How to move your mail infrastructure away from Lotus Notes

Wednesday, 7 January 2015

Setting up a BT mail migration lab - Part 3 - VMware "best practices"

My VMware "best practices"

I am not a VMware expert. These are my settings I am using to build the labs.

The main considerations for Labs are:-

  • Robust, recoverable, reusable and flexible
  • Small VM's with big disks - Contradiction in terms
  • Naming conventions 
There are a few things that can help here and they are Snapshots and Clones.

Snaphsot takes a errrr, snapshot of the state of the machine so you can return the machine to this state. This is useful if you mess up and it is easier to go back to a snapshot. Here is the catch: As you go back to a snapshot you loose what you have just done and that can be annoying.  For example, you want to set up a training Lab where students get to a "virgin" machine and needs to install complex software. 50% of the class will simply fail as they are on the phone, or surfing etc. It would be nice to pre-install the software, take a snapshot, before and after, and then simply revert to the before snapshot. Can you then revert back to the "after snapshot" where the software has been installed?  No.

Linked Clones are interesting though. A linked clone is a snapshot that can be altered at will. It uses most of the files from the master but the clone does not effect the master. That means that a clone is really tiny but fully functional, if the Master is where it is suppose to be.

The Linked Clone takes the exact settings from the master. If your master is 60GB and 2GB of memory then the clone will be the same. This is helpful in a Lab environment. For the above scenario you can can spin two clones of the master and on one install the software and the other can be mangled by the students. Afterwards you just power down the mangled clone.

Note the Custom adapters.

Just to show what I mean:-

The difference in size is huge. Please keep in mind that they are linked and that as you work on the clone the disk space will increase.

Word of warning though: If your master VM gets corrupted or moved you are dead in the water. 

Hint: Also remember, once the machines are built you can use VMware Player to use them! This is perfect for people without a license.


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