Section 7 – Establish Service Levels
- Objective 7.3 – Create and Configure Resource Pools
A resource pool exists with a memory reservation of 14GB. The pool has 5 single-processor virtual machines and 2 dual-processor virtual machines. Each of these VMs has a memory reservation of 2GB. When an attempt is made to power on the seventh Virtual Machine in the resource pool, a single-processor VM with a 2GB memory reservation, a warning states there is insufficient memory resources to power on
the VM. The reason for this warning is?
A.The VMkernel device drivers are consuming memory
B.Service Console memory has not been increased to accommodate the virtual machine workload
C.Overhead memory for the VMs is consuming memory in the resource pool
D.Memory reservations for the VMs are consuming memory in the pool
vSphere Resource Management Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 28
Virtual machines incur overhead memory. You should be aware of the amount of this overhead.
Table 3-2 lists the overhead memory (in MB) for each number of VCPUs.
Table 3-2. Overhead Memory on Virtual Machines
(MB) 1 VCPU 2 VCPUs
2048 137.81 198.20
There are currently 6 virtual machines powered up, consuming
6 x 2GB reservations = 12GB
4 single processor machines, = 4 x 137.81 MB = 552MB
2 dual processor machines, = 2 x 198.20 MB = 396 MB
Total memory consumed is 12.92 GB, so total memory available = 1.08GB
When an attempt is made to power on the seventh Virtual Machine in the resource pool, an additional 2 GB + 137 MB is required. Since this is not available, the machine cannot start.
Which of the following are benefits of using resource pools (Choose three)?
A.access control and delegation
B.isolation within pools, sharing between pools
C.separation of resources from hardware
D.automatically apply reservations and limits to groups of virtual machines
Why Use Resource Pools?
Resource pools allow you to delegate control over resources of a host (or cluster), but the benefits are especially evident when you use resource pools to compartmentalize all resources in a cluster. You can create multiple resource pools as direct children of the host or cluster and configure them, then delegate control over them to other individuals or organizations. Using resource pools can result in the following benefits:
Flexible hierarchical organization – You can add, remove, or reorganize resource pools or change resource allocations as needed. Isolation between pools, sharing within pools – Top-level administrators can make a pool of resources available to a department-level administrator. Allocation changes that are internal to one departmental resource pool do not unfairly affect other unrelated resource pools.
Access control and delegation – When a top-level administrator makes a resource pool available to a department-level administrator, that administrator can then perform all virtual machine creation and management within the boundaries of the resources to which the resource pool is entitled by the current shares, reservation, and limit settings.
Delegation is usually done in conjunction with permissions settings, which are discussed in the Introduction to Virtual Infrastructure.
Separation of resources from hardware – If you are using clusters enabled for DRS, the resources of all hosts are always assigned to the cluster. That means administrators can perform resource management independently of the actual hosts that contribute the resources. If you replace three 2GB hosts with two 3GB hosts, you don’t need to make changes to your resource allocations.
This separation allows administrators to think more about aggregate computing capacity and less about individual hosts.
Management of sets of virtual machines running a multi-tier service – You don’t need to set resources on each virtual machine. Instead, you can control the aggregate allocation of resources to the set of virtual machines by changing settings on their enclosing resource pool.
Which of the following is true regarding a mixed DRS cluster with Intel and AMD based ESX Hosts (Choose Two)?
A.VMware HA will failover virtual machines to any host in the cluster
B.VMware DRS can load balance running virtual machines using all hosts in the cluster
C.VMotion can move live virtual machines between any two hosts in the cluster
D.Storage VMotion will function with any host in the cluster
DRS Performance and Best Practices VMware® Infrastructure 3
If you are configuring a DRS cluster with heterogeneous hosts, be sure to consider the following factors:
VMotion hardware compatibility-Virtual machines cannot use VMotion to migrate across different CPU types (from Intel to AMD or vice versa
VMware DRS and VMotion: Improve workload balance, prevent problems Simply put, DRS ensures that your resource requirements are enforced. You start with a number of VMware host systems, shared storage, same network presence, and resource pools that you define. From there, DRS will balance the workload across the resources you presented to the cluster.
Which of the following are valid permissions for a Resource Pool Administrator (Choose Two)?
A.Assign a vApp to a Resource Pool
B.Move a Resource Pool
D.Add a Host to a Cluster
An Administrator notices that when a virtual machine is placed into a resource pool, a warning indicates that the virtual machine would receive a very large percentage of the total shares for memory. Which of the following actions could be taken to resolve this problem?
A.Increase the memory resource allocation to the resource pool
B.Change the Shares setting from High to Medium or Low for the virtual machine
C.Change the Shares setting from custom to High, Medium or Low for the virtual machine
D.Increase the Share value for the resource pool
vSphere Basic System Administration vCenter Server 4.0 ESX 4.0 ESXi 4.0, page 157
The Memory Resources panel lets you allocate memory resources for a virtual machine and specify
reservations, limits, and shares. Symbolic values Low, Normal, High, and Custom are compared to the sum of all shares of all virtual machines on the server and, on an ESX host, the service console.
By decreasing the memory share of a particular system, it receives less memory out of the total available memory.
An administrator has 2 ESX Hosts, both with a Production and a Test Resource Pool.
Which of the following is true when these hosts are added to a cluster that is not enabled for DRS?
A.The resource pools are combined into a single Production and a single Test pool for the cluster
B.The resource pools are removed
C.The resource pools are grafted into the cluster, resulting in 2 sets of separate Production and Test pools
D.An option is given during the process to graft or combine the pools
The resource pools are removed, as below.
Which of the following resources can be managed using resource pools?
vSphere Resource Management Guide, ESX 4.0, ESXi 4.0, vCenter Server 4.0, page 35.
A resource pool is a logical abstraction for flexible management of resources. Resource pools can be grouped into hierarchies and used to hierarchically partition available CPU and memory resources.