Understanding Discord NSFW Servers A Guide for Responsible Users.pdf
Distributed Systems
1. EEDC
Execution
34330
Environments for Distributed Systems
Distributed
Computing
Master in Computer Architecture,
Networks and Systems - CANS
Homework number: 1
Group number: EEDC-1
Group members:
Hugo Pérez – vhpvmx@gmail.com
Sergio Mendoza – sergiomendo@gmail.com
Carlos Fenoy – carles.fenoy@gmail.com
2. Definition
You know you have a distributed systems when the crash
of a computer you have never heard of stops you from
getting any work done. - Lamport
A collection of independent computers that
appears to its users as a single coherent
system. - Tanenbaum
3. Definition
A distributed system consists of a collection of
autonomous computers, connected through a network
and distribution middleware, which enables computers to
coordinate their activities and to share the resources of
the system, so that users perceive the system as a single,
integrated computing facility.
6. Characteristics
Challenges:
● Heterogeneity
● Transparency
● Fault tolerance and failure management
● Scalability
● Concurrency
● Openness and Extensibility
● Migration and load balancing
● Security
7. Characteristics
Transparency:
● Entire distributed system should appear as a single unit
● Complexity interactions between the components should
be typically hidden from the end user.
(For the user)
9. Characteristics
Scalability:
● System should work efficiently with increasing number
of users
● Addition of a resource should improve the
performance of the system.
++ --
11. Characteristics
Openness & Extensibility:
● Interfaces should be cleanly separated and publicly
available to enable easy extensions to existing
components and add new components.
12. Characteristics
Security:
● Access to resources should be secured
● Only known users are allowed to access
13. Middleware
What is middleware?:
● Software layer between the operating system and
the applications on each site of the system.
14. Middleware
What Middleware offers?:
● Hiding distribution
● Hiding the heterogeneity
● Providing uniform, standard, high-level interfaces to
the application developers and integrators
15. Middleware
How it works?
● Client-side interface invoke functions that the
middleware provides
17. Examples
Search Engines
● Google has 36 data centers across the globe. With 150
racks 40 servers per data center, that would mean
Google has more than 200,000 servers. This enables a
sub-half-second response to an ordinary Google search
query that involves 700 to 1,000 servers.
CNet News, May 30 2008
19. Examples
Online Games
● World of Warcraft
■ 20,000 computer systems
■ 13,250 server blades
■ 75,000 CPU cores
■ 1.3 petabytes of storage
■ 4,600 staffers
● Taikodom (a Brazilian gaming startup) use
a combination of a z9 mainframe to
handle transactions connected using a Gigabit
Ethernet to a cluster of blade servers with Cell
processors for graphics.
21. Examples
Twitter (March 14, 2011)
#tweets
● 3 years, 2 months and 1 day. The time it took from the first Tweet
to the billionth Tweet.
● 1 week. The time it now takes for users to send a billion Tweets.
● 50 million. The average number of Tweets people sent per day,
one year ago.
● 140 million. The average number of Tweets people sent per day, in
the last month.
● 177 million. Tweets sent on March 11, 2011.
● 456. Tweets per second (TPS) when Michael Jackson died on June
25, 2009 (a record at that time).
● 6,939. Current TPS record, set 4 seconds after midnight in Japan
on New Year’s Day.