I decided to write this short post because talking with customers I still listen a lot of people say that esxi is nothing more than the free version of vmware hypervisor….. once and for all: IT IS NOT’ SO!!!!
Start by saying that from version 5 of vSphere exists ONLY esxi so it is not for sure “the free version”. We add that esxi exists one and only one version, and based on the inserted serial it enables or not its functionality.
Just installed esxi is in TRIAL/EVALUATION version and allows you to use all the features of the hypervisor for 60 days. After 60-day trial license ends and almost all the functionalities are blocked, first of all you can no longer start the vms… which makes your esxi little useful (the powered on vms continue to work).
At this point you can decide to purchase a license or get a free license.
For the paid license you can get a standard, or an enterprise or an enterprise plus (obviously what changes, as we said before, are the features that are enabled); There are also kits that include a certain number of licenses in one package at a cheaper cost. An important thing to remember is that hosts must be licensed for socket number.
You can get the serial for free license for free (there is a reason why it's called free!) by registering on vmware.com, regarding the limits of the used features, there have been changes in the various versions eg. the 5 and 5.1 had limits of physical usable ram, limit which has now been removed with the 5.5 (you find it written eg. HERE). The biggest limits of a free host are the fact that obviously can not be managed by a vcenter and that there are no enabled features to manage backups, which means that you'll never be able to efficiently backup the vms that run on it via backup software that rely on virtualization (ok you can backup them as if they were physical machines, it is still uncomfortable), There is also a script created by the community which is called ghettoVCB that allows you to backup the vms but is very limiting and not very powerful.
Ok we talked about esxi….. and then what the hell is esx?!!??! Said briefly esx is the old version of the hypervisor and the main difference is that the current esxi, besides being a bare-metal hypervisor exactly as esxi, it also contained a service console that was a linux machine which can directly access the HW and through which we managed a number of management features. The service console has been removed to shrink (and much!) the size of the hypervisor that has gained so in slenderness (I can install it on a USB stick or on a 1 GB internal sd, 2 is better), in security (less code = less bugs) and amount of patches to manage to ensure security and reliability.
Here you will find some official FAQ who can make you better understand
Spero di aver chiarito un pò le idee 🙂