# Estimating Heap Sizes

## General Memory Guidelines

- Minimum physical/RAM memory on the host 16GB for production use
- Minimum heap ( -Xms ) must equal set maximum heap ( -Xmx )
- Minimum heap size 8GB for production use
- Minimum unallocated host physical/RAM memory should be no less than 1/3 of total physical RAM to allow space for OS, application binaries, and SCM integration

**Note**  
When sizing IQ Server memory, leave space for off-heap direct memory and OS file cache. For larger deployments, set `-XX:MaxDirectMemorySize` explicitly and use `-Djdk.nio.maxCachedBufferSize=262144`.
- For heap >= 8GB recommend using G1GC garbage collector

## Guidelines for Heap Sizing

These profiles help gauge the typical physical memory requirements needed for a dedicated server host running IQ Server. _Due to the inherent complexities of use cases, one size does not fit all and this should only be interpreted as a guideline._

| Profile Use Case | Physical/RAM Memory | Heap Settings |
| --- | --- | --- |
| Personal<br>(no. of applications< 20) | 8GB | -Xmx4g -Xms4g |
| Small team<br>(no. of applications <100) | 16GB | -Xmx8g -Xms8g -XX:+UseG1GC |
| Medium team<br>(100 <applications <1000) | 24GB | -Xmx16g -Xms16g -XX:+UseG1GC |
| Large, enterprise<br>(no. of applications > 1000) | 32GB+ | -Xms16g -Xmx16g -XX:MaxDirectMemorySize=8g -Djdk.nio.maxCachedBufferSize=262144 -XX:+UseG1GC |

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