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This post is for the administrators who are more familiar with managing ESX hosts and new to  ESXi hosts. There are many environment with lot of ESX hosts and  ESXi hosts are introduced to the environment  after the vSphere 5. only ESXi will be available post vSphere 5 and ESX is discontinued. So there are many administrators who are new to ESXi management. When you tried to connect to your ESXi host directly via vSphere client as like connecting to ESX server. You may face the error message " The vSphere client could not connect to "x.x.x.x". You don't have permission to login to the server"






Don't be panic and don't try to restart your management services as all administrators do when they are not able to connect to the host via vSphere client.This above error is because of the "ESXi Lockdown Mode is Enabled" in your ESXi host.

When ESXi Lockdown mode is enabled, it will not allow any other user other than vpxuser have authentication permission and no other users can perform operations against the host directly. Lockdown  Mode forces all operations on the host to be performed through vCenter server. Root user account can be used to login to DCUI when ESXi lockdown mode is enabled.

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This post is from my website Difference between VMware ESX and ESXi ~ VMware Arena


It's been a long debate that everyone has been asked by what is the difference between ESX and ESXi. Most of the admins would have asked this question during interviews and also asked by new learners of VMware virtualization. I decided to post on the topic to give architectural difference always as to compare the different level capabilities between ESX & ESXi.
What is VMware ESX ?

ESX (Elastic Sky X) is the VMware’s enterprise server virtualization platform. In ESX, VMkernel is the virtualization kernel which is managed by a console operating system which is also called as Service console. Which is linux based and its main purpose is it to provide a Management interface for the host and lot of management agents and other thrid party software agents are installed on the service console to provide  the functionalists like hardware management and monitoring of ESX hypervisor.                                                                                                                                        

Graphic Thanks to VMware



What is VMware ESXi ?

ESXi (Elastic sky X Integrated) is also the VMware’s enterprise server virtualization platform. In ESXi, Service console is removed. All the VMware related agents and third party agents such as management and monitoring agents can also run directly on the VMkernel. ESXi is ultra-thin architecture which is highly reliable and its small code-base allows it to be more secure with less codes to patch. ESXi uses Direct Console User Interface (DCUI) instead of a service console to perform management of ESXi server. ESXi installation will happen very quickly as compared to ESX installation.


Graphic Thanks to VMware


Difference between ESX and ESXi

ESX 4.1 is the last version availability of ESX server. After vSphere 5, only ESXi is available.  This comparison based out of the VMware Article

CapabilityESX     ESXi
Service ConsolePresentRemoved
Troubleshooting performed viaService Console            ESXi Shell
Active Director AuthenticationEnabledEnabled
Secure SyslogNot SupportedSupported
Management NetworkService Console InterfaceVMKernel Interface
Jumbo FramesSupportedSupported
Hardware Montioring3 rd Party agents installed in Service consoleVia CIM Providers
Boot from SANSupported in ESXSupported in ESXi
Software patches and updatesNeeded as smilar to linux operation systemFew pacthes because of small footprint and more secure
vSphere web AccessOnly experimentalFull managenet capability via vSPhere web client
Locked Down ModeNot presentPresent . Lockdown mode prevents remote users to login to the host
Scripted InstalltionSupportedSupported
vMA SupportYesYes
Major Administration command-line Commandesxcfg-esxcli
Rapid deployment via Auto DeployNot supportedSupported
Custom Image creationNot supportedSupported
VMkernel Network Used forvMotion,Fault Tolarance,Stoarge ConnectivityManagement Network , vMotion, Fault Tolarance, Stoarge Connectivity, ISCSI port binding


This post is from blog Enable SSH and ESXi Shell for ESXi 5.1 host ~ VMware Arena


This post explain you different methods to enable SSH and ESXi shell for ESXi hosts. This demo is explained with ESXi 5.1 host. It is absolutely necessary to enable SSH or ESXi shell during troubleshooting your ESXi shell because all the troubleshooting cannot be performed via vSphere Client.  SSH and ESXi Shell can be enabled either via vSphere client or via Direct Console.


Enable SSH and ESXi Shell via vSphere client

1.Connect to your ESXi host or vCenter via vSphere client.

2.Click on Configuration tab ->Select security profile under software -> Click on Properties for services.




3.Select the service ESXi shell and click on Options



4. Select Start and stop Manually and click on Start to start the services



5. Follow the same step to enable SSH service for ESXi host. Make sure the service status is running once the service is started.




Enable SSH and ESXi Shell via Direct Console

1.Connect  to your ESXi host via remote console connections like ILO or DRAC.

