esxi

How do you “log a reason” using PowerCLI when rebooting or shutting down ESXi host?

06/04/2018 by William Lam 1 Comment

I am sure many of you have seen this UI prompt asking you to specify a reason before issuing a reboot or shutdown of an ESXi host and I assume most of you spend a few seconds to type in a useful message and not just random characters, right? 😉

Have you ever tried performing the same reboot or shutdown operation using the vSphere API or PowerCLI (which leverages the API)? Have noticed, there is not a way to specify a message like you can in the UI?

Here is a table of the PowerCLI cmdlets and the respective vSphere API that is used to perform these two operations:

Operation	Cmdlet	vSphere API
Reboot	Restart-VMHost	RebootHost_Task
Shutdown	Stop-VMHost	ShutdownHost_Task

When looking at either the PowerCLI and/or vSphere API documentation, we can confirm that there are no fields to specify a message which can lead to an assumption that this is simply not possible or that the functionality might be provided by a private API. Fortunately, this is not the case and the functionality is in fact in the public vSphere API and has been for quite some time.

When you specify a message prior to rebooting or shutting down, this message is actually persisted and implemented as an Event within vCenter Server as shown in the screenshot below.

Instead of being able to specify a message that is only applicable to an ESXi host, I believe the original vSphere API designers thought that this functionality could also be useful and applied more broadly across any number of the vSphere Inventory objects, not just ESXi hosts. As such, this functionality which the vSphere UI uses is provided by the LogUserEvent() method which is part of the EventManager API. Customers or solutions can leverage this mechanism to log custom user defined events which is then persisted with the lifecycle fo the vSphere Inventory Object or as far back as your retention period for vCenter Server Events.

Going back to our original question, if you want to specify a message prior to rebooting or shutting down an ESXi host, the following snippet below demonstrates the use of the vSphere API via PowerCLI:

$eventManager = Get-View eventManager
$vmhost = Get-VMHost -Name 192.168.30.11
$message = "This message will be logged"

$eventManager.LogUserEvent($vmhost.ExtensionData.MoRef,$message)

$eventManager = Get-View eventManager

$vmhost = Get-VMHost -Name 192.168.30.11

$message = "This message will be logged"

$eventManager.LogUserEvent($vmhost.ExtensionData.MoRef,$message)

Quick Tip – What hashing algorithm is supported for ESXi Kickstart password?

05/21/2018 by William Lam Leave a Comment

I had a question the other day asking whether the encrypted password which can be specified within an ESXi Kickstart file (denoted by the --isencrypted flag) can use a different hashing algorithm other than MD5? The answer is absolutely yes. In fact, MD5 as a default hashing algorithm has NOT been used for a number of releases, probably dating back to classic ESX (you know, the version that had the Service Console).

For all recent releases of ESXi including 5.5 to 6.7, the default hashing algorithm has been SHA512 for quite some time now. Below are two ways in which you can check which default hashing algorithm is currently being used:

Option 1 - SSH to ESXi host and take a look at /etc/pam.d/passwd

Option 2 - SSH to ESXi host and take a look at /etc/shadow and look at the field prior to the salt.

As a reference:

$1$ - MD5
$5$ - SHA256
$6$ - SHA512

New VMware Configuration Maximum Tool

04/13/2018 by William Lam 1 Comment

VMware has just released a new web-based tool that will enable customers to easily view and compare product configuration maximums across different VMware product versions. You can access the easy to remember URL by going to: https://configmax.vmware.com

In this first release of this tool, customers will have the ability to look up configuration maximums for vSphere (includes VSAN) which will initially support vSphere 6.0, vSphere 6.5, vSphere 6.5 Update 1 & the recently released vSphere 6.7 as well as comparing across versions. To view the existing vSphere configuration maximum, simply click on the "Get Started" button.

As you can see from the screenshot below, you now have a single place where you can view the vSphere configuration maximums across different versions. Once you have selected the target version, you can either view all maximums or you can selectively choose the sections you are interested in.

The other really neat feature is the ability to compare the configuration maximums across different vSphere versions. This is really useful for customers to be able to quickly tell what improvements and enhancements have been made, especially as customers plan for vSphere upgrades. To begin, simply click on the "Compare Limits" button at the top. Next, select the target vSphere version and then you can add one or more versions to compare against.

Once you click on the Compare button, a new window will popup providing you the comparison between the target and selected vSphere versions. You can quickly see how the maximums have changed across these vSphere versions. You can even export the results to Excel by click on export option on the upper right hand corner and you be prompted to save a CSV file.

I can tell you, this definitely beats having to manually Google for the correct vSphere configuration maximum document since I can never remember the long URL to the static PDF documents! I am excited to see the improved user experience when consuming our product maximums and I know the team will be working on adding more products and features in the future. Definitely keep an eye on this site and also be sure to update your bookmarks. If you have any feedback or things you would like to see, feel free to leave a comment and I will make sure it reaches the Product and Development teams.

