This is a known behavior in VMware NSX for vSphere 6.2.x where heap memory is limited to 1.5GB.
Notes:
- In VMware NSX for vSphere 6.2.4 and later, the heap memory has been increased from 1.5GB to 3GB for Servers with 128GB or more memory. This improves consolidation ratio.
- The increase from 1.5GB to 3GB in NSX for vSphere 6.2.4 is only applicable for vSphere 6.0 and later. If you run NSX for vSphere 6.2.4 on vSphere 5.5, the 1.5GB limit still applies.
- In VMware NSX for vSphere 6.3.0, Global Address Sets is introduced which significantly reduces heap memory. Global Address Sets are disabled by default.
To avoid this issue, VMware recommends you to use one of these options:
- Ensure that free heap memory is always greater than 20%.
- Configure Distributed Resource Scheduling (DRS) to Manual mode and migrate virtual machines manually to maintain the right consolidation ratio.
Note: For more information on design recommendations, see the Professional Services.