public static void setupShortCircuitRead(final Configuration conf) {
    // Check that the user has not set the "dfs.client.read.shortcircuit.skip.checksum" property.
    boolean shortCircuitSkipChecksum =
      conf.getBoolean("dfs.client.read.shortcircuit.skip.checksum", false);
    boolean useHBaseChecksum = conf.getBoolean(HConstants.HBASE_CHECKSUM_VERIFICATION, true);
    if (shortCircuitSkipChecksum) {
      LOG.warn("Configuration \"dfs.client.read.shortcircuit.skip.checksum\" should not "
        + "be set to true."
        + (useHBaseChecksum
          ? " HBase checksum doesn't require "
            + "it, see https://issues.apache.org/jira/browse/HBASE-6868."
          : ""));
      assert !shortCircuitSkipChecksum; // this will fail if assertions are on
    }
    checkShortCircuitReadBufferSize(conf);
  }
Do our short circuit read setup. Checks buffer size to use and whether to do checksumming in
hbase or hdfs.
hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSUtils.java