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Fusion 5.12
    Fusion 5.12

    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.
    Fusion does not support installation under a directory whose name contains a space.

    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:

    • Windows Server 2012, 2012 R2, and 2016 (x64 only)

      Windows systems must have the Microsoft Visual C++ 2010 SP1 package installed.
    • Linux 64-bit (x86_64/amd64 only) with 2.6 or later kernel

      RedHat based Linux, including CentOS, must be 6.6.x or later. See for more information.


    See Java requirements below.

    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 and later

    For information about the embedded versions of Solr, ZooKeeper, and so forth, see the Release Notes.


    See Java requirements below.

    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.) Even if you have only a small amount of content, we recommend provisioning an 8 core machine as having only 4 cores runs into a possible issue with allocating enough Java heap memory.

    ** Large production environments will have 3+ nodes with these specs.

    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 its 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

    Supported Java Development Kits

    The following JDKs have been tested with Fusion 4.2:

    Java requirements

    Java 8 is recommended for Lucidworks Fusion 4.2. In some cases, Java 9 can be used without issue. Java 10 and later is not supported by Lucidworks Fusion 4.2.

    Fusion is a Java-based application, and some features require a pre-installed JDK. The JRE alone may not be sufficient.

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

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

    • AdoptOpenJDK 1.8, 64-bit (x64 only)

      For Windows users, the Fusion start and stop logging output found in $Fusion\var\logs\metrics\metric.log tends to be more reliable when using AdoptOpenJDK.

    Checking your Java version

    Fusion scripts execute both the java and javac commands, which are usually aliases for the current Java installation. To check which version of Java is invoked, run the following commands from a shell or terminal window:

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

    JavaScript pipeline stages

    Fusion’s JavaScript pipeline stages are application-specific custom JavaScript programs. The first time a pipeline is run, the JDK compiles the JavaScript using the Nashorn JavaScript engine.

    Cluster Requirements

    Supported Solr Versions

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

    Fusion Server 4.2 is certified with Solr 7.5.0 (included).

    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

    Supported ZooKeeper Versions

    Fusion includes an embedded instance of ZooKeeper; see the release history to find out which version of ZooKeeper is included in each Fusion release. For demo, trial, and some testing deployments, you can use the embedded ZooKeeper. For production deployments, we recommend using an external ZooKeeper cluster.

    ZooKeeper 3.4.11 is supported for external ZooKeeper instances.

    A ZooKeeper cluster must have 3+ nodes configured as an ensemble, and it must have an odd number of nodes. We recommend three ZooKeeper nodes in a ZooKeeper cluster/ensemble. Only for very large SolrCloud clusters (50+ nodes) might you need more ZooKeeper nodes.

    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 Extended Support Release (ESR)

    • Internet Explorer 11