Improvement in Performance via Parallelism

• With multiple disks, we can improve the transfer rate as well (or instead) by striping data across the disks.
• In its simplest form, data striping consists of splitting the bits of each byte across multiple disks; such striping is called bit-level striping.
  • For example, if we have an array of eight disks, we write bit $i$ of each byte to disk $i$.
• The array of eight disks can be treated as a single disk with sectors that are eight times the normal size and, more important that have eight times the access rate.
• Parallelism in a disk system, as achieved through striping, has two main goals:
  1. Increase the throughput of multiple small accesses (that is, page accesses) by load balancing.
  2. Reduce the response time of large accesses.