Configuring Short-Circuit Reads

So-called "short-circuit" reads bypass the DataNode, allowing a client to read the file directly, as long as the client is co-located with the data. Short-circuit reads provide a substantial performance boost to many applications and help improve HBase random read profile and Impala performance.

Short-circuit reads require (the Hadoop Native Library) to be accessible to both the server and the client. You must install from an .rpm, .deb, or parcel to use short-circuit local reads.

Configuring Short-Circuit Reads Using Cloudera Manager

Minimum Required Role: Configurator (also provided by Cluster Administrator, Full Administrator)

  1. Go to the HDFS service.
  2. Click the Configuration tab.
  3. Select Scope > Gateway or HDFS (Service-Wide).
  4. Select Category > Performance.
  5. Locate the Enable HDFS Short Circuit Read property or search for it by typing its name in the Search box. Check the box to enable it.

    To apply this configuration property to other role groups as needed, edit the value for the appropriate role group. See Modifying Configuration Properties Using Cloudera Manager.

  6. Enter a Reason for change, and then click Save Changes to commit the changes.