By default, Linux file systems use a 4K block size. Block size of 4K means all I/O happens 4K at a time. Any *updates* to data smaller than 4K will result in a read-modify-write cycle on disk, ie, if a file was extended from 1K to 2K, the fs will read in the 4K, memcpy the region from 1K-2K into the vm page, then write out 4K again.If you make the block size 1M, the read-modify-write cycle will re