Category Archives: Virtualization

Get- and Set-VMLatencySensitivity PowerShell Function

The Get-VMLatencySensitivity, Get-VMLatencySensitivityBulk and Set-VMLatencySensitivity PowerShell functions configure can return and set the latency sensitivity level of a virtual machine. You can adjust the latency sensitivity of a virtual machine to optimize the scheduling delay for latency sensitive applications.

The function is part of my Virten.net.VimAutomation module, which is a set of PowerShell function built for managing, troubleshooting and automating VMware based platforms. The module can be easily obtained from the PowerShell Gallery and is available on GitHub.

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Critical Patch for All-Flash vSAN with Deduplication (6.0 and 6.5)

VMware has released a critical patch for vSAN 6.0 and 6.5. This patch contains a fix for a highly critical vSAN issue that might cause IO read errors and in some cases severe symptoms such as inaccessible VMs, host failures, or stuck resyncs. The issue manifests itself only under highly specific operations and IO patterns.

The bug only affects All-Flash vSAN configurations with deduplication enabled.

Symptoms for this issues are the following messages in the Events tab:

  • "vSAN detected an unrecoverable medium or checksum error for component uuid on disk group uuid."
  • "vSAN detected and fixed a medium or checksum error for component uuid on disk group uuid."

The following versions are affected according to KB2151042 and KB2151081.

Name Patch Date Build
ESXi 6.5 Update 1 ESXi650-update1 2017-07-27 5969303
ESXi 6.5 Update 1 (Security only) ESXi650-update1 2017-07-27 5969300
ESXi 6.5d (vSAN 6.6 Patch) ESXi650-201704001 2017-04-18 5310538
ESXi 6.5 Express Patch 1a ESXi650-201703002 2017-03-28 5224529
ESXi 6.5 Patch 1 ESXi650-201703001 2017-03-09 5146846
ESXi 6.5 Patch 1 (Security Only) ESXi650-201703001 2017-03-09 5146843
ESXi 6.5a ESXi650-201701001 2017-02-02 4887370
ESXi 6.5 GA 2016-11-15 4564106
ESXi 6.0 Update 3a (Patch 5) ESXi600-201706001 2017-06-06 5572656
ESXi 6.0 Update 3a (Patch 5) (Security Only) ESXi600-201706001 2017-06-06 5485776
ESXi 6.0 Express Patch 7a ESXi600-201703001 2017-03-28 5224934
ESXi 6.0 Update 3 ESXi600-update3 2017-02-24 5050593
ESXi 6.0 Update 3 (Security Only) ESXi600-update3 2017-02-24 5047589
ESXi 6.0 Patch 4 ESXi600-201611001 2016-11-22 4600944
ESXi 6.0 Patch 4 (Security Only) ESXi600-201611001 2016-11-22 4558694

VMware states that all vSAN customers using All-Flash with deduplication enabled must upgrade to this patch immediately:

Get-VMHostVersion and Get-VMHostLatestVersion PowerShell Function

The Get-VMHostVersion and Get-VMHostLatestVersion PowerShell functions are aimed at helping you to identify the version at which your ESXi is currently running, and whether updates are available. Both are using a JSON based ESXi Build database which is also the backend for the ESXi Build Number History provided by virten.net.

The function is part of my Virten.net.VimAutomation module, which is a set of PowerShell function built for managing, troubleshooting and automating VMware based platforms. The module can be easily obtained from the PowerShell Gallery and is available on GitHub.

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Convert-ScsiCode PowerShell Function

The Convert-ScsiCode PowerShell function decodes SCSI sense codes found in the vmkernel.log from ESXi hosts. It uses a JSON based SCSI Code database provided by virten.net. The function works just like my web-based SCSI Sense Code Decoder but allows you to integrate it in your automation scripts.

The function is part of my Virten.net.VimAutomation module, which is a set of PowerShell function built for managing, troubleshooting and automating VMware based platforms. The module can be easily obtained from the PowerShell Gallery and is available on GitHub.

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JSON Repository Format Update and now with SCSI Codes

Whenever I create databases with information like ESXi Versions, vCenter Versions or VMware's HCL I try make these available to be used for automation or in scripts. JSON is my data-type of choice but I figured that another structure might be easier to handle in some circumstances. This is why I've now created separate versions where it is now possible to access the information with keys.

Here is an example of the ESXi Releases JSON File, and the new V2:

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SCSI Sense Code Decoder OP Code Update

I've added a new feature to my online SCSI Sense Code Decoder. It is now possible to enter the Command that has been reported to be failed into the form. The command is displayed in the error message and can be important for troubleshooting:

The Command can be optionally entered in the form and will be translated:

Another small fix: Previously, Host Status and Sense Key fields were case sensitive and have to be entered in lower case. This requirement has been removed, you can now use lower or upper case letters.

The next feature I'm working on is to make the decoder to work with scripts to allow even better and faster troubleshooting. Any other feature requests are welcome.

VMware ESXi SCSI Sense Code Decoder

Using the first 3D Xpoint based Intel Optane SSD with ESXi

I could get my hands on Intel's first 3D XPoint based SSD to figure out how it performs.

3D XPoint is a new non-volatile memory technology that has been developed by Intel and Micron.

With 32GB, it doesn't make sense to buy them for anything else than their intended use case: Cache device to enhance SSD/HDD Performance. If you want to use Optane technology as VM Datastore, wait a couple of months when devices with a higher capacity are available.

 

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VCSA 6.5 Broken Filesystem - "Welcome to Emergency Mode"

Today I managed to crash the storage used in my home lab. After fixing the FreeNAS box, my vCenter Server Appliance (Version 6.5 Update 1) refused to boot and after opening the console, it welcomed me with the following error message:

Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to try again to boot into default mode.
Give root password for maintenance
(or press Control-D to continue):

Typically, this problem is caused by filesystem issues. This article explains how to fix the filesystem and get the appliance back up.

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What's inside VMware vSphere 6.5 Update 1

VMware has just released vSphere 6.5 Update 1 including the following producs:

If you want to get notified about new products, subscribe to my vTracker RSS Feed.

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vSAN 6.6 RVC Guide Part 6 - Troubleshooting

vSAN 6.6 RVC Guide

The "vSAN 6.6 RVC Guide" series explains how to manage your VMware Virtual SAN environment with the Ruby vSphere Console. RVC is an interactive command line tool to control and automate your platform. If you are new to RVC, make sure to read the Getting Started with Ruby vSphere Console Guide. All commands are from the latest vSAN 6.6 version.

The sixth part is about troubleshooting vSAN deployments.

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