· 3 operational steps of computer systems· 5 functional units of computer systems· Server· SupercomputingServer?· Machine’s view point: Equipped with very powerful processing unit, huge main...

· 3 operational steps of computer systems · 5 functional units of computer systems · Server · 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 server What is the first action your computer has to take when you type www.google.com on your browser? 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 (123-45-6789) Name (Jinsuk Baek) IP (126.21.10.8) Domain name (www.google.com) Google server DNS Server D.N IP addr. google 126.21.10.8 facebook 152.15.234.86 ….. ….. Your PC www.google.com 126.21.10.8 Convert this to binary 01111110000101010000101000001000 32 bits Requirements of Server: · Reliable · Available · Scalable · Secure Supercomputer Supercomputing Technology Supercomputer vs. Desktop 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 (%) Probability (Decimal) X (1/100) % X (1/100) 10% 10 X (1/100) 10/100 0.1 30% 30 X (1/100) 30/100 0.3 90% 90 X (1/100) 90/100 0.9 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? Dice 1, 2, 3, 4, 5, 6 6 cases Coin Front, Back 2 cases 6 X 2 = 12 cases What is a probability that there is no available computing resource for me at the same time? What 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 = 0.00001 What is a probability that there are at most 2 active computer systems? What 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 (0.1)0 X (0.9)5 + 5 X (0.1)1 X (0.9)4 + 10 X (0.1)2 X (0.9)3 nCr = 5C0 = = = 1 5C1 = = = 5 5C2 = = = 10 Probability that there is no active computer 5C0 X (0.1)0 X (0.9)5 = 1 X (0.1)0 X (0.9)5 0.9 X 0.9 X 0.9 X 0.9 X 0.9 = (0.1)0 X (0.9)5 Probability that there is 1 active computer 5C1 X (0.1)1 X (0.9)4 = 5 X (0.1)1 X (0.9)4 0.1 X 0.9 X 0.9 X 0.9 X 0.9 = (0.1)1 X (0.9)4 + 0.9 X 0.1 X 0.9 X 0.9 X 0.9 = (0.1)1 X (0.9)4 + 0.9 X 0.9 X 0.1 X 0.9 X 0.9 = (0.1)1 X (0.9)4 + 0.9 X 0.9 X 0.9 X 0.1 X 0.9 = (0.1)1 X (0.9)4 + 0.9 X 0.9 X 0.9 X 0.9 X 0.1 = (0.1)1 X (0.9)4 Probability that there are 2 active computers 5C2 X (0.1)2 X (0.9)3 = 10 X (0.1)2 X (0.9)3 0.1 X 0.1 X 0.9 X 0.9 X 0.9 = (0.1)2 X (0.9)3 + 0.1 X 0.9 X 0.1 X 0.9 X 0.9 = (0.1)2 X (0.9)3 + 0.1 X 0.9 X 0.9 X 0.1 X 0.9 = (0.1)2 X (0.9)3 + 0.1 X 0.9 X 0.9 X 0.9 X 0.1 = (0.1)2 X (0.9)3 + 0.9 X 0.1 X 0.1 X 0.9 X 0.9 = (0.1)2 X (0.9)3 + 0.9 X 0.1 X 0.9 X 0.1 X 0.9 = (0.1)2 X (0.9)3 + 0.9 X 0.1 X 0.9 X 0.9 X 0.1 = (0.1)2 X (0.9)3 + 0.9 X 0.9 X 0.1 X 0.1 X 0.9 = (0.1)2 X (0.9)3 + 0.9 X 0.9 X 0.1 X 0.9 X 0.1 = (0.1)2 X (0.9)3 + 0.9 X 0.9 X 0.9 X 0.1 X 0.1 = (0.1)2 X (0.9)3 There is no active computer + There is 1 active computer + There are 2 active computers 1 X (0.1)0 X (0.9)5 + 5 X (0.1)1 X (0.9)4 + 10 X (0.1)2 X (0.9)3 = 0.59049 + 0.32805 + 0.0729 = 0.99144 99.144% 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