about Flash Read Cache behavior, see the vSphere Storage documentation.
When you map a LUN to a VMFS volume, vCenter Server or the ESXi host creates a raw device mapping
(RDM) file that points to the raw LUN. Encapsulating disk information in a file allows vCenter Server or the
ESXi host to lock the LUN so that only one virtual machine can write to it. This file has a .vmdk extension,
but the file contains only disk information that describes the mapping to the LUN on the ESXi system. The
actual data is stored on the LUN. You cannot deploy a virtual machine from a template and store its data on
a LUN. You can store only its data in a virtual disk file.
The amount of free space in the datastore is always changing. Ensure that you leave sufficient space for
virtual machine creation and other virtual machine operations, such as growth of sparse files, snapshots,
and so on. To review space utilization for the datastore by file type, see the vSphere Monitoring and
Performance documentation.
Thin provisioning lets you create sparse files with blocks that are allocated upon first access, which allows
the datastore to be over-provisioned. The sparse files can continue growing and fill the datastore. If the
datastore runs out of disk space while the virtual machine is running, it can cause the virtual machine to
stop functioning.
vSphere Administration with the vSphere Client
160 VMware, Inc.