Table of contents

SSH Connection with Putty

How to enable SSH login for a root user in VMware ESX

How to work with VMware snapshots using the GUI

VMWare Interview Questions & Tips

1. VMWare Kernel is a Proprietary Kenral and is not based on any of the UNIX operating systems, it's a kernel developed by VMWare Company. 
2. The VMKernel can't boot it by itself, so that it takes the help of the 3rd party operating system. In VMWare case the kernel is booted by RedHat Linux operating system which is known as service console. 
3. The service console is developed based up on Redhat Linux Operating system, it is used to manage the VMKernel 
4. To restart webaccess service on vmware service vmware-webaccess restart – this will restart apache tomcat app 
5. To restart ssh service on vmware service sshd restart 
6. To restart host agent(vmware-hostd) on vmware esx server service mgmt-vmware restart 
7. Path for the struts-config.xml /usr/lib/vmware/webAccess/tomcat/apache-tomcat-5.5.17/webapps/ui/WEB-INF/ 
8. To start the scripted install the command is    esx ks=nfs:111.222.333.444:/data/KS.config ksdevice=eth0               location                                             device name 
9. Virtual Network in Simple……………….        Virtual Nic(s) on Virtual Machine(s) ----->         Physical Nic on the ESX Server (Virtual Switch - 56 Ports)  ----->            Physical Switch Port              Should be trunked with all the VLANS to which the VM's need access  All the ESX servers should be configured with Same number of Physical Nics (vSwitches) and Connectivity also should be same, So that vMotion succeeds All the Virtual Machines are connected to one vSwitch with Different VLANS, this means the Physical Nic(vSwitch) needs to be trunked with the same VLANS on the Physical Switch Port 
10. What are the three port groups present in ESX server networking  1. Virtual Machine Port Group - Used for Virtual Machine Network   2. Service Console Port Group - Used for Service Console Communications   3. VMKernel Port Group - Used for VMotion, iSCSI, NFS Communications 
11. What is the use of a Port Group?     The port group segregates the type of communication. 
12. What are the type of communications which requires an IP address for sure ?        Service Console and VMKernel (VMotion and iSCSI), these communications does not happen without an ip address (Whether it is a single or dedicated) 
13. In the ESX Server licensing features VMotion License is showing as Not used, why?    Even though the license box is selected, it shows as "License Not Used" until, you enable the VMotion option for specific vSwitch 
14. How the Virtual Machine Port group communication works ?     All the vm's which are configured in VM Port Group are able to connect to the physical machines on the network. So this port group enables communication between vSwitch and Physical Switch to connect vm's to Physical Machine's 
15. What is a VLAN ?     A VLAN is a logical configuration on the switch port to segment the IP Traffic. For this to happen, the port must be trunked with the correct VLAN ID 
16. Does the vSwitches support VLAN Tagging? Why?      Yes, The vSwitches support VLAN Tagging, otherwise if the virtual machines in an esx host are connected to different VLANS, we need to install a separate physical nic (vSwitch) for every VLAN. That is the reason vmware included the VLAN tagging for vSwitches. So every vSwitch supports upto 1016 ports, and BTW they can support 1016 VLANS if needed, but an ESX server doesn’t support that many VM’s. :)   
17. What is Promiscuous Mode on vSwitch ? What happens if it sets to Accept?     If the promiscuous mode set to Accept, all the communication is visible to all the virtual machines, in other words all the packets are sent to all the ports on vSwitch     If the promiscuous mode set to Reject, the packets are sent to inteded port, so that the intended virtual machine was able to see the communication. 
18. What is MAC address Changes ? What happens if it is set to Accept ?When we create a virtual machine the configuration wizard generates a MAC address for that machine, you can see it in the .vmx (VM Config) file. If it doesn't matches with the MAC address in the OS this setting does not allow incoming traffic to the VM. So by setting Reject Option both MAC addresses will be remains same, and the incoming traffic will be allowed to the VM. 
19. What is Forged Transmits ? What happens if it is set to Accept ?  When we create a virtual machine the configuration wizard generates a MAC address for that machine, you can see it in the .vmx (VM Config) file. If it doesn't matches with the MAC address in the OS this setting does not allow outgoing traffic from the VM. So by setting Reject Option both MAC addresses will be remains same, and the outgoing traffic will be allowed from the VM. 
20. What are the core services of VC ?  VM provisioning , Task Scheduling and Event Logging 
21. Can we do vMotion between two datacenters ? If possible how it will be? Yes we can do vMotion between two datacenters, but the mandatory requirement is the VM should be powered off. 
22. What is VC agent? and what service it is corresponded to? What are the minimum req's for VC agent installation ?  VC agent is an agent installed on ESX server which enables communication between VC and ESX server.The daemon  associated with it is called vmware-hostd , and the service which corresponds to it is called as mgmt-vmware, in the event of VC agent failure just restart the service by typing the following command at the service console          " service mgmt-vmware restart "VC agent installed on the ESX server when we add it to the VC, so at the time of installtion if you are getting an error like " VC Agent service failed to install ", check the /Opt size whether it is sufficient or not 
23. How can you edit VI Client Settings and VC Server Settings ? Click Edit Menu on VC and Select Client Settings to change VI settings Click Administration Menu on VC and Select VC Management Server Configuration to Change VC Settings 
24. What are the files that make a Virtual Machine  ?     .vmx - Virtual Machine Configuration File     .nvram - Virtual Machine BIOS     .vmdk - Virtual Machine Disk file     .vswp - Virtual Machine Swap File     .vmsd - Virtual MAchine Snapshot Database     .vmsn - Virtual Machine Snapshot file     .vmss - Virtual Machine Suspended State file     .vmware.log - Current Log File     .vmware-#.log - Old Log file 
25. What are the devices that can be added while the virtual Machine running In VI 3.5 we can add Hard Disk and NIC's while the machine running. In vSphere 4.0 we can add Memory and Processor along with HDD and NIC's while the machine running 
26. How to set the time delay for BIOS screen for a Virtual Machine? Right Click on VM, select edit settings, choose options tab and select boot option, set the delay how much you want. 
27. What is a template ? We can convert a VM into Template, and it cannot be powered on once its changed to template. This is used to quick provisioning of VM's. 
28. What to do to customize the windows virtual machine clone,? copy the sysprep files to Virtual center directory on the server, so that the wizard will take the advantage of it. 
29. What to do to customize the linux/unix virtual machine clone,? VC itself includes the customization tools, as these operating systems are available as open source. 
30. Does cloning from template happens between two datacenters ? Yes.. it can, if the template in one datacenter, we can deploy the vm from that template in another datacenter without any problem. 
31. What are the common issues with snapshots? What stops from taking a snapshot and how to fix it ? If you configure the VM with Mapped LUN's, then the snapshot failed. If it is mapped as virtual then we can take a snapshot of it. If you configure the VM with Mapped LUN's as physical, you need to remove it to take a snapshot. 
32. What are the settings that are taken into to consideration when we initiate a snapshot ? Virtual Machine Configuration (What hardware is attached to it) State of the Virtual Machine Hard Disk file ( To revert back if needed) State of the Virtual Machine Memory (if it is powered on) 
33. What are the requirements for Converting a Physical machine to VM ? An agent needs to be installed on the Physical machine VI client needs to be installed with Converter Plug-in  A server to import/export virtual machines 
34. What is VMWare consolidated backup ? It is a backup framework, that supports 3rd party utilities to take backups of ESX servers and Virtual Machines. Its not a backup service. 
35. To open the guided consolidation tool, what are the user requirements ? The user must be member of administrator, The user should have "Logon as service" privileges - To give a user these privileges, open local sec policy, select Logon as service policy and add the user the user should have read access to AD to send queries

