public static boolean supportSafeMode(FileSystem fs) {
    // return true if HDFS.
    if (fs instanceof DistributedFileSystem) {
      return true;
    }
    // return true if the file system implements SafeMode interface.
    if (safeModeClazz != null) {
      return (safeModeClazz.isAssignableFrom(fs.getClass()));
    }
    // return false if the file system is not HDFS and does not implement SafeMode interface.
    return false;
  }
If DFS, check safe mode and if so, wait until we clear it.
@param conf configuration
@param wait Sleep between retries
@throws IOException e
hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSUtils.java