System Requirements

Requirements for Fusion installation are detailed below.

Lucidworks recommends not virus scanning the fusion/data folder. Virus scanning can cause slow performance, and it can cause downtime if it quarantines an index file identified as a possible virus.

Supported Operating Systems

Certain systems may place limits on open files or processes that may be used by a process or user (for example, Unix systems may use ulimit and the limits.conf file). Fusion may require increasing these limits. We recommend setting these to "unlimited" or the maximum allowed by the system. If "unlimited" is not an option, we suggest a minimum limit of 65535 on the number of open files, and a minimum limit of 16384 on the number of processes for the Fusion user.

Supported for production use of Fusion services

Operating system:


  • Oracle JRE or JDK 1.8, 64-bit (x64 only)

  • OpenJDK JRE or JDK 1.8, 64-bit (x64/x86_64 only)

Also supported for trial and development use of Fusion services

Operating system:

  • Windows 7, 8, 8.1, and 10 64-bit (x64 only)

  • Mac OS X 10.8 or later

Hardware requirements

Fusion and Solr nodes

Here are some minimum recommendations for different Fusion deployments. These are for the nodes that run Fusion (including ones that also run Solr and/or ZooKeeper, if those cluster arrangements are used), as well as for external (non-Fusion) nodes for SolrCloud nodes:

Deployment type Memory CPU


16 GB

4 cores

Small Production*

32 GB

8 cores

Large Production**

64+ GB

8+ cores

* Small production environments will have 2+ nodes with these specs, on which both Fusion and Solr are installed. (3+ nodes are recommended.)

** Large production environments will have 3+ nodes with these specs. Additional nodes are needed for an external SolrCloud cluster, if that is used. An external SolrCloud cluster is only necessary for Solr collections with very large numbers of documents (for example, 100 million documents or more), though a Fusion deployment can use it regardless. On these nodes, Fusion and Solr are installed if no external SolrCloud cluster is used. If an external SolrCloud cluster is used, these nodes might or might not have Solr installed.

ZooKeeper nodes

Here are some minimum recommendations for the nodes that run ZooKeeper. These nodes can be more lightweight than the nodes that run Fusion and/or Solr. With the exception of small development/testing deployments, ZooKeeper nodes should only run ZooKeeper (not Fusion or Solr). Because ZooKeeper synchronizes all it’s operations to disk, we recommend using a disk with high throughput and low latency for your ZooKeeper nodes.

Deployment type Memory CPU


4 GB

4 cores

Small Production

4+ GB

4+ cores

Large Production

4+ GB

4+ cores

Fusion components

You can run Fusion components on different nodes. Different Fusion components require different amounts of resources. Below are the minimum recommended memory requirements; consult Lucidworks for specific recommendations tailored to your unique use case, data load, and production needs.

Fusion component Minimum RAM


2 GB

API service

1 GB

Fusion UI

512 MB


2 GB

Spark master

512 MB

Spark worker

1 GB

Java JDK

Fusion is a Java-based application, and thus requires a pre-installed JDK.

Because of the nature of some of the components of Fusion, the Java Runtime Environment is not enough, and the full Java Development Kit must be installed. Components that require the JDK include metrics reporting, and AppStudio based UI components that use JSP under the hood.

Fusion runs on JDK 1.8.

If you are unsure which installation of Java is invoked when Fusion starts, run the following commands from a shell or terminal window:

java -version
javac -version
echo $JAVA_HOME     // Unix
echo %JAVA_HOME%    // Windows

Cluster Requirements

Supported Solr and SolrCloud Versions

Fusion includes an embedded instance of Solr; see the release history to find out which Solr version is included in each Fusion release.

If your search requirements are very large (for example, 100 million documents or more), we recommend that you use an external SolrCloud cluster. (You can use an external SolrCloud cluster regardless.)

Optionally, you can use both embedded Solr instances and an external SolrCloud cluster. In this case, only store logs in the embedded Solr instances. Store data in the external SolrCloud cluster.

Solr 4.4 and higher are supported. Solr 4.6 and 4.7 are not supported, as they contain severe bugs that will impact the ability of Fusion to work with your Solr system.

If you want to know whether other versions of Solr might be compatible with Fusion, you can ask Lucidworks.

If you use an external SolrCloud cluster, it has ZooKeeper bundled with it. However, Apache recommends that you not use the bundled ZooKeeper in production. Instead, create an external ZooKeeper cluster (external to both Fusion and SolrCloud) or use the ZooKeeper embedded with Fusion, depending on the circumstance. For more information, see Supported ZooKeeper Versions and Cluster Requirements.

If you decide to set up an external SolrCloud cluster, check the requirements for this as well in the Solr documentation.

We strongly recommend that you use Network Time Protocol (NTP) on a SolrCloud cluster to ensure that nodes use synchronized time. While this is not strictly required, reasoning about log contents and database entries becomes impossible without it. Information and instructions on how to install and run NTP are available at

Recommended HTTP Clients

The Fusion API can be accessed from any HTTP client, and allows you to build user interfaces and applications that work with any browser. However, the Fusion Administration UI, Dashboards, and built-in Search UI are supported only with:

  • Chrome latest version

  • Firefox latest version and latest ESR

  • Internet Explorer 11