OpenStack Instances

An instance is the OpenStack term for a virtual machine. An instance is just like any other virtual machine in that it is functionally identical to a physical server but can be created and destroyed in moments and its characteristics, such as disk space, RAM and vCPUs can be modified as needed.

An instance is composed of the following resources:

• An OS and storage space (from either an image, volume or snapshot)
• RAM
• Virtual CPU (at least one)

It must also:

• Be attached to a network
• Have a security group applied

An instance is allocated these resources once it is created and will continue to occupy them even if the instance is not running. By ensuring an instance always reserves the resources it has been allocated, it is always able to boot. The only way to free up these resources is to terminate i.e. destroy, the instance.

When you first log into your Memset OpenStack dashboard you will not find any instances created or running. However, you will find some images of standard Linux distributions included.

These images can be found under the Public tab on the images page and will be offered as Boot Sources on the Launch Instance dialogue. You are not limited to only using these images and are free to build and deploy your own instances.

The instance dashboard overview looks like the following:

The dashboard overview provides both information on all created instances and also all of the options to manage the instances via the Actions drop-down menu on the right. These actions include:

• Starting
• Stopping
• Pausing
• Resizing (RAM, disk and CPU)
• Terminating