For exaple as I understand it Hyper-V enables dynamic memory allocation, something that ESXI does not.
ESXi Does not need Dynamic memory allocation. ESXi runs each virtual machine as its own process, meaning each virtual machine will only occupy as much of the hosts memory as It actually physically uses via the standard Linux memory scheduler. This means you can over-allocate a server without consequence (although if you run out some of your hosts will thrash). I have attempted to use dynamic memory allocation in test environments at work for clients, but it usually leads to bluescreens (Likely the fault of whoever wrote PERC storage controller drivers, which enjoy eating host memory without letting the OS know).
Hyper-v on the other hand, operates much like an IBM LPAR. The host system itself is actually a virtual machine, and the virtual machines are all run in parallel to that. Which means you can only statically assign memory. All dynamic memory allocation does is dynamically change the static assignment
Also, why does people think running off a thumb drive is an advantage. Cool, yes; advantage, I don't see it.
Bare-metal ESXi is designed to load itself into the memory of the system. ESXi only performs I/O operations when you make settings changes or writes logs, literally everything else is stored in memory. This makes the lives of sysadmins in server farms a lot easier since most hypervisor-purposed servers have an internal USB port. It also allows to run the servers completely disk-less with all RAID/SATA functions disabled.
And if one ever fails (not that I have ever seen one fail) Just DD the ESXi image onto a new flash drive, replace, and go.
Edited by darkside34, 16 April 2012 - 01:41 PM.