Explanation/Reference:
Explanation:
With the Dynamic Memory improvements for Hyper-V in Windows Server 2012, you can attain higher consolidation numbers with improved reliability for restart operations. This can lead to lower costs, especially in environments that have many idle or low-load virtual machines, such as pooled VDI environments. Dynamic Memory run-time configuration changes can reduce downtime and provide increased agility to respond to requirement changes.
Dynamic Memory, introduced in Windows Server 2008 R2 Service Pack 1 (SP1), defined startup memory as the minimum amount of memory that a virtual machine can have. However, Windows requires more memory during startup than the steady state. As a result, administrators sometimes assign extra memory to a virtual machine because Hyper-V cannot reclaim memory from these virtual machines after startup. In Windows Server 2012, Dynamic Memory introduces a minimum memory setting, which allows Hyper-V to reclaim the unused memory from the virtual machines. This is reflected as increased virtual machine consolidation numbers, especially in Virtual Desktop Infrastructure (VDI) environments.
Windows Server 2012 also introduces Smart Paging for reliable virtual machine restart operations.
Although minimum memory increases virtual machine consolidation numbers, it also brings a challenge. If a virtual machine has a smaller amount of memory than its startup memory and if it is restarted, Hyper-V needs additional memory to restart the virtual machine. Due to host memory pressure or virtual machine states, Hyper-V may not always have additional memory available. This can cause sporadic virtual machine restart failures. Smart Paging is used to bridge the memory gap between minimum memory and startup memory, and allow virtual machines to restart reliably.
References: http://technet.microsoft.com/en-us/library/jj612868.aspx