# Before you begin

You must meet the following requirements for using the AEL daemon and operating the Spark engine for transformations:

* Pentaho 9.3 or later installation. See [Pentaho installation](/install/9.3-install/pentaho-installation-overview-cp.md).
* One of the following Hadoop distributions and versions:
  * [Cloudera](https://www.cloudera.com/) 6.1 or later
  * [Hortonworks](https://hortonworks.com/) 3.0 and 3.1
  * [Amazon EMR](https://aws.amazon.com/emr/) 5.21 and 5.24
  * [Microsoft Azure HDInsight](https://docs.microsoft.com/en-us/azure/hdinsight/) 4.0
* Spark client 2.3 or later.
* [Pentaho Spark application](/install/9.3-install/pentaho-configuration/tasks-to-be-performed-by-an-it-administrator/set-up-the-adaptive-execution-layer-ael/before-you-begin/pentaho-spark-application.md) 9.3.
* If you are configuring AEL for use with Cloudera, Hortonworks, or Amazon EMR, review [Vendor-Supplied Clients](/install/9.3-install/pentaho-configuration/tasks-to-be-performed-by-an-it-administrator/set-up-the-adaptive-execution-layer-ael/vendor-supplied-clients.md).

**CAUTION:**

Spark does not support having Hadoop 2.x JAR files and Hadoop 3.x JAR files on the same class path as your spark application. Do not mix and match Hadoop versions.

**Note:** The dependency on Zookeeper was removed in Pentaho 8.0. If you installed AEL for Pentaho 7.1, you must delete the `adaptive-execution` folder and follow the Pentaho 8.0 or later Installation instructions to use AEL with Pentaho 8.0 or later.


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