As I said earlier this week, VMware memory management is still a topic which a lot of VMware administrators don’t understand.
Tuesday I discussed the virtual machine memory allocation graphs. Today we will deal with VMware vSphere uses transparent page sharing (TPS), memory compression, host swapping and ballooning.
VMware ESXi, a crucial component of VMware vSphere 5.0, is a hypervisor designed to efficiently manage hardware resources including CPU, memory, storage, and network among multiple, concurrent virtual machines. In this article I will describes the basic memory management concepts in VMware ESXi and describe the performance impact of these options.
ESXi uses several innovative techniques to reclaim virtual machine memory, which are:
- Transparent page sharing (TPS)—reclaims memory by removing redundant pages with identical content;
- Ballooning—reclaims memory by artificially increasing the memory pressure inside the guest;
- Hypervisor swapping—reclaims memory by having ESXi directly swap out the virtual machine’s memory;
- Memory compression—reclaims memory by compressing the pages that need to be swapped out.
So how does it work.