Monthly Archives: October 2014

VCAP5-DCA – – Implement Complex Storage Solutions – Skills and Abilities – Identify and tag SSD devices

Identify and tag SSD devices:

This is well covered in the vSphere Storage guide.

Identify an SSD: 

Before you identify an SSD device, ensure that the device is tagged as SSD.
From the CLI, the procedure is to list the devices.
esxcli storage core device list
and then review the command output includes the following information about the listed device.
Is SSD: true
Verify whether the value of the flag Is SSD is true.

From the vSphere client Host summary includes a column ‘Drive Type’ with possible values Non-SSD, SSD or Unknown (NFS datastores).

If you have an SSD that is not detected as one or you need to emulate an SSD in a lab environment you can manually tag the datastore as SSD. The process is documented In the vsphere documentation

  1. Identify the device to be tagged and its SATP.

    esxcli storage nmp device list 

  2. Add a Claim Rule to mark the device as SSD

 esxcli storage nmp satp rule add -s SATP –device device_name –option=enable_ssd

  1. Unclaim the device

esxcli storage core claiming unclaim –type device –device device_name

  1. Enable to new claim rule and load it into memory

        esxcli storage core claimrule load

        esxcli storage core claimrule run

5. Make sure that it worked
        esxcli storage core device list -d device_name

The command output indicates if a listed device is tagged as SSD.

Is SSD: true 


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VCAP5-DCA – – Implement Complex Storage Solutions – Skills and Abilities – Determine use cases for and configure VMware DirectPath I/O

DirectPath I/O is available from vSphere 4.0 forward. It uses Intel VT-d and AMD-Vi to allow guests to directly access hardware devices. When using DirectPath a VM can’t use vMotion, snapshots or any feature which leverage them.  The directly allocated device isn’t available to other VMs. The only change with vSphere5 is that you can vMotion a VM provided it is in a supported hardware configuration that allows that direct path to the host hardware to persist.

The benefit of DirectPath is very specific. You can offload CPU cycles that the VMM would need to perform to schedule those resources and expose hardware component features that are not yet available through virtualized drivers or that ESXi cannot recognize. There is a performance benefit available in some cases.

The tradeoff is to nearly nullify the benefit of agility inherent in virtualization, effectively tying a guest to a host.

There is a KB describing the configuration process.

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My notes for the VCAP5-DCA exam

I am starting to put together my notes for the VCAP5-DCA exam.

Some of this will be restated information from other sources, and I’ll try to site references where possible, but because I’m really just collecting my own thoughts here, your mileage may vary.

My Plan:

The plan is to review all of the information in the Blueprint

I will post a description of each topic and notes about how to affect the topic. My goal is to have identified places where I rely heavily on documentation and would be  hindered in the exam.

After I note each category I will take some highlights and recreate them in a video. This is new territory for me so I may not be quick to get these posted.

Let’s see how long this takes me to really get done.

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