COA Identity, Image, and Compute Management 3 — Questions and Answers
Question 1: A Nova flavor has vcpus=4, ram=8192, disk=20, and an extra spec 'aggregate_instance_extra_specs:ssd=true'. What does the extra spec control?
- It limits the flavor to SSD-backed ephemeral storage only
- It constrains instance placement to host aggregates tagged with ssd=true (Correct answer)
- It enables faster network I/O for the instance
- It sets the swap space to SSD partition
Correct answer: It constrains instance placement to host aggregates tagged with ssd=true
The 'aggregate_instance_extra_specs' prefix causes the Nova scheduler to match the flavor's extra specs against host aggregate metadata, restricting placement.
Question 2: What is the correct Nova command to resize a running instance to a larger flavor while keeping the instance on the same compute host if possible?
- openstack server migrate <instance-id> --flavor <flavor>
- openstack server resize <instance-id> --flavor <flavor> (Correct answer)
- openstack server rebuild <instance-id> --flavor <flavor>
- openstack server rebuild --resize <instance-id> --flavor <flavor>
Correct answer: openstack server resize <instance-id> --flavor <flavor>
'openstack server resize' initiates a resize operation and places the instance in VERIFY_RESIZE state awaiting confirmation after completion.
Question 3: After resizing a Nova instance, the instance is in 'VERIFY_RESIZE' state. What command must the administrator run to finalize the resize?
- openstack server resume <instance-id>
- openstack server confirm resize <instance-id> (Correct answer)
- openstack server reboot <instance-id>
- openstack server start <instance-id>
Correct answer: openstack server confirm resize <instance-id>
'openstack server confirm resize' finalizes the resize, releases the old allocation, and transitions the instance to ACTIVE state.
Question 4: Which Nova mechanism allows an administrator to group compute hosts so that instances can be constrained or spread across physically isolated fault domains?
- Host aggregates
- Availability zones (Correct answer)
- Server groups
- Placement groups
Correct answer: Availability zones
Availability zones are the user-facing abstraction of host aggregates, allowing tenants to select isolated fault domains when launching instances.
Question 5: An operator wants two instances to be guaranteed to run on DIFFERENT physical compute hosts for redundancy. Which Nova server group policy achieves this?
- affinity
- anti-affinity (Correct answer)
- soft-affinity
- soft-anti-affinity
Correct answer: anti-affinity
The 'anti-affinity' policy enforces hard placement of instances on separate compute hosts, failing if no separate host is available.
Question 6: What Nova console type provides a browser-based graphical console using the SPICE protocol, offering better performance than VNC for multimedia workloads?
- novnc
- xvpvnc
- spice-html5 (Correct answer)
- serial
Correct answer: spice-html5
The spice-html5 console type uses the SPICE protocol delivered via HTML5, providing better compression and multimedia support than VNC.
Question 7: A user runs 'openstack server create' with --user-data pointing to a cloud-init script. Where does the running instance retrieve this user data by default?
- From a Glance image property
- From the Nova metadata API at 169.254.169.254 (Correct answer)
- From a Cinder volume attached at boot
- From a Swift object named user-data
Correct answer: From the Nova metadata API at 169.254.169.254
Instances retrieve user data and instance metadata from the Nova metadata API at the link-local address 169.254.169.254, which Nova proxies.
COA Identity, Image, and Compute Management 3
A Nova flavor has vcpus=4, ram=8192, disk=20, and an extra spec 'aggregate_instance_extra_specs:ssd=true'.
What does the extra spec control?