MCS (Machine Creation Services)

1 - Adminstrator configure a VM with the App's and settings that they require to be unique for all of the planned VMs.

2 - The final image is a .vmdk virtual disk file that resides in a folder on the root of the datastore it is deployed to

3 - Admin defines the size of vm,  vcpu , memory via the MCS Wizard

4 - Admin chooses amount of vms to be created and added to catalog in the MCS Wizard

5 - Admin chooses a naming convention for the machines to be created in the catalog, in the MCS Wizard

6 -VMs are all created as "Linked Clones"

7 -Each VM created has two or three disks assigned to it:

Master image - single base disk .vmdk file - mounted as non persistent on SCSI 0:0 to each VM. allows RO to base .vmdkand all data changes are redirected to a .REDO file in the VM's home folder.

Personality Disk - A small 16MB VMDK mounted on SCSI 0:1.This contains some basic info such as machine name, SID, Domain Computer account password and other unique info injected into the OS on boot-up

Personal vDisk (Optional) This disk is used in cases where you want persistence in your VM

The time line for all of this is as follows:

1 - MCS takes a VMwaresnapshot of the Master VM

2 - MCS creates a Temp VM (XD Temp 4)which is configured with the vmdk form the original master image that was has just has a snapshot.

3 - It then clones the Temp VM (XD-Temp-4) to anohter VM, using some name supplied in he creation wizard and then appends "-baseDisk-datastore-51 to it. The VM is created with this name so that the folder and basedisk.vmdk inside have the naming convention specified in MCS

4 -After cloning, the new VM with the appended (-basedisk...) name, it is reconfigured to have the disk removed.

5 - MCS issues a command to delete the VM By first removing the disk from the VM, it prevents the base disk .vmdk and folder from being deleted when the VM is deleted. The result is that all of the VM files are purged but the base disk is still there, as well as the description name selectled in the MCS wizard.

6 - A new VM is then created called "Preparation"-+ the name specified in MCS wizard
This prep VM is created with the amount of CPU and ram specified in mcs wizard

7 -The new prep VM is reconfigured to add our basedisk created in earlier steps. Unlike all linked clones that will be created the VMDK is NOT mounted as independent: non-persistent. The contents of the base disk still need to alter to make it suitable for multiple MCS linked clones though.

8 -The prep VM is reconfigured again and the 2nd VMDK is added. This time, the .VMDK file added is a small disk file called "prepare-identify.vmdk" The file is provisioned as 16MB but is only 16KB and holds a simple file structure with a couple of files to be used for preperation process

9 -The prep VM is powered on. 

10 -After power on, it is prepared with the information found in the identifty disk:
The OS and office installations are Re-armed so that each MCS linked clone created later is ready to run with their own custom identify files

11 -After the "in guest" processing of the powered on prep VM has completed onthe prep VM, the VM is shtudown from within the guest (So a power off command will not shown in the logs)

12 -Once powered off, it is reconfigured to remove the base disk (to prevent deletion)

13 -After reconfiguration completes, the prep VM is deleted from disk
at this point, the base disk is left behind and has now been prepped and ready to be a read-only disk that all mcs linked clones will mount as their C: drive

14 -Next the VMs are created 3 at a time, using the naming convention stated in MCS wizard.

15 -After creating the VMs they are reconfigured 3 times each:

 First reconfig- VMs are sized according to the specs in the wizard

 Second reconfig- the base disk .vmdk is mounted in the VM SCSI0:0 in "Independent-non persistent" mode (RO) this is to prevent changing/locking the base disk and all write activity is redirected to a REDO file in the VMs home folder,
 
Third reconfig - A small 16mb Id disk is added similar to the one added to preparation VM.  The disk is placed in the home folder of the VM and is named %VMNAME%-IdentityDisk.vmdk". the contents of the ID disk are at the heart of what allows machines created iwth mcs to be non-persistent linked clones that can have their master disk updated, yet still persist and keep an idenity on the network]

16 -The process is repeated for 3 VMs concurrently until the total number of VMs specified in the MCS wizard is reached