Core Components Flashcards

What is the role of the 'neutron-l3-agent' in an OpenStack deployment?

Answer: Provides Layer 3 routing and floating IP NAT between networks

The neutron-l3-agent manages virtual routers on network nodes, performing routing between tenant subnets and NAT for floating IPs.

In OpenStack, what does 'live migration' allow an operator to do?

Answer: Transfer a running VM from one compute host to another with minimal interruption

Live migration moves a running instance between compute hosts while it continues to serve traffic, useful for host maintenance.

Which storage protocol is most commonly used when attaching a Cinder volume to a Nova instance in production?

Answer: iSCSI

iSCSI is the most widely used protocol for attaching Cinder block volumes to Nova instances, transporting SCSI commands over TCP/IP.

What is the purpose of a Glance 'image property' (metadata)?

Answer: Storing key-value pairs that describe the image and influence scheduler behavior

Glance image properties are arbitrary key-value metadata attached to images that can influence Nova scheduling, driver behavior, and filtering.

Which OpenStack service provides auto-scaling and orchestration of application stacks?

Answer: Heat

Heat provides stack orchestration and supports auto-scaling policies via integration with Ceilometer/Aodh to grow or shrink resource groups.

In Keystone's RBAC model, what is a 'role assignment'?

Answer: Granting a role to a user or group on a specific project or domain

A role assignment links a Keystone role (e.g., 'admin', 'member') to a user or group scoped to a project or domain, determining what actions they can perform.

What is the function of the OpenStack 'placement' service (originally part of Nova)?

Answer: Tracking resource provider inventories and allocations for scheduling decisions

The Placement API tracks resource providers (compute nodes, shared storage) and their allocations, enabling the Nova scheduler to make accurate placement decisions.