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DRAFT y +1/1/60+ y Student ID (Matricola) 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 Computing Infrastructures Course 095897 P. Cremonesi, M. Gribaudo 08-09-2015 Last Name / Cognome: ................................................................. First Name / Nome: ................................................................. Answers must be given exclusively on the answer sheet (last sheet): DO NOT FILL ANY BOX IN THIS SHEET Students must use pen (black or blue) to mark answers (no pencil). Students are permitted to use a non-programmable calculator. Students are NOT permitted to copy anyone else’s answers, pass notes amongst themselves, or engage in other forms of misconduct at any time during the exam. Students are NOT permitted to use mobile phones and similar connected devices. Scores: correct answers +1 point, unanswered questions 0 points, wrong answers -0.333 points. Reserve questions must NOT be answered, unless explicitly stated during the exam. y For your examination, preferably print documents compiled from auto-multiple-choice. y DRAFT y +1/2/59+ y Disks A large company wants to set up a RAID 6+0, with10 groups of 6 disks each. All the disks are identical, and characterized by a capacity of1 TB, an M T T F = 1500 days and anM T T R = 20 days. Question 1 Which is the total capacity of the array? A 58 TB. B 40 TB. C 59 TB. D 50 TB. SOLUTION: Each group uses RAID 6, so of the 6 disks, only four contains useful data: each group has thus a capacity of 4 TB. The total capacity of the RAID 6+0 array is thus4 · 10 = 40 TB. Question 2 Which is the mean time to data loss of the system? A 14062, 5 days B 82, 189 days C 3906, 25 days D 84375 days SOLUTION: M T T DL= 2·15003 60·5·4·202 =…