Current the minimum block size is defined by "dfs.namenode.fs-limits.min-block-size" with default value 1MB. Default block size is defined by "dfs.blocksize" with default value 128MB. Maximum erasure coding policy cell size is defined by "dfs.namenode.ec.policies.max.cellsize" with default value 4MB. We need to make sure the erasure coding policy cell size should not be greater than file block size. Otherwise file read/write will fail.