  The increasing imbalance between the computing capabilities of individual
nodes and the internode bandwidth makes it highly desirable for any Lattice QCD
algorithm to minimize the amount of internode communication. One of the
relatively new methods for this is the `Split Grid' or `Split Domain' method,
where data is rearranged within the running of a single binary, so that the
routines which requires significant off-node communications such as Dirac
operators are run on multiple smaller partitions in parallel with a better
surface to volume ratio, while other routines are run in one partition.
  While it is relatively straightforward to utilize Split Grid method for
inverters, the typical Lanczos algorithm which has one starting vector does not
render itself naturally to Split Grid method. In this report we investigate the
Block Lanczos algorithm(BL), which allows multiple starting vectors to be
processed in parallel. It is shown that for a moderate number of starting
vectors, BL achieves convergence comparable to similarly tuned Implicitly
Restarted Lanczos algorithm (IRL) on 2+1-flavor physical DWF/M\"obius ensemble.
