Can some one jusify this formula on image. I mean can you tell us how they get this formula?

External Merge Sort (Cont.) Cost analysis: 1 block per run leads to too many seeks during merge Instead use b, buffer blocks per run > read/write b, blocks at a time Can mergeLM/b1 runs in one pass Total number of merge passes required: 109.Mb0ufbM) | Block transfers for initial run creation as well as in each pass is 2b, for final pass, we don' t count write cost we ignore final write cost for all operations since the output of an operation may be sent to the parent operation without being written to disk Thus total number of block transfers for external sorting: - Seeks: next slide