Shares are only enforced during times of contention, and define relative priority. Understand their operation in VMware vSphere 6.
- [Voiceover] In this video I'll explain…how shares can be used to control resource contention.…Shares define the relative priority…of virtual machines as they compete for resources.…When you allocate CPU and memory to a virtual machine,…you're not guaranteeing it any physical resources.…CPU instructions are scheduled…on a physical processor is needed.…Memory is thin provisioned.…So shares are used to control…which virtual machine gets priority access…to those shared resources.…
Shares are only enforced during times of contention.…This is different from reservations and limits…which are enforced at all times.…This approach is beneficial because it means…that even a low priorty virtual machine…can have all the resources it needs…as long as those resources on the ESXi host…are not constrained.…Let's take a look at an example on how shares work.…Here we see an ESXi host…with two gigabytes of available memory.…And now we start to boot up virtual machines on this host.…
Notice the resource allocations of these virtual machines.…
VMware Certified Instructor Rick Crisci provides an overview of vSphere resource controls—shares, limits, and reservations—and their impact on performance and VSWP file size. Rick explains exactly what happens when virtual machines compete for resources, the role of swap files, and how resource controls help automate allocation.
In chapter 2, Rick shows how to manage performance with resource pools, including child pools. He explains the impact a reservation has on resource pools, and includes a demo on creating and configuring a resource pool. Chapter 3 is an overview of the vFlash architecture for leveraging SSD resources. Watch this chapter to learn how to configure vFlash reservations and to assign a reservation to a VM.
Note: This course maps to the Administer and Manage vSphere 6.x Resources domain of the vSphere Certified Professional 6—Data Center Virtualization (VCP6DCV) exam.
- Allocating memory and CPU
- Using ESXTOP
- Configuring reservations, limits, and shares
- Managing performance with resource pools
- Creating child and tiered resource pools
- Leveraging SSD resources with vFlash