Architecture & System Design Flashcards
7 cards from real COA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Architecture & System Design flashcards as text
What is the function of the oslo.messaging library in OpenStack service communication?
Answer: It abstracts RPC calls and notifications over pluggable message broker backends
oslo.messaging provides a transport-agnostic RPC and notification framework used by most OpenStack services to communicate over message brokers like RabbitMQ.
In Ceph-backed Cinder deployments, what advantage does the RADOS Block Device (RBD) driver provide over traditional shared file storage?
Answer: It enables thin provisioning, copy-on-write snapshots, and direct Nova-to-Ceph access
RBD supports thin provisioning and copy-on-write cloning, and Nova can directly access Ceph avoiding data copying during boot from volume.
Which component in the Neutron architecture is responsible for implementing security group rules on compute nodes?
Answer: OVS/iptables firewall driver on the compute node
Security group rules are enforced by the firewall driver (iptables or OVS-based) running on the compute node, not by central Neutron components.
What is the recommended approach to prevent a 'noisy neighbor' issue where one tenant's workload monopolizes compute resources in OpenStack?
Answer: Using flavor extra specs with CPU pinning and NUMA topology policies
CPU pinning and NUMA topology flavor extra specs ensure dedicated CPU cores are allocated to instances, preventing contention with other tenants' workloads.
In the context of OpenStack Keystone federation, what does Identity Provider (IdP) federation allow?
Answer: Users from an external identity system to authenticate and receive OpenStack tokens
Federation allows users authenticated by an external IdP (e.g., SAML, OIDC) to receive mapped Keystone tokens without needing a local Keystone account.
Which Heat resource type would you use to create a set of identically configured Nova instances that can scale horizontally?
Answer: OS::Heat::AutoScalingGroup
OS::Heat::AutoScalingGroup manages a collection of identical resources and integrates with Ceilometer/Aodh alarms for automatic scaling actions.
When configuring Nova for SR-IOV networking, what must be enabled on the physical host?
Answer: VT-d (IOMMU) in the BIOS and the sriov_numvfs setting on the NIC
SR-IOV requires IOMMU (VT-d on Intel) enabled in BIOS and the number of Virtual Functions configured on the physical NIC via sriov_numvfs.