vFlash Reservations are used to guarantee Flash resources to a Virtual Machine (VM), but can result in unexpected consequences related to High Availability in VMware vSphere 6.
- In this video, we'll look at how…vFlash resources are allocated to VMDK's…and examine the impact that has on high availability.…vFlash resources are assigned to virtual machines…at the virtual disk level.…For example, I might have a virtual machine…with two virtual disks.…I can assign vFlash resources to both disks,…or just one disk, or none of that…virtual machine disks.…vFlash does not support shares.…When you assign vFlash to a virtual machine's disk,…you're creating a reservation.…
For example, let's say I create a one gigabyte…vFlash reservation for a virtual disk.…When I power on the virtual machine,…that one gigabyte is reserved for that VM…and cannot be used by any other virtual machines.…A vFlash reservation is sort of like…a thick, provisioned disk.…Before the VM powers on, the host…will do an admission control check…to ensure that the vFlash reservation…can be satisfied.…Once the VM boots up, the vFlash capacity…that is assigned to it is immediately consumed.…
There are no in-guest agents or…special software required for vFlash.…
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