Schedule
Paper & Questions
Lec.2 Question
Paper: Shared Virtual Memory
ivy-code.txt is a version of the code in Section 3.1 with
some clarifications and bug fixes. The write fault handler ends by sending a confirmation to the manager,
and the "Write server" code in the manager waits for this confirmation. Suppose you eliminated this
confirmation (both the send and the wait) from the system. Describe a scenario in which lack of the
confirmation would cause the system to behave incorrectly. You should assume that the network delivers all
messages, and that none of the computers fail.
Lec.3 Question
Paper: Don't Settle for Eventual: Scalable Causal
Consistency for Wide-Area Storage with COPS
Suppose an application client at data center D1 writes object x with version 2 (x_2) and then object y
with version 3 (y_3). Suppose y_3 has propagated from data center D1 to data center D2 but x_2 has not yet
arrived at D2. Suppose another application client data center D2 has just read Y_3, is it possible that it
might read x_1 next? (If not, why not?) Will the client be blocked waiting for x_2 to arrive from D1? (If
not, why not?)
Lec.4 Question (no need to bring it to the class :) )
Paper: Reimplementing the Cedar File System Using
Logging and Group Commit
At the end of Section 4, the paper says that during a one-byte file create FSD writes the leader+data page
synchronously to the disk, but records the update to the file name table in memory and only writes it back
to disk later. Why do you suppose the FSD designers decided to write the data page synchronously? What (if
anything) might go wrong if FSD instead wrote the file's data in the in-memory disk cache, and only wrote
it to disk later?
Lec.5 Question
Paper & Question: A Critique of ANSI SQL Isolation
Levels
Snapshot isolation (SI) differs from serilizatiability due to one anomaly that is possible under SI but
not under serilizatiability. Describe the anomality and also give a concrete application for which the
anomaly is undesirable.
Lec.6 Question
Paper: Sinfonia: A
New Paradigm for Building Scalable Distributed Systems
What's the difference between coordinator in mini-transaction's 2PC protocol and standard 2PC protocol?
Credits: questions and papers from MIT 6.824 and part of slides come from Paul Krzyzanowski (Rutgers), Haibo Chen (SJTU) and et al.