public static Reader createReader(FileSystem fs, Path path, Configuration conf)
    throws IOException {
    // The primaryReplicaReader is mainly used for constructing block cache key, so if we do not use
    // block cache then it is OK to set it as any value. We use true here.
    return createReader(fs, path, CacheConfig.DISABLED, true, conf);
  }
Creates reader with cache configuration disabled
@param fs   filesystem
@param path Path to file to read
@param conf Configuration
@return an active Reader instance
@throws IOException Will throw a CorruptHFileException (DoNotRetryIOException subtype) if hfile
                    is corrupt/invalid.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java