Network_Appliance
NS0-157 · Question #392
NS0-157 Question #392: Real Exam Question with Answer & Explanation
The correct answer is A: Place all volumes for the application on the nodes with Flash Pools.. For OLTP workloads with extreme small random writes, Flash Pool nodes are the correct choice because Flash Pool SSDs provide a write cache tier, while FlashCache is primarily a read cache.
Question
A customer has a 4-node cluster. Two nodes have FlashCache and the other two nodes have Flash Pools. The customer is interested in deploying and OLTP application with a workload that consists of an extreme number of small random writes on four LUNs spread across four volumes. What should the customer do to improve performance for the OLTP application?
Options
- APlace all volumes for the application on the nodes with Flash Pools.
- BDeploy all volumes for the application on the two nodes with the FlashCache installed.
- CSplit the volumes between the two nodes with FlashCache and two of the nodes with Flash Pools.
- DPlace the volume with the highest read load on the Flash Pool nodes and place the other volumes
Explanation
For OLTP workloads with extreme small random writes, Flash Pool nodes are the correct choice because Flash Pool SSDs provide a write cache tier, while FlashCache is primarily a read cache.
Common mistakes.
- B. FlashCache (Performance Acceleration Module) is a read cache that caches frequently accessed blocks in flash memory on the controller - it does not provide a write caching tier, so it offers no benefit for write-intensive OLTP workloads.
- C. Splitting volumes between FlashCache and Flash Pool nodes gives only half the volumes the benefit of SSD write caching, unnecessarily leaving the FlashCache-hosted volumes without write acceleration.
- D. Routing only the highest read-load volume to Flash Pool nodes ignores the stated workload characteristic of extreme random writes across all four volumes, leaving most of the write workload without SSD-backed write caching.
Concept tested. Flash Pool write caching vs FlashCache read caching for OLTP
Reference. https://docs.netapp.com/us-en/ontap/concepts/flash-pool-aggregates-concept.html
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