Must know of
advantages and disadvantages
- What is the role of middleware in a distributed system?
- A distributed system is blablabla first, and
then answer the question.
Chapter 1: goals
- Explain what is meant by distribution transparency, and give
examples of different types of transparency.
- Distribution transparency is the phenomenon by which
distribution aspects in a system are hidden from users and applications.
Examples include access transparency, location transparency, migration
transparency, relocation transparency, replication transparency,
concurrency transparency, failure transparency and persistence
- What is an open distributed system and what benefits does
- An open distributed system is blablabla
- Describe precisely what is meant by a scalable system
- A system is scalable with respect to its number of components,
geographical size or number and size of administrative domains, if it can
grow in one or more of these dimensions without an unacceptable loss of
- Scalability can be achieved by applying different techniques.
What are these techniques?
- Distribution, replication and caching.
Chapter 1: hardware concepts
- What is the difference between a multiprocessor and a
- In a multiprocessor, the CPUs have access to a shared main
memory. There is no shared memory in multi-computer systems, the CPUs can
communicate only through message passing.
- What is the drawback of multiprocessor systems?
Bus, all trying to contact the
memory using the bus
Scalability is an issue
What is cache?
What is a problem with cache?
Consistency: local copy can be
- How can we improve this scalability issue?
Chapter 1: Software concepts
- What is the difference between a distributed operating system
and a network operating system?
- A distributed operating system manages multiprocessors and
homogenous multi-computers. A network operating system connects different
independent computers that each have their own
operating system so that users can easily use the services available on
Chapter 4: Naming
Naming play an
important role in all computer systems
They are used to
Uniquely identify entities
Refer to locations and so on
thus allows a process to access the named entity
To resolve names
it is necessary to implement a naming system
In a distributed
system the implementation of a naming system is itself often distributed across
distribution is done plays a key ole in the efficiency and scalability of the
concentrate on three different important ways that names are used in
Mangle noe her
A name space implementation slide 23 og
A name space
forms the heart og a naming service
A service that allows users and processes
to add, remove and lookup names
Distribute the name resolution process as well as name space management across
multiple machines bu distributing nodes of thenaming graph
hierarchical naming graph and distinguish three levels
Slide 28 Iterative name resolution
Slide 30 Recursive name resolution II
- An important issue in distributed systems is the replication of
data in order to
- Enhance reliability
- Improve performance
- One of the major problems is keeping replicas consistent
Reasons for replication: slide 4
Problems with replication: slide 5
Shared objects: slide 6
Strict consistency: slide 15, 16
Sequential consistency: slide 17, 18
Causal consistency: slide 21, 23
FIFO consistency: slide 25
Release consistency: 33
Monotonic reads: slide 46,
Read you writes: slide 53
Dependability: slide 5, 7
Terminology II: slide 9, 10
Failure masking: slide 14,15
Flat groups vs. hierarchical groups: slide
Reliable RPC II: Slide 27, 28, 30
Agreement in faulty systems: