CS245 Summer 1994 Handout #3 Assignment 1 due in class on Thursday June 30,1994. State all assumptions. Problem 1. (40 points) Consider a 5.25 inch disk with 16 magnetic surfaces rotating at 5400 rpm. It has a usable capacity of 1 gigabytes (2**30 bytes) stored on 1024 cylinders. Assume 20% of each track is used as overhead. a. What is the burst bandwidth this disk could support reading a single block from one track? b. What is the sustained bandwidth this disk could support reading an entire track? c. What is the average rotational latency, assuming it is not necessary to start at the beginning of the track? d. Assuming the average seek time is 15 ms, what is the average time to fetch a 4-Kbyte (2**12 bytes) block? Problem 2. (15 points) A Macintosh computer formats hard disks using a parameter called "interleaving," which specifies whether sequentially numbered blocks appear on the disk as every block, every other block, or every third block. a. Explain why this feature may be useful in some cases. b. Is this feature still useful if we use double buffering? c. Is this feature still useful if memory is not limited? Problem 3. (15 points) Give 3 reasons relational database management systems tend to use fixed-length records of fixed-length fields. Problem 4. (15 points) Do Problem 7.4 in Textbook. (First correct typo: First bullet should read: * Move record 6 to the space occupied by record 5 and move record 7 to the space occupied by record 6. ) Problem 5. (15 points) Do Problem 7.17 in Textbook.