2.Press F2 to login with your root credentials



3.Select Troubleshooting options -> Press Enter



4. Press Enter on "Enable ESXi Shell"  & "Enable SSH" to enable the services



5. Press Esc to logout.


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This post is from my blog post How to patch VMware ESXi 5 host using command line ~ VMware Arena

We have understood how to manually search and download the VMware ESX/ESXi patches from VMware patch download page from my previous post "Search and download VMware Patches" . This post is going to explain you how to manually install the patches on ESXi hosts using command line. This will be useful if you don't have update manager in your environment and patching to the ESX/ESXi servers in your environment requires manual intervention. I am going to explain you step by step procedure including all the pre-requisites steps to install the patches on ESXi 5.1 hosts.


Pre-requisites steps for installing ESXi patches


1. Download the patches applicable for our ESX/ESXi  version manually. I have manually downloaded 2 patches for my ESXi 5.1 host ( &


2. You can install patches using esxcli command by using SSH connection or via ESXi shell using remote console connections like ILO, DRAC. To enable SSH and ESXi Shell for your ESXi host , Take a look at my Blog post "Enable SSH and ESXi Shell for your ESXi host"


3. Now the downloaded patches needs to be transferred to the datastore of ESX/ESXi hosts. This can be done either by directly uploading the patches via datastore browser or transfer the files via winscp








4. Once file is transferred.Make sure Owner and Group have been assigned with execute permission. Right click on the transferred patch zip file in winscp and click properties. Make sure Owner and Group have been assigned with Read (R), Write (W) and execute (X) selected and click on OK.




Install Patches on ESXi host using esxcli commands

1. Login to your ESXi host using SSH or ESXi shell with your root credentials


2. Browse towards the Patch location in your datastore  and verify the donwloaded patches are alread in and note down the complete path for the patch.


cd /vmfs/volumes/datastore1/folder loctaion



3.Before installing patches placing your ESXi host in maintenance mode is very important. Please take look at my blog post "Placing ESX host in Maintenenace mode"


4. Execute the below command  to install the patch ""


esxcli software vib install -d /vmfs/volumes/datastore1/ESXi\ patches/



5.  To verify the installed VIB's installed on your host execute the below command

esxcli software vib list


6. Reboot your ESXi host for the changes to take effect and exit your host from the maintenance mode.


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This post is from my technical website


There will be difference in the view of Provisioned Storage, Non-shared Storage & Used Storage for Thick VMDK and Thin VMDK disk For Thick VMDK, All the above 3 values will be same but refer the value difference for the Thin Disk. In My case, My virtual Machine is allocated with 45 GB of disk size and Disk type is Thin.
Why Provisioned Storage in the above screenshot is showing as 53.01 GB which is not matching with the Provisioned size of VMDK which is 45 GB. This is because the Provisioned storage of 53.01 GB includes the virtual machine files like swap,vmx and log files, etc in virtual machine directory.
Not-Shared Storage:

Not-shared storage shows the space occupied by the virtual machine on the datastore space and it is not shared with any other virtual machines.
Used Storage:

Used Storage shows the space actually occupied by the virtual machine files (Config Files, Log files, VMDK & Snapshots,etc) in the Virtual Machine Directory. Value of the used storage will be changed or little more when the virtual machine is powered on because Swap files will be created in the virtual machine directory and disappeared, when VM is powered down.
Thanks For Reading!!!

This post is from my technical webiste


This post is the follow up post for my previous post on VMware HA Slot Calculation. In that post, i have explained the step by step procedure for how to calculate the HA slot information. This post clarifies more on the Total Slots, Used Slots & Available slots in VMware HA Slot calculation. I strongly recommend to read my previous post on HA slot calculation to fully understand the concepts of this post.


From the above snapshot,
Total Slots in Cluster = 234
Used Slots  = 6
Available slots  = 150
What is that? How does it calculate and our mind will think of the below calculation
Available slots = Total slot - Used slots i,e  Available slots = 234 - 6 = 228. It should come as 228 as available slots but why Available slots is 150 in the above snapshot. Is that wrong or VMware did something wrong in HA slot calculation? Absolutely NOT. Below is the method of calculation for Total Slots, Used Slots & Available slots.
Available Slots  = (Total Slots -Used Slots) - Slots reserved for failover capacity
How to Calculate Slots reserved for failover ?
It is basically coming from you Admission Control Policy of HA cluster. I have enabled admission control and configured Admission control Policy as " Host Failures Cluster Tolerates" is equal to 1 . So It will make sure the resources always be available in the cluster as a reserved capacity to tolerate the 1 ESX host failure in my 3 node HA cluster.So, It has to reserve some capacity for fail over purposes.