commands useful for an admin

These are some of the commands useful for an admin

date --- this is only option available to set time/date
hwclock --- to sync the time to software clock/hardware clock
Esxcfg-vswitch -- virtual switch configuration ., be clear abt port groups
esxcfg-vswif -- service console in the esx server
esxcfg-vmnics-- for setting the speed/mode of operating
esxtop --- to see the performance of esx server
esxupdate -l query -- to see the packages are installed on esx
/etc/sysconfig/network --- to see the network configuration
/etc/passwd -- to see the user accounts
/etc/ssh -- for ssh login properties



Few ESX Commands ** Important Log and their location
===========================================
vmkping - use vmkernel to ping a device
esxcfg-vswif for configuring network interface
vm-support to run diagnostic commands
esxupdate -l query query patches installed on ESX Server
esxcfg-rescan vmhba1 to rescan HBA’s
ps -ef | grep hostd To check hostd is running
esxcfg-mpath -l to list path details
________________________________________
Important Log and their locations

VMKernel Logs = > /var/log/vmware/
VIClient logs = > /var/log/vmware/hostd.log
Virtual Center interaction logs = > /var/log/vmware/vpx/vpxa-*.log
VMWare Patch activity logs = > /var/log/vmware/esxupdate.log
[root@esx2007a config]# cat vmware-sites
FULLTIME_SITES_TID 00000061
+ 1:8042,8042,8043 esx2007e vmware #FT_Agent_Port=8045
+ 2:8042,8042,8043 esx2007d vmware
+ 3:8042,8042,8043 esx2007b vmware
+ 4:8042,8042,8043 esx2007a vmware
+ 5:8042,8042,8043 esx2007c vmware
License server logs = > %ALLUSERSPROFILE%\Application Data\VMware\VMware License Server\lmgrd.log

commands for N/W config via console

here is few commands for N/W config via console

esxcfg-vswitch -a vSwitch0
esxcfg-vswitch -L vmnic0 vSwitch0
esxcfg-vswitch -A "Service Console" vSwitch0
esxcfg-vswitch -v "vlanno" -P "Service Console" vSwitch0
esxcfg-vswif -a vswif0 -i X.x.x.x -n x.x.x.x -p "Service Console"
esxcfg-vswitch -l
esxcfg-vswif -l
esxcfg-nics -l
esxcfg-vmknic -l