Author Archives: fgrehl - Page 2

vSphere 6.5 Component Password Recovery (vCenter, SSO and ESXi)

Everyone knows the situation where you can't log into a system because you have forgotten the password. The following article explains how to reset the password and regain access to VMware vSphere 6.5 core components including vCenter, SSO and ESXi Hosts.

  • Reset vCenter Server Appliance 6.5 root password
  • Reset SSO Administrator Password (vCenter Server Appliance 6.5)
  • Reset ESXi root password with Host Profiles
  • Gain Administrative ESXi access with an Active Directory
  • Reset ESXi root password (Linux Live CD)

Read more »

Home Lab Power Management Tipps

Home labs are great to study, extend your knowledge and try out new features. Of course, the hardware is also useful to be used for other purposes like file servers, home automation, media streaming servers and so on.

There are some features to be considered for any type of deployment at home to have a better control and maybe to save some money.

Read more »

SSD Total Bytes Written Calculator

Solid-State-Drives are getting more and more common. A problem that comes with SSDs is their limited cell lifetime. Depending on their manufacturing technique, each cell can be overwritten from 1.000 times in consumer TLC SSDs to up to 100.000 times in enterprise SLC based SSDs.

The value to keep an eye on is the guaranteed TBW (Total Bytes Written or Terabytes Written) which is typically provided by the vendor in their specifications. This value describes how many Terabytes can be written to the device until the warranty expires. The TBW value can be readout with S.M.A.R.T. in the Total_LBAs_Written field. The value is in LBAs which has to be multiplied with the sector size: Read more »

The Physical block size reported by the device is not supported

Since my ESXi hosts are upgraded to VMware vSphere ESXi 6.5, the vmkernel.log is constantly spammed with warnings reporting that the physical block size from my LUNs, provided by a FreeNAS storage, have an unsupported block size.

WARNING: ScsiPath: 4394: The Physical block size "131072" reported by the path vmhba64:C0:T4:L0 is not supported. The only supported physical blocksizes are 512 and 4096
WARNING: ScsiDeviceIO: 6462: The Physical block size "131072" reported by the device naa.6589cfc0000000572b71f35019e9c31f is not supported. The only supported physical blocksizes are 512 and 4096

I'm using FreeNAS-9.10.2 with iSCSI LUNs backed by a ZFS volume. The physical blocksize is reported as the ZFS recordsize which is 128K by default. Read more »

USB Devices as VMFS Datastore in vSphere ESXi 6.5

intel-nuc-with-usb3-connected-ssdIn ESXi 6.5, there are some changes concerning devices connected with USB. The legacy drivers, including xhci, ehci-hcd, usb-uhci, and usb-storage have been replaced with a single USB driver named vmkusb. The new driver has some implications if you are trying to use USB devices like USB sticks or external hard disks as VMFS formatted datastore.

Some people have reported that they have issues with USB Datastores since ESXi 6.5. I've tried to reproduce and fix those problems. This post explains the changes in the new version and how to create VMFS 5 or VMFS6 formatted USB devices as datastore on your ESXi host. Read more »

How to use ESXCLI v2 Commands in PowerCLI

PowerCLI, a set of PowerShell extensions for vSphere, is a great tool for automating VMware configuration and management tasks. It allows you to change a lot of ESXi host and vCenter settings. A powerful cmdlet is Get-EsxCli which allows you to run ESXCLI tasks from your PowerCLI console. ESXCLI is the main configuration command on an ESXi host.

This post explains how to use the Get-EsxCli cmdlet with the new V2 interface, which is much more intuitive than the old method.


Read more »

ESXi 6.5 - ESXCLI Command Mindmap

esxcli-splashIn vSphere 6.5 the command line interface esxcli has a new namespaces and 93 new commands. Esxcli is a complete set of commands that you can use for troubleshooting, configuration or kickstart files. I have created and printed a mindmap to navigate through the namespaces more quickly. This post covers only basic namespaces, available on all ESXi 6.5 hosts. If you've installed additional software you might see more namespaces. I've also created mindmaps for ESXi 5ESXi 5.5 and ESXi 6.0.

ESXCLI in version 6.5 has 16 namespaces: Read more »

VMware vSphere 6.5 Configuration Maximums Changes

VMware vSphere 6.5 offers increased scalability. You can see a comparision against all previous verisons at my ESX and vCenter Configuration Maximums page. Changes in VMware vSphere 6.5 are:

Virtual Machine and Host Maximums

vSphere 6.5 vSphere 6.0 
RAM per virtual machine 6 TB 4 TB
Video memory per virtual machine 2 GB 512 MB
Logical CPUs per host 576 480
Number of total paths on a server 2048 1024
FC LUN ID 16383 1032
Volumes per host 512 256

vCenter Server Maximums

vSphere 6.5 vSphere 6.0
Hosts per vCenter Server 2000 1000
Powered on virtual machines 25000 10000
Registered virtual machines 35000 15000
Number of host per datacenter 2000 500
Virtual machines per cluster 8000 4000
Hosts per distributed switch 2000 1000


VMware ESXi 3.5 - 6.5 Hypervisor Size Comparison

VMwares bare-metal hypervisor ESXi is in the market for almost 9 years now. During that time it has been continuously refined and added with new features. Since vSphere 5.0, the hypervisor size is very constant and has not increased severely. In this post I am going to have a look at how much the hypervisor footprint has been changed from ESXi 3.5 to ESXi 6.5.

  • ESXi 3.5 - 46,01 MB
  • ESXi 4.0 - 59,99 MB
  • ESXi 4.1 - 85,19 MB
  • ESXi 5.0 - 132,75 MB
  • ESXi 5.1 - 125,85 MB
  • ESXi 5.5 - 151,98 MB
  • ESXi 6.0 - 154,90 MB
  • ESXi 6.5 - 135,39 MB


Read more »

New ESXCLI Commands in vSphere 6.5

esxcli-65In vSphere 6.5 the command line interface esxcli has been extended with new features. This post introduces the new and extended namespaces. Remarkable changes in esxcli version 6.5 are:

  • USB passthrough configuration
  • NVMe device status and configuration
  • VIB signature verification
  • Storage adapter capabilities
  • Device capacity information
  • VMFS6 reclaim configuration
  • vSAN iSCSI configuration
  • Physical nic coalesce queue configuration
  • WBEM configuration


Read more »