· 3 operational steps of computer systems
· 5 functional units of computer systems
· Serve
· Supercomputing
Server?
· Machine’s view point: Equipped with very powerful processing unit, huge main memory, and fast I/O devices to support very high-performance computation.
· Service’s view point: Big database, equipped with capability to handle multiple simultaneous requests from its client computers.
Example) Consider DNS serve
What is the first action your computer has to take when you type www.google.com on your
owser?
Contact DNS server to get an IP address of the given domain name.
You know my name but you need my telephone number to call me.
You typed domain name (google.com) but your computer needs IP address of google.com
Human being likes to use mnemonic expression but machine likes to use numeric expression.
Numeric expression vs. Mnemonic expression
-------------------------------------------------------------------
SSN XXXXXXXXXX XXXXXXXXXXName (Jinsuk Baek)
IP XXXXXXXXXX) XXXXXXXXXXDomain name (www.google.com)
XXXXXXXXXXGoogle serve
XXXXXXXXXXDNS Serve
D.N
IP addr.
google
XXXXXXXXXX
facebook
XXXXXXXXXX
…..
…..
XXXXXXXXXXYour PC
XXXXXXXXXXwww.google.com
XXXXXXXXXX XXXXXXXXXXConvert this to binary
XXXXXXXXXX011111100001 XXXXXXXXXX 32 bits
Requirements of Server:
· Reliable
· Available
· Scalable
· Secure
Supercomputer Supercomputing Technology
Supercomputer XXXXXXXXXXvs. XXXXXXXXXXDesktop PC
$1 million $1000
(X 50 performance)
Supercomputing technology
Parallel Cluster Computing
· Need space equipped with AC 24/7
· Need operator to reside in the server room
· Introduce additional maintenance cost
Distributed Grid Computing
· Eliminate space limitation of parallel cluster computing
· What about the performance?
· Need conditions
· Network bandwidth should be very sufficient and its associated network speed is fast enough
· Most of computer systems are in idle status in most of time
Assumption:
· 10% of time Active Busy status
· 90% of time Inactive Idle status
Performance analysis for feasibility of distributed grid computing:
Let us consider the following five computer systems and its probability distribution in terms of activity.
PC1
PC2
PC3
PC4
PC5
Active (Busy)
10% (= 0.1)
10% (= 0.1)
10% (= 0.1)
10% (= 0.1)
10% (= 0.1)
Inactive (Idle)
90% (= 0.9)
90% (= 0.9)
90% (= 0.9)
90% (= 0.9)
90% (= 0.9)
Percentage (%) XXXXXXXXXXProbability (Decimal)
XXXXXXXXXXX (1/100)
% X (1/100)
10% 10 X (1/ XXXXXXXXXX/ XXXXXXXXXX
30% 30 X (1/ XXXXXXXXXX/ XXXXXXXXXX
90% 90 X (1/ XXXXXXXXXX/ XXXXXXXXXX
In probability, “AT THE SAME TIME” interpret as “AND” ( Multiplication).
Example) Let us toss a dice (on left hand) and a coin (on right hand) at the same time. How many different cases we will have?
XXXXXXXXXXDice 1, 2, 3, 4, 5, 6 6 cases
XXXXXXXXXXCoin Front, Back 2 cases
XXXXXXXXXX6 X 2 = 12 cases
What is a probability that there is no available computing resource for me at the same time?
XXXXXXXXXXWhat happens in this case? All five computers are in busy status at the same time.
(PC1 is active) X (PC2 is active) X (PC3 is active) X (PC4 is active) X (PC5 is active)
= 0.1 X 0.1 X 0.1 X 0.1 X 0.1 = XXXXXXXXXX
What is a probability that there are at most 2 active computer systems?
XXXXXXXXXXWhat happens in this case? There will be at least 3 available computer systems for me.
There is no active computer + There is 1 active computer + There are 2 active computers
1 X XXXXXXXXXXX (0.9)5
+
5 X XXXXXXXXXXX (0.9)4
+
10 X XXXXXXXXXXX (0.9)3
nCr =
5C0 = = = 1
5C1 = = = 5
5C2 = = = 10
Probability that there is no active computer 5C0 X XXXXXXXXXXX (0.9)5 = 1 X XXXXXXXXXXX (0.9)5
0.9 X 0.9 X 0.9 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)5
Probability that there is 1 active computer 5C1 X XXXXXXXXXXX (0.9)4 = 5 X XXXXXXXXXXX (0.9)4
0.1 X 0.9 X 0.9 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)4
+
0.9 X 0.1 X 0.9 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)4
+
0.9 X 0.9 X 0.1 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)4
+
0.9 X 0.9 X 0.9 X 0.1 X 0.9 = XXXXXXXXXXX (0.9)4
+
0.9 X 0.9 X 0.9 X 0.9 X 0.1 = XXXXXXXXXXX (0.9)4
Probability that there are 2 active computers 5C2 X XXXXXXXXXXX (0.9)3 = 10 X XXXXXXXXXXX (0.9)3
0.1 X 0.1 X 0.9 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.1 X 0.9 X 0.1 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.1 X 0.9 X 0.9 X 0.1 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.1 X 0.9 X 0.9 X 0.9 X 0.1 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.1 X 0.1 X 0.9 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.1 X 0.9 X 0.1 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.1 X 0.9 X 0.9 X 0.1 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.9 X 0.1 X 0.1 X 0.9 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.9 X 0.1 X 0.9 X 0.1 = XXXXXXXXXXX (0.9)3
+
0.9 X 0.9 X 0.9 X 0.1 X 0.1 = XXXXXXXXXXX (0.9)3
There is no active computer + There is 1 active computer + There are 2 active computers
1 X XXXXXXXXXXX (0.9)5
+
5 X XXXXXXXXXXX (0.9)4
+
10 X XXXXXXXXXXX (0.9)3
= XXXXXXXXXX XXXXXXXXXX = XXXXXXXXXX% More than 99%
More than 99% of time, there are at least 3 computer resources for me.
Probability Time domain (1 day)
1 minute = 60 seconds
1 hour = 60 minutes = 60 X 60 seconds = 3600