CLONE, TEMPLATE, OVF, VAPS, SNAPSHOTS

What is cloning:- A clone is an exact copy of an existing virtual machine. 

What is Snapshot- A snapshot is a point in time check points of a VM with all its configuration settins disk states and memory contains . We can return back to that point in time check point or image stage at any time.

Is cloning a running VM possible-  Yes

Linked Clone-A linked clone is a copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation. It is made of parent VM's snapshot. It needs continuous access to its parent VM' and is disabled if access to parent VM fails. Linked clone have some performance issues than a full clone VM. 

What is customization specification- While cloning a VM you can also customize VMs, ensuring that each VM is unique. This VM customization information can be saved and used over and over again.

What is Sysprep-This is a native windows tool that can be used in VMware also. The purpose of the tool is to allow for a single Windows installation to be cloned many times over and over, each time with an unique  identity (new computer name, new IP address, and new Security Identifier (SID). From windows 2008 onwards VMware does not need this tools

How to customize windows VM clone-Copy Sysprep tool to a specific directory in vCenter server so that customization wizard can take advantage from it. From windows vista onwards this tool is built in to windows.

Ex- C:\document and settings\All users\Application Data\VMware\VMware VertualCenter\sysprep

How to customize Unix or linux VMs- vCenter has inbuilt customization tools because these software’s are open source.

What is Template-By creating templates, you ensure that your VM’s master image doesn’t get accidentally changed or modified. It is because you can’t start the template as a VM and can’t make any changes to it.

What is “Clone to Template”- Copies source or initial VM to a template format, leaving the original VM intact

What is “Convert to Template”-  This process takes the source or initial VM and changes it to a template format. Thus it removes the ability to turn on the VM without converting it back to a VM format. 

Why “Convert To Template” command is grayed out- Because the VM is currently powered on.

Customizing the VM template possible-No. templates can’t be powered on, and guest OS customization requires that the VM be powered on.

Does cloning from template happens between 2 datacenter-Yes

What is OVF Template- Open Virtualization Format (OVF) is a standard format for describing the configuration of a VM along with the data in the VM’s virtual hard disk.

What IS “Transient” IP allocation policy while deploying OVF- It sets the IP address of a guest OS using a ‘script’ or an ‘executable application.

What are the OVF format available?-

Folder of file

Single files OVA.

The Folder Of Files:-This format puts the integrity checking manifest (.MF) file, the structural definition (.OVF) file, and the virtual hard disk (.VMDK) file — as separate files in a folder.

Single File (OVA) format:- This format combines those separate components (.MF,.OVF,.VMDK) into a single file.

What are the different files that make up an OVF Template-

.mf or Manifest file:- contains SHA-1 digests of the other two files. Used For OVF’s integrity checking

.ovf or OVF descriptor:- XML document that contains information about the OVF template, such as product details, virtual hardware, requirements, licensing, a full list of file references,

.vmdk or virtual hard disk file:- it may contain multiple VMDK files, all of which would need to be referenced in the OVF descriptor file

What is OVA- OVF templates can also be distributed as a single file for easy distribution? This single file ends in .ova and is in zipped TAR format. .Ova means Open Virtualization Appliance.

What is VAPP- vSphere vApps leverage OVF as a way to combine multiple VMs into a single administrative unit. When the vApp is powered on, all VMs in it are powered on, in a sequence specified by the administrator. The same goes for shutting down a vApp. vApps also act a bit like resource pools for the VMs contained within them.

Remember:- You can create a vApp inside other vApps, but you can’t create a vApp on a cluster that does not have vSphere DRS enabled.

What is P2V and V2V migration- VMware offer a stand-alone product called VMware Converter. VMware Converter provides both P2V functionality as well  as virtual-to-virtual (V2V) functionality.

What are the common issues in snapshot regarding RDM or mapped LUN’s?

If you configure the VM with mapped LUNs (Physical mode RDM) then the snapshot fails. If it is mapped as virtual (Virtual mode RDM which uses a VMDK mapping file to access raw LUN) then we can take snapshot from it. So to take a snapshot of a VM which uses physical mapped LUNs you must remove the LUN?

Differences between a clone and a template?

No	Clones	Templates
1	Clone creates an exact copy of a running virtual machine at the time of cloning process.	Template act as a baseline image with a predefined configuration as per organization standard.
2	VM clones are best suited in test and development environments where you create test and work with exact copies of a production server without disturbing the production server.	Template are best suited for production  environments where you want mass distribution of a baseline virtual machine along with the installed OS, standard security policy and basic software. Once the VMs are deployed then you can configure other specific software installation and configuration task
3	Cloned virtual machine can be powered on	Templates can’t be powered on.
4	Clone virtual machine can be edited.	Template can’t be edited.
5	VM clones are not suited for mass deployment of virtual machine.	Templates are best suited for mass deployment of virtual machine.