Lets Come back to the Calculation
Total Available Slots in the Cluster = 234
No of Hots in HA cluster = 3
Total Available slots per ESX host = 234 /3 = 78 Slots Per Host
"Host Failures Cluster Tolerates" Admission control Policy = 1 host Failure. So, 1 host failure should be tolerated in the cluster by reserving 78 Slots for fail over purposes.
Available Slots  = (Total Slots -Used Slots) - Slots reserved for fail over by admission control policy
Available Slots  = (234 - 6)  - 78
Available Slots  = 150 Slots
I hope this post will clear doubts regarding Total Slots, Used Slots & Available slots in VMWare HA slot calculation. If you are looking for more information on Admission Control policy, Please visit my blog post on HA interview questions.
Thanks For Reading!!!!

This blog post if from my techincal webiste



Most of the times, I find difficulty to understand the Performance metrics of Virtual Machine displayed in the vCenter at my initial stages of learning. But Now I believe that got little bit understanding. This post is for to help  the VMware beginners to understand Virtual Machine Performance metrics. Understanding the Performance metrics of virtual Machine is extremely useful  to troubleshoot the virtual Machine Performance issues.


There are 2 Places Where we can check the Performance metrics of Virtual Machine in vCenter Server


1. Summary Tab of Virtual Machine
2.Resource Allocation Tab of Virtual Machine


Let's Take a detailed look of each virtual machine performance metrics.


Below Snapshot is the general overview about the Virtual Machine and its allocated resources. My virtual Machine has allocated with 1vCPU and 4096 MB (4 GB) of Memory



Memory Overhead  (164.47 MB)
ESX Hosts requires some amount of Memory as Memory Overhead to run this virtual Machine workload like Virtual Machine frame buffer and Mapping table etc.In our case, ESX requires 164.47 MB memory overhead to run this virtual machine in addition to the Configured memory of 4 GB.



Consumed Host CPU   26 MHZ


Consumed Host CPU is the amount of ESX server's CPU consumed by the virtual Machine

Consumed Host Memory   2057.00 MB
Consumed Memory is the amount of ESX server's physical memory consumed by the virtual

machine and this value also includes the Memory overhead for this virtual machine.Consumed Host Memory displays the highest amount of memory used by that VM in other words touched memory. Generally, Windows Operating system will touch almost all the memory assigned to that virtual machine during boot time.

Active Guest Memory  204.00 MB

Active Guest Memory is the amount of memory that VMkernel believes that it has been actively used by virtual machine.

Provisioned Storage , Non-Shared Storage & Used Storage
Resource Allocation Tab of Virtual Machine - Memory

Host Memory




Consumed  (2.01 GB)

Consumed is the amount of ESX server machine memory currently allocated to this virtual Machine. Out of 4 GB of Configured Memory, 2.01 GB is being consumed by our virtual Machine

Overhead Consumption  (109.00 MB)

Overhead Consumption is the amount of memory consumed for the Visualization overhead to run this particular virtual machine

Guest Memory

Private Guest Memory (1.09 GB)

Private memory is the amount of memory that is physically backed by the Host.Private memory is calculated using the below formula


Private memory = VM Allocated Memory  – Unaccessed Memory – Shared Memory


Private Memory = 4 GB - 84.00 MB - 2.01 GB

Shared Guest Memory (2.01 GB)
Shared Guest Memory is the amount of memory which is shared through the TPS (Transparent Page sharing) one of the memory management Technique of ESX server.This value also includes the memory shared with other Virtual Machines and  shared within the Virtual Machine.
Swapped Memory  (0 MB)
Swapped Memory is the amount of guest Physical memory swapped out to the Virtual Machine's swap device by the ESX kernel (VMkernel). This value refers to the VMkernel swapping not the Guest operating system swapping activity.
Ballooned  (0 MB)

The Balloon memory is the amount of guest physical memory that is currently reclaimed through the balloon driver (vmmemctl). This is carried out by one of the Memory management technique of ESX server named Memory Ballooning.

Unaccessed (84.00 MB)

Unaccessed memory is the  current amount of memory not being accessed by the Virtual machine (free memory for the guest)

Active (122.0 MB)

Active Guest Memory is the amount of memory that it has been actively used by the virtual machine.

