The Bottom Line - Mastering VMware vSphere 5.5 - page 773

Control network and storage I/O utilization. Memory, CPU, network I/O, and storage I/O
make up the four major resource types that VMware vSphere administrators must effectively
manage in order to have an efi cient virtualized datacenter. By applying controls to network
I/O and storage I/O, administrators can help ensure consistent performance, meet service-
level objectives, and prevent one workload from unnecessarily consuming resources at the
expense of other workloads.
Master It Name two limitations of Network I/O Control.
Solution Network I/O Control works only with vSphere Distributed Switches and it
requires vCenter Server in order to operate. Another limitation is that system network
resource pools cannot be assigned to user-created port groups.
Master It What are the requirements for using Storage I/O Control?
Solution All datastores and ESXi hosts that will participate in Storage I/O Control must
be managed by the same vCenter Server instance. In addition, raw device mappings
(RDMs) are not supported. Datastores must have only a single extent; datastores with
multiple extents are not supported.
Utilize Flash Storage Flash storage is more popular than ever, and vSphere 5.5 has intro-
duced the new vFlash Cache feature to sit alongside the Swap to Host Cache feature. This
new resource type benei ts environments that need maximum performance.
Master It You have a VM that has a large I/O requirement. Which l ash feature should
you coni gure and why?
Solution vFlash Cache should be used. This feature acts like a buffer to help accelerate
IO for coni gured disks within individual VMs. The other feature, Swap to Host Cache, is
for environments that are memory overcommitted.
Chapter 12: Balancing Resource Utilization
Coni gure and execute vMotion. vMotion is a feature that allows running VMs to be
migrated from one physical ESXi host to another physical ESXi host with no downtime to end
users. To execute vMotion, you must make sure both the ESXi hosts and the VMs meet spe-
cii c coni guration requirements. In addition, vCenter Server performs validation checks to
ensure that vMotion compatibility rules are observed.
Master It A certain vendor has just released a series of patches for some of the guest
OSes in your virtualized infrastructure. You request an outage window from your super-
visor, but your supervisor says to just use vMotion to prevent downtime. Is your supervi-
sor correct? Why or why not?
Solution Your supervisor is incorrect. vMotion can be used to move running VMs from
one physical host to another, but it does not address outages within a guest OS because
of reboots or other malfunctions. If you had been requesting an outage window to apply
updates to the host, the supervisor would have been correct—you could use vMotion to
move all the VMs to other hosts within the environment and then patch the i rst host.
There would be no end-user downtime in that situation.
Master It Is vMotion a solution to prevent unplanned downtime?