Mega Flowcache hit rate low alarm

Products

• VMware NSX

Issue/Introduction

Title: Alarm for Mega flowcache hitrate
Event ID: edge_health.mega_flow_cache_hit_rate_low
Alarm Description

• Purpose: Indicates degradation in Edge performance
• Impact: Decreased Edge performance

Environment

VMware NSX-T Data Center

Edge Form factors:

• Bare Metal Edge
• VM Edge

Cause

Reason for low Flow Cache hit rate:

• Unsupported traffic type
• Short lived traffic
• Number of traffic flows / streams is greater than the size of Flow cache. 

Resolution

Steps to Resolve
For 3.2.0 and higher

Recommenced Action:

• The Mega flow cache stats can be obtained using 'get dataplane flow-cache stats' Edge node CLI.
  
  Snippet of sample output for get dataplane flow-cache stats with Mega flow cache stats
  
  
  
  
• If the alarm persists for a long period of time or happens often move to an Edge with larger form factor.
  To increase form factor follow the steps to Redeploy NSX Edge. In case of VMC follow the steps to Scaleup SDDC.
  Note: This resolution does not apply for a Bare metal edge.

Maintenance window required for remediation? Yes

Additional Information