Preparation for Recitation 18

The primary assignment for this week is to continue to read ARIES: A Transaction Recovery Method Supporting Fine Granularity Locking and Partial Rollbacks Using Write-Ahead Logging (reading #14 in the course packet). Read sections 4, 5, and 6 - 6.3.

You may wish to refer to last week's reading assignment for some basic definitions and vocabulary related to ARIES.

As you read the assigned sections of the paper, try answer the following questions (the first two were assigned last week as well, but you may wish to see if you can answer them more satisfactorily in light of the new sections of the paper you have read):

• What do the author's mean when they say ARIES "repeats history"? In what ways does repeating history simplify the design of ARIES?

• What is the purpose of the CLR records that ARIES writes? What could go wrong if ARIES didn't write CLR records?

• In what ways does the ARIES protocol differ from the protocol described in Section 9.C of the course notes? Why do the approaches differ in the ways that they do?

Also read Chocolate (reading #16 in the course packet) to learn an interesting take on fail-soft design of complex systems. Compare the recommendations of this short paper with the instructions in the U. S. Navy Flight Manual:

If you are lost,

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