5.5

For example, assume you have 2GHz available and specify a reservation of 1GHz for VM1 and 1GHz for
VM2. Now each virtual machine is guaranteed to get 1GHz if it needs it. However, if VM1 is using only
500MHz, VM2 can use 1.5GHz.
Reservation defaults to 0. You can specify a reservation if you need to guarantee that the minimum required
amounts of CPU or memory are always available for the virtual machine.
Resource Allocation Limit
Limit specifies an upper bound for CPU and memory resources that can be allocated to a virtual machine.
A virtual datacenter can allocate more than the reservation to a virtual machine, but never allocates more
than the limit, even if there are unused resources on the system. The limit is expressed in concrete units
(megahertz or megabytes).
CPU and memory resource limits default to unlimited. When the memory limit is unlimited, the amount of
memory configured for the virtual machine when it was created becomes its effective limit in most cases.
In most cases, it is not necessary to specify a limit. You might waste idle resources if you specify a limit. The
system does not allow a virtual machine to use more resources than the limit, even when the system is
underutilized and idle resources are available. Specify a limit only if you have good reasons for doing so.
Configure Virtual Machine Resource Allocation Settings
You can configure the resource allocation settings (shares, reservation, and limit) to determine the amount
of CPU, memory, and storage resources provided for a virtual machine.
For more information about shares, reservations, and limits, see “Resource Allocation Shares,” on page 100,
“Resource Allocation Reservation,” on page 100, and “Resource Allocation Limit,” on page 101.
Prerequisites
A reservation pool virtual datacenter.
Procedure
1 Click My Cloud.
2 In the left pane, click VMs.
3 Select a virtual machine, right-click, and select Properties.
4 Click the Resource Allocation tab and set the priority, reservation, and limit for CPU and memory.
5 Click OK.
Modifying Virtual Machine Hard Disks
You can add hard disks, edit hard disks, and delete hard disk from a virtual machine.
You do not have to power off virtual machines that are not fast provisioned to add or edit a virtual machine
hard disk.
Add a Virtual Machine Hard Disk
You can add a virtual hard disk to a virtual machine.
Prerequisites
If the virtual machine uses fast provisioning, power off the virtual machine. Non-fast-provisioned virtual
machines support adding virtual machine hard disks while the virtual machine is running.
Chapter 8 Working with Virtual Machines
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