Nexus Repository Memory Overview

The sections below explain the different configurable memory types, Java arguments for managing certain memory configurations, and examples of using those Java arguments.

Configurable Memory Types

The following describes the configurable memory types for Sonatype Nexus Repository deployments; visit the Configuring the Runtime Environment page to learn how to change the default memory settings.

Java Virtual Machine (JVM) Heap Memory

Stores the objects created by the Java application. The JVM manages this space, and a special process called garbage collection automatically cleans up unused objects to free up memory.

You must specify a min (-Xms) and max (-Xmx); these values should be identical
Do not increase the heap memory larger than recommendations or set the min and max to be different; this will cause performance issues
Min allowable is 2703M
If you go beyond 8G, ensure there is enough RAM to handle and that G1GC garbage collection is enabled

Host or OS Physical Memory (RAM)

Total memory that is allocated to the operating system or virtual hardware. Related to the node.

Min allowable is 8G; no max limit
Minimum unallocated host physical memory should be no less than 1/3 of total physical RAM to allow for virtual memory swap
max heap + max direct memory <= host physical/RAM * 2/3

JVM Direct Memory

Reserved section of the operating system's physical memory that Java programs access directly, bypassing and completely independent of heap memory. This is allocated outside of and distinctly from heap memory and is managed by application code that needs to process large amounts of data at once.

Required only for legacy OrientDB
Min allowable is 2703M
Must configure a max value
- (host physical/RAM * 2/3) - JVM max heap

Memory-Related Java Arguments

The table below explains Java arguments that you can use for memory configurations. Examples are provided in the example maximum memory configurations section.

Java Argument	Purpose	Advice
-Xmx	Set Maximum Heap Memory	PostgreSQL / H2 - Set at 50% of host RAM Legacy OrientDB - Set at two-thirds host RAM minus Max Direct Memory
-Xms	Set Minimum Heap Memory	Set identical to Max Heap
-XX:+UseG1GC	(Legacy Java 8 Only) Use G1 Garbage Collection Algorithms	Used for legacy Java 8 only Set if heap is greater than or equal to 8GB
-XX:MaxDirectMemorySize	(Legacy OrientDB Only) Set Java Direct Memory	Do not use for PostgreSQL or H2 In legacy OrientDB deployments, set at two-thirds of host RAM minus Max Heap

Example Maximum Memory Configurations

The table provides examples of memory configuration using the Java arguments.

See the memory-related Java arguments section to learn more.

Physical/RAM Memory	PostgreSQL	H2	OrientDB
8GB	-Xms4G -Xmx4G	-Xms4G -Xmx4G	-Xms2703M -Xmx2703M -XX:MaxDirectMemorySize=2703M
16GB	-Xms8G -Xmx8G	-Xms8G -Xmx8G	-Xms4G -Xmx4G -XX:MaxDirectMemorySize=6717M
32GB	-Xms16G -Xmx16G	Not applicable *	Not applicable *
64GB	-Xms32G -Xmx32G	Not applicable *	Not applicable *

* Deployments of this scale should use PostgreSQL