---

Cost simplication in parallel data processing

---

• Simplication in cost of parallel data processing
  • Fact:

    Disk access is more costly than transfering data in a local area network (Ethernet)

    ---

    ---

  • Example:

    Time to access 1 data block (~ 4 KBytes) from disk: approximately: 10 msec Time to transfer 4 KBytes of data with 1 Gbit Ethernet: 4 KBytes = 4000 × 8 = 32,000 bits 32,000 Time to transmit 32,000 bits = -------------- × 1000 msec 1,000,000,000 = 0.032 msec

    ---

    ---

  • Therefore:

    We ignore the data transfer time in the performance analysis of Relational Algebra operations (and only consider the # disk block read/write)