ESXi host with network redundancy using NSX-T and only 2 pNICs?

03/27/2018 by William Lam 4 Comments

In todays data centers, it is not uncommon to find servers with only 2 x 10GbE network interfaces, this is especially true with the rise of Hyper-Converged Infrastructure over the last several years. For customers looking to deploy NSX-T with ESXi, there is an important physical network constraint to be aware of which is quickly mentioned in the NSX-T documentation here.

For example, your hypervisor host has two physical links that are up: vmnic0 and vmnic1. Suppose vmnic0 is used for management and storage networks, while vmnic1 is unused. This would mean that vmnic1 can be used as an NSX-T uplink, but vmnic0 cannot. To do link teaming, you must have two unused physical links available, such as vmnic1 and vmnic2.

As shown in the diagram below, an ESXi host with only two physical NICs can not provide complete network redundancy as each pNIC can only be associated with a single switch (VSS/VDS or the new N-VDS) as pNICs can not be shared across switches.

For customers, this means that you need to allocate a minimum of 4 pNICs to provide redundancy for both overlay traffic and non-overlay VMkernel traffic such as Management, vMotion, VSAN, etc. This is much easier said than done as not all hardware platforms can easily be expanded and even if they can, there still is a huge cost in expanding the physical network footprint (switch port, cabling, etc).

UPDATE (06/12/18) - As of NSX-T 2.2, which was recently released, there is now a UI in NSX-T Manager for managing the migration of VMkernel interfaces to the N-VDS. For automation purposes, you may still find this article useful but now you have option of using the UI.

Thunderbolt to 10GbE Network Adapters for ESXi

03/15/2018 by William Lam 4 Comments

I was recently made aware of this article in which the author, Karim Elatov, had successfully demonstrated the use of a Sonnett Thunderbolt 2 to 10 Gigabit Ethernet Adapter with ESXi running on an Apple Mac Mini. As far as I am aware of, this may be the first public confirmation that such a device would work with ESXi, not to mention having it functional on the Mac Mini. I know in past years, there have been unconfirmed reports on various forums mentioning a Thunderbolt to 10GbE solution that works with ESXi but it was unclear on whether custom drivers were needed or if it would even work with newer versions of ESXi.

This topic has been popular amongst our customers who virtualize Apple MacOS on vSphere. In fact, several years back I had written an article on Thunderbolt Storage for ESXi, which includes a number of solutions that our customers have implemented to provide remote storage for their vSphere infrastructure running on either an Apple XServe, Mac Pro or Mac Mini. Questions around a functional Thunderbolt to 10GbE has definitely been asked about, but I had never heard from any customer who have had a successful story to share, at least until now.

From Karim's post, it looks like he was able to get this working using ESXi 6.0 but it was unclear if there was anything he needed to do to get the device recognized. I reached out to Karim and he was able to confirm that the Thunderbolt device was recognized by ESXi without any additional driver installation. In fact, if you look at this console output on his blog, you will see that it simply uses the inbox Intel ixgbe driver. I had also asked if Karim tried this with the latest version of ESXi, which is currently at 6.5 Update 1. Karim was kind enough to perform one additional test for me which was to confirm the device would still work with the latest ESXi release, which you can see for yourself in the screenshot below.

Identifying ESXi boot method & boot device

01/09/2018 by William Lam 6 Comments

There was an interesting discussion on our internal Socialcast platform last week on figuring out how an ESXi host is booted up whether it is from local device like a disk or USB device, Auto Deploy or even boot from SAN along with its respective boot device? Although I had answered the question, I was not confident that we actually had a reliable and programmatic method for identifying all the different ESXi boot methods, which of course piqued my interest.

With a bit of trial and error in the lab, I believe I have found a method in which we can identify the ESXi boot type (Local, Stateless, Stateless Caching, Stateful or Boot from SAN) along with some additional details pertaining to the boot device. To demonstrate this, I have created the following PowerCLI script ESXiBootDevice.ps1 which contains a function called Get-ESXiBootDevice.

The function can be called without any parameters, in which it will query all ESXi hosts for a given vCenter Server and/or standalone ESXi host. You can also specify a specific ESXi host by simply passing in the -VMHostname option.

Here is an example output for one of my lab environments which shows several ESXi hosts and their different boot methods from local disk to Auto Deploy which can include stateless, stateless caching and stateful deployments. Depending on the BootType, the boot device shown in the Device column will either be the MAC Address of the NIC used to network boot the ESXi host or the identifier of a disk device. I have also included some additional details such as vendor/model along with the media type (SAS, SSD or USB) which is available as part of ESXCLI.

This script also supports ESXi environments that boot from SAN (FC, FCoE or iSCSI) and you can easily identify that with the word "remote" for the BootType. I would like to give a huge thanks to David Stamen who helped me out with the boot from SAN testing.