This page contains my notes for the VMware VCAP4-DCA exam as based on the VCAP4-DCA Blueprint (version 1.9 as of the writing of these notes).

Section 1. Implement and Manage Storage

Objective 1.1 Implement and Manage Complex Storage Solutions

• Determine use cases for and configure VMware DirectPath I/O
• Use Cases: Virtual machines that need to directly access an I/O device, bypassing the virtualization layer.  This can improve performance for ESX systems that utilize high-speed I/O devices, such as 10 Gigabit Ethernet. (Source: Configuration Examples and Troubleshooting for VMDirectPath VMware ESX 4.0 Page 1)
• Configuring: Select a host from the inventory panel of the vSphere client.  On the Configuration tab, click Advanced Settings.  Click Edit.  Select the devices to be used for passthrough and click OK. (Source: ESXi Configuration Guide 4.0 Page 57)
• Determine requirements for and configure NPIV
• Requirements: The following requirements and limitations exist:
• NPIV can only be used for virtual machines with RDM disks.  Virtual machines with regular virtual disks use the WWNs of the host’s physical HBAs.
• For this implementation of NPIV, the physical HBAs on an ESX/ESXi host, using their own WWNs, must have access to all LUNs that are to be accessed by virtual machines running on that host.
• The ESX/ESXi host’s physical HBAs must support NPIV.  Currently, the following vendors and types of HBA provide this support:
• QLogic – any 4GB HBA
• Emulex – 4GB HBAs that have NPIV-compatible firmware
• Only four WWN pairs are generated per virtual machine
• When a virtual machine or template with a WWN assigned to it is cloned, the clones do not retain the WWN
• The switches used must be NPIV-aware
• When configuring a NPIV LUN for access at the storage level, make sure that the NPIV LUN number and NPIV target ID match the physical LUN and Target ID
• Always use the vSphere Client to manipulate virtual machines with WWNs

(Source: Fibre Channel SAN Configuration Guide Page 58)

Configuring: Either assign a WWN to a new virtual machine with a RDM disk when you create the virtual machine, or to an existing virtual machine that you can temporarily power off.  From the vSphere client right-click on a virtual machine that is powered off and select Edit Settings.  Select the Options tab.  Select Fibre Channel NPIV.  In the dialog box you can select one of the following options:

• Leave Unchanged: The existing WWN assignments are retained.  The read-only WWN Assignments section of this dialog box displays the node and port values of any existing WWN assignments.
• Generate new WWNs: New WWNs are generated and assigned to the virtual machine, overwriting any existing WWNs (those of the HBA itself are not unaffected).
• Remove WWN assignment: The WWNs assigned to the virtual machine are removed and it uses the HBA WWNs to access the storage LUN.  This option is not available if you are creating a new virtual machine.

(Source: Fibre Channel SAN Configuration Guide Page 59)

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