VCP5: Memory Reservations

Understanding entitlements ,and in this case memory reservations, is a key concept to pass the VCP5 exam, although this concept is easily grasped by most people, the exam presents questions regarding these subjects in ways that will have you thinking hard. Remember entitlements are not only configured in one location. Knowing these locations and the optional settings you could configure is need-to-know information. As some starting points, know what memory reservations, limits, and shares are and HOW THEY ARE DIFFERENT. Also, know where you can set memory entitlements. Below are a few screen shots to show you where you can set them:

All entitlements including disk and cpu can be set by right clicking any VM and navigating to the "Resources" tab:

Take note of the check box in the top right corner, "Reserve all guest memory (All locked)". This can be a super helpful component if you have a VM that is key to day to day operations and should always be guaranteed all of its memory, this is where you would configure that setting. Essentially, selecting this option removes the amount of RAM assigned to the VM from the pool of resources available to all other VMs, just as other reservations do for a specified amount of memory.

This next screenshot is the "Resources" page when you select to edit the settings of a vApp. If you dont know much about vApps I suggest you go here and read up on them in the vSphere Documentation Center, but basically a vApp is a container for housing VMs that are components of maybe a single application, like for instance, a web server, a database and an application server could be in a vApp for ease of management because they are all related to a certain application. Within a vApp you can power on and off the VMs in the vApp in a particular order in one click and you can control the resources of a vApp.

Here is a screen shot about memory entitlements in vSphere from the Documenation Center if you are looking for some quick reading.