Virtual machines

The available types of virtual machines in a tenant are based on different performance parameters:

• Resource sizing

• Standard or dedicated processing (vCPU)

• Standard or dedicated memory (RAM)

• Standard or accelerated (VNF optimized) network performance

In the DT Cloud Services cloud, virtual hardware templates are used to configure VM types based on a set of parameters. These are known as virtual machine flavors. Creation and management of VMs over the OpenStack API is described in https://pannet.atlassian.net/l/c/x97XNmPe

In general, there is a difference between publicly available flavors and custom flavors. Public flavors are readily available for instant use. Custom flavors need to be configured by DT Cloud Services and are made available as a “template”.

Contents

Resource parameters

Resource sizing refers to the number of virtual resources required for a virtual machine, as denoted by the number of vCPUs, GB of RAM and GB of Storage.

Standard processing offers vCPUs from compute nodes that rely on a certain level of oversubscription of processing power. In practice, the processing power of that compute node is then shared between different applications.

Dedicated processing offers vCPUs that are pinned to your virtual machine for exclusive utilization. Specific CPU arrangements for particular NUMA architectures are also supported.

Standard memory offers RAM that is not generally oversubscribed and that is performance optimized for workloads that are highly memory IO-bound (based on the OpenStack feature “Huge Pages”). For standard memory, a minor oversubscription may occur at certain points in time.

Dedicated memory offers RAM that is not oversubscribed and that is performance optimized for workloads that are highly memory IO-bound (based on the OpenStack feature “Huge Pages”).

The configuration options for shared hosts are shown in Figure 1. The flavors represent configuration of hosts with standard processing, in Boron referred to by the flavor labels standard or performance.

Figure 1. Configuration options for shared host.

For technical details of shared hosts with dedicated processing, see https://pannet.atlassian.net/l/c/9SjHyPvS

Predefined flavors in Beryllium

Readily available public flavors with standard processing and memory and standard network performance are offered in the sizes listed in Table 1.

_{Table 1. Predefined public flavors in Beryllium.}

Predefined flavors in Boron

A large number of predefined public flavors are available in Boron, classified into standard and performance types of configurations as listed in Table 2, where standard flavors are using vCPU resources in shared mode and performance are using dedicated vCPUs with CPU-pinning, giving the VM exclusive access to the resource.

_{Table 2. Predefined public flavors in Boron.}

Infographic: Virtual Machine Flavors in Boron

Custom flavors

In the DT Cloud Services cloud, customized flavors can be specified by the user in case the public flavors are unsuitable. Custom flavors are configured by the DT Cloud Services operations team and made available to the user. Such flavors offer a wide degree of flexibility and options based on the following parameters:

• Resource sizing

• Standard or dedicated mode of processing (vCPU)

• Standard or dedicated memory (RAM)

• Standard or accelerated (VNF optimized) network performance

Please note that custom flavors are intended for situations where none of the predefined flavors can be used - typically instances with very high capacity.