Resource Settings


Reservation  (0 MB)

Reservation is the minimum amount of memory guaranteed to the virtual Machine. At any cost, That particular virtual machine always assigned the reserved memory. We dont have memory reservation configured for our virtual machine so, the value displayed above is 0 MB.
Limit  (unlimited)
Limit is just opposite to the Reservation. Limit is the upper cap of the virtual machine memory. If the virtual machine is configured with 4 GB of memory but memory limit is set as 3 GB. Virtual machine cannot use memory more than 3 GB. This is the upper cap limit of memory. For our Virtual machine, we didn't configured memory limit so it is displayed as unlimited.
To configure Memory reservation and Limit, Go to Virtual Machine -> Edit Settings -> Resources Tab -> Memory
Move the slider towards right side to configure reservation and Un-check the unlimited to specify the memory limit.
Configured  (4 GB)
Configured  memory is the total amount of memory configured for the virtual machine.
Shares  (Normal)
Shares determine the relative weight of virtual machine among its siblings i.e other virtual Machines in same ESX host or Resource pools.If a virtual Machine has more memory shares as compared to the other virtual machines in same ESX host or in resource pool, it is entitled to receive more resources, when the virtual machines are competing for memory resources in case of contention.
You can see the share value of each virtual Machine by going to resource allocation tab of cluster or Resource Pool
There are 3  different types of share value
3. Low
The ratio between is Share value of  High:Normal:Low is 4:2:1. You can use the same method which used to configure Reservation and Limit to change the share value of virtual machine too.
Worst Case allocation  (4.17 GB)
Worst case allocation is the amount of memory that virtual machine can allocate When all the virtual Machines in the ESX or Cluster consumes its full amount of its configured or allocated resources. This is the Value of memory the VM will get in this scenario.
Overhead reservation  (176 MB)
This is the amount of memory reserved for the Virtualization overhead for this virtual Machine.
Thanks For Reading !!!!

The below post of from my techical website

VLAN Tagging in ESX (VST,EST & VGT)


I am getting lot of questions on different types of VLAN tagging and how it works and how to configure it and they are even wondering that there is no specific setting named "VLAN tagging" in vsphere host network settings. Let's cover from the basics..


There are 3 types of VLAN tagging avaliable in Vsphere.


1.Virtual Switch Tagging (VST)
2.External Switch Tagging (EST)
3.Virtual Guest Tagging (VGT)


There is no specific settings named "VLAN Tagging" is avialable in the vpshre host network settings. VLAN tagging is  determined by the VLAN value specified at the port group and it tells the vswitch or Phyiscal switch or Virtual machines to how to handle the VLAN tagging.


1. Virtual Switch Tagging (VST)


1.1 VST uses 802.1q VLAN trunks and tagged traffic.
1.2 VLAN tagging for all packets is performed by the Virtual Switch before leaving the ESX/ESXI host
1.3 Port groups on the Virtual switch of ESX server should be configured with VLAN ID (1-4094)
1.4 vSwitch responsibilty is  to strip off the vlan tag and send packet to virtual machine in corresponding port group.
1.5 Reduces the number of Physical nics on the server by running all the VLANs over one physical nic. Better solution would be keep 2 nics for redundancy.
1.6 Reduces number of cables from ESX server to physical switch.
1.7 The physical switch port connecting the uplink from the ESX should be configured as Trunk port.
1.8 virtual machine network Packet is delivered to vSwitch and before it is sent to physical switch the packet is tagged with vlan id according to the port group memebership of originating virtual machine.




2.External Switch Tagging (EST)


2.1  In EST, ESX host doesn't see any vlan tags and does not handle any VLAN tagging.

2.2  All the tagging operation is done by physical switch and virtual switch is not aware about that.

2.3  Number of physical nics = no of VLANs connected to ESX

2.4  Port groups on the Virtual switch of ESX server need not to be configured with the VLAN number or configure VLAN ID 0 (if it is not native VLAN)

2.5  Count of NICS and cable connected to ESX is more as compared to VST approach.

2.6  The physical switch port connecting the uplink from the ESX should be configured as Access port assigned to specific VLAN.

2.7  virtual machine network Packet is delivered to physical switch without any tagging operation performed by the virtual switch.





3. Virtual Guest Tagging (VGT)


3.1 you must install 8021.Q VLAN trunking driver instide virtual machine guest opearting system.

3.2 All the VLAN tagging is performed by the virtual machine with use of trunking driver in the guest.

3.3 VLAN tags are understandable only between the virtual machine and external switch when frames are passed to/from virtual switches.

3.4 Virtual Switch will not be involved or aware of this operation. Vswitch only forwards the packets from Virtual machine to physical switch and will not perform any operation.

3.5 Port group of the virtual machine should be configured with VLAN ID 4095

3.6 The physical switch port connecting the uplink from the ESX should be configured as Trunk port



Below is comparison table for the people want a comparison under single table



I hope it will be helpful to understand the concept of VLAN Tagging with the simple language. Happy reading.....!!!!!!!