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Quick Tip - Correlating VMFS Datastore to Storage Device Using ESXCLI

07.15.2013 by William Lam // 1 Comment

There was a question on Twitter this morning from AJ Kuftic on whether it is possible to display the mapping of a VMFS Datastore to its respective storage device using ESXCLI. Josh Coen beat me to the answer this morning, but yes it is possible using ESXCLI. I thought I still share this quick tip as it may not be obvious, especially when you need this information while performing a storage maintenance or troubleshooting with your storage administrator.

For those of you who are familiar with the legacy esxcfg-* commands, this information can be retrieved using the following command:

esxcfg-scsidevs -m

You can also retrieve this same information by using the following ESXCLI command (can be executed remotely as well):

esxcli storage vmfs extent list

As you can see from both screenshots, we can easily identify the name of the VMFS datastore and the specific storage device it is mapped along with other pieces of information. I prefer the ESXCLI method as it is nicely formatted along with the title header for each property.

Categories // Uncategorized Tags // datastore, esxcli, ESXi, vmfs, vSphere

Emulating an SSD Virtual Disk in a VMware Environment

07.03.2013 by William Lam // 32 Comments

I continue to be amazed everyday at all the awesome features and challenges being tackled by our VMware Engineering organization and yesterday was another example of that. There was a question that was posed internally about emulating an SSD device for a Nested ESXi environment running in VMware Fusion. I figure this would be an easy answer and pointed the user to a blog article I had written a few years ago on how to fake an SSD device in ESXi using SATP claim rules via ESXCLI. It turns out, one of the engineers knew of a better way of emulating an SSD Virtual Disk that can be consumed beyond just Nested ESXi VMs but also for any other guestOSes that supports SSD devices.

So why would you want to emulate an SSD device? Well for a vSphere environment, you may want to try out the new Swap to Host Cache feature from a functional perspective to see how it would work. You might be developing a script to enable this feature and having a "fake" SSD device would allow you to create such a script and test it. For other guestOSes, maybe you want to see how the system would react to an SSD device, perhaps drivers or configurations maybe needed and you would like to run through those processes before installing a real SSD device.

So the solution is actually quite simple and it is just an advanced setting in the Virtual Machine's configuration file (VMX) which can also be appended to using either the vSphere Web Client, vSphere C# Client or the vSphere API. This setting is only supported on Virtual Machines that is running virtual hardware 8 or greater. To configure a specific virtual disk to appear as an SSD, you just need to add the following:

scsiX:Y.virtualSSD = 1

where X is the controller ID and the Y is the disk ID of the Virtual Disk.

This configuration presents to the guestOS the mediumRotationRate field of the SCSI inquiry pages 0xB1 and sets the value to 1 and the guests will then report it as a solid-state device. As you can see, this can benefit more than just running Nested ESXi, you can also do various testing on other guestOSes that you require a "fake" SSD device.

Note: Though you can emulate an SSD device, it is no substitute for an actual SSD device and any development or performance tests done in a simulated environment should also be vetted n a real SSD device, especially when it comes to performance.

It is also important to note that reporting of an SSD device will highly depend on the guestOS, here is a high level table on how some of the common guestOSes recognize SSD devices.

GuestOS SSD Reporting
Windows 8 IDE, SCSI and SATA disks can be recognized as SSDs
Windows 7 IDE and SATA disks can be recognized SSD, but SCSI as mechanical
Linux (Ubuntu & RHEL) IDE, SCSI and SATA disks can be recognized as SSDs
Mac OS X SATA can be recognized as SSDs, but IDE and SCSI as mechnical

Here is a screenshot of a Nested ESXi host with an emulated SSD device:

Here is a screenshot of the new Windows 8.1 Preview with an emulated SSD device:

Note: Though I demonstrated this using vSphere, this also works for VMware Fusion (tested this personally), Workstation and Player. The only requirement is that you are running virtual hardware 8 or greater and that your guestOS supports reporting SSD device.

From a Nested ESXi perspective, I will definitely be using this method instead of using ESXCLI to go through the SATP claim rules, this is much easier to remember. I would also like to thank Regis Duchesne for sharing this tip and Srinivas Singavarapu and the virtual devices team for developing this awesome feature. You guys ROCK!

Categories // Uncategorized Tags // ESXi, solid state drive, ssd, virtual disk, vmdk, vSphere

Quick Tip - Listing Image Profiles From an ESXi Patch Using ESXCLI

06.21.2013 by William Lam // 6 Comments

I was cleaning out a few of my to-do items (list just keeps getting longer everyday) this morning and there was a question that I received a few weeks back asking how to retrieve the list of Image Profiles for a given ESXi patch. This is actually quite easy and you will want to use ESXCLI.

Note: The examples shown below is using ESXCLI on the ESXi Shell, but these commands can be execute remotely as well using ESXCLI or through PowerCLI with Get-EsxCli cmdlet.

To list the available Image Profiles for an ESXi patch, run the following command (ensure you substitute the full path to your ESXi patch):

esxcli software sources profile list -d /vmfs/volumes/datastore1/ESXi510-201212001.zip

To get more details on a particular Image Profile, run the following command and specify the -p for the specific Image Profile:

esxcli software sources profile get -d /vmfs/volumes/datastore1/ESXi510-201212001.zip -p ESXi-5.1.0-20121204001-no-tools

To install/update a specific Image Profile, run the following command with the Image Profile name:

esxcli software profile update -d /vmfs/volumes/datastore1/ESXi510-201212001.zip -p ESXi-5.1.0-20121204001-no-tools

If you just want to install the ESXi patch, run the following command which will install the esx-base Image Profile by default which will include everything:

esxcli software vib update -d /vmfs/volumes/datastore1/ESXi510-201212001.zip

To check for the Image Profile you have installed on your ESXi host, run the following command:

esxcli software profile get

Here are some additional resources for ESXi patch management that may also be useful:

  • Quickest Way to Patch an ESX/ESXi Using the Command-line
  • Update a Host with Image Profiles
  • Understanding ESXi Patches - Size & Patch Bundles
  • A Pretty Cool Method of Upgrading to ESXi 5.1

Categories // Uncategorized Tags // esxcli, ESXi, image profile, vib

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William is Distinguished Platform Engineering Architect in the VMware Cloud Foundation (VCF) Division at Broadcom. His primary focus is helping customers and partners build, run and operate a modern Private Cloud using the VMware Cloud Foundation (VCF) platform.

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