CSE 221: Homework 3

Winter 2005

Due: Tuesday, March 8, 2005 in class

1. In 1999, Wang et al. proposed a disk drive architecture supporting a service called "eager write". Rather than update a block in place, as with normal disks, an eager writing disk simply writes to the next free block near the disk head (the disk internally keeps track of this mapping by maintaining a table mapping "logical" disk blocks to physical disk blocks). Argue whether using such a disk would improve the performance of a Log-Structured File System, hurt its performance, or make little difference.

2. Many of the papers we have read can be placed into one of two categories: papers that attempt to virtualize a resource to provide transparency to the underlying implementation, and papers that attempt to expose a resource to allow applications to improve their performance. For the following systems, describe which resource is virtualized or exposed and what they hoped to accomplish by doing this:
   1. Scheduler Activations
   2. GMS
   3. IO-Lite
   4. Sprite