ASSIGNMENT 8, November 4 through November 11, 2011

For Class Discussion Monday Nov 7, 2011

We continue discussing atomicity and recoverability. In preparation read Chapter 9 (Atomicity) Sections 1, 2 and 3. This material should be familiar to you from cs31a but here S&K book provides a more general systems perspective.

The technical reading for the discussion is: "The design and implementation of a log-structured file system", by Mendel Rosenblum and John K. Ousterhout.

For your reading report answer the following question:

What the major differences are between LFS and a standard UNIX file system. What hardware advances does LFS take advantage of? Which components of the UNIX file system does LFS re-use and why?

For Class Discussion, Wednesday, November 9, 2011

We continue with the study of transactions. Please review Chapter 9 sections 1-3. Your reading assignment is the classical system R recovery manager paper by Jim Gray, the "father" of transaction systems and his team. This is a long and difficult paper. The introduction summarizes the whole of System R, which provides a number of features beyond the recovery features focused on in this paper. You should read this section, but do not worry if there are details you do not understand. Sections 1 and 2 are the meat of the paper, and you should try to understand them as much as possible. Because this paper is quite dense, you may wish to skim these sections first, trying to understand the basic approach to recovery. Section 3 is a retrospective on the recovery features of System R; you do not need to focus on the details of this section, but you should read it quickly as it provides an interesting discussion of things that were problematic in the design presented in the previous two sections.If there are terms or concepts you did not understand while reading the paper, be sure to ask about them in class! Here is your system R reading question:
Do shadow files and logging solve the same problem in System R, or different problems? Why are both mechanisms there?

System aphorism of the week
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair.       - Douglas Adams, Mostly Harmless (Hitch Hiker's Guide to the Galaxy V, Heinemann,       London, 1992. ISBN 0434 00926 1)

CS 146a Handout 8, updated 11/3/11