NCP Nutanix Architecture and Concepts 4 — Questions and Answers
Question 1: What is Nutanix Erasure Coding (EC-X) and when is it most beneficial?
- A RAID-like technique that reduces storage overhead for cold data by encoding it across nodes instead of full replicas (Correct answer)
- A compression algorithm that runs during write I/O
- A method of encrypting data at rest using AES-256
- A snapshot technology for instant VM recovery
Correct answer: A RAID-like technique that reduces storage overhead for cold data by encoding it across nodes instead of full replicas
EC-X uses a RAID-like stripe across nodes to provide data redundancy with less storage overhead than full RF2/RF3 replication, ideal for cold or infrequently accessed data.
Question 2: In Prism Central, what does the 'X-Play' feature provide?
- A gaming interface for training purposes
- Automated playbooks that trigger actions based on events or alerts (Correct answer)
- A cross-cluster replication scheduler
- A load testing tool for HCI performance
Correct answer: Automated playbooks that trigger actions based on events or alerts
X-Play is Nutanix's automation engine in Prism Central that lets administrators create playbooks to automatically respond to alerts and events with predefined actions.
Question 3: How does Nutanix achieve storage locality for VM I/O?
- By placing all VM data on a single centralized NFS filer
- By pinning VMs to specific hosts so their data is always stored on the local node's drives
- By preferentially storing a VM's data on the same node where the VM is running to minimize network traffic (Correct answer)
- By using RDMA to reduce latency for remote storage access
Correct answer: By preferentially storing a VM's data on the same node where the VM is running to minimize network traffic
Nutanix's data locality principle ensures that data written by a VM is preferentially stored on the same node's disks, reducing cross-network I/O for read operations.
Question 4: What happens to data locality when a VM is vMotioned (live migrated) to another node in Nutanix?
- All VM data is immediately migrated to the new node's local storage
- Data remains on the original node; Nutanix migrates it opportunistically in the background based on access patterns (Correct answer)
- The VM loses access to storage until data migration completes
- Prism Central blocks vMotion to preserve data locality
Correct answer: Data remains on the original node; Nutanix migrates it opportunistically in the background based on access patterns
After a live migration, the VM reads data remotely from the original node, and Nutanix opportunistically migrates the data to the new node in the background to restore locality.
Question 5: Which Nutanix storage feature allows multiple VMs to share a single vDisk efficiently by storing only unique blocks?
- Linked Clones via thin-provisioned snapshots (Correct answer)
- NFS multi-attach shares
- Distributed Object Storage
- iSCSI multipathing
Correct answer: Linked Clones via thin-provisioned snapshots
Nutanix uses a redirect-on-write snapshot mechanism to create space-efficient linked clones where VMs share a base vDisk and only unique changed blocks are stored per VM.
Question 6: What is the Nutanix 'Medusa' service responsible for?
- Running Cassandra queries on behalf of other services acting as an abstraction layer (Correct answer)
- Managing network flows between VMs
- Performing disk I/O scheduling for SSDs
- Handling authentication tokens for API calls
Correct answer: Running Cassandra queries on behalf of other services acting as an abstraction layer
Medusa is a metadata abstraction layer that provides a unified API for other Nutanix services to access Cassandra metadata without directly managing distributed database connections.
Question 7: In Nutanix AHV networking, what is a 'Virtual Switch' and how does it differ from a traditional vSwitch?
- It is identical to a VMware Standard Switch
- It is an Open vSwitch-based distributed virtual switch that spans all AHV nodes and is managed centrally through Prism (Correct answer)
- It requires a dedicated physical NIC per VM for isolation
- It is a hardware-offload switch embedded in the NIC firmware
Correct answer: It is an Open vSwitch-based distributed virtual switch that spans all AHV nodes and is managed centrally through Prism
AHV uses Open vSwitch (OVS) as a distributed virtual switch managed centrally through Prism, providing consistent network policy across all nodes without per-host configuration.
NCP Nutanix Architecture and Concepts 4
What is Nutanix Erasure Coding (EC-X) and when is it most beneficial?