private long[] createRandomFileDispersed(Path file, int numBlocks,
DatanodeDescriptor primaryNode, DatanodeDescriptor altNode)
throws IOException, InterruptedException {
BlockPlacementPolicyFakeData bp = BlockPlacementPolicyFakeData.lastInstance;
DatanodeDescriptor tmp = bp.overridingDatanode;
final int repl = 1;
long[] crcs = new long[numBlocks];
CRC32 crc = new CRC32();
Random rand = new Random();