Assume that (i) the size of each disk block is 8KB, (ii) the probability that the buffer manager can handle a data request without accessing the disk (i. e., the probability that a requested block is already in the buffer) is 90%, (iii) only 10% of disk block accesses require a disk seek (i. e., 90% of the disk blocks are read consecutively without requring any disk seek), (iv) no disk blocks are updated (i. e., no need to write dirty blocks back to the hard drive), and (v) the time spent for reading/writing data in the main memory is negligible (considered 0 milliseconds). Under these assumptions, calculate the expected data access time (i. e., how much time it would on average take to obtain a disk block from the buffer manager).

When you type the pwd command, you notice that your current location on the linux filesystem is the /usr/local directory. answer the following questions, assuming that your current directory is /usr/local for each question. a. which command could you use to change to the /usr directory using an absolute pathname? b. which command could you use to change to the /usr directory using a relative pathname? c. which command could you use to change to the /usr/local/share/info directory using an absolute pathname? d. which command could you use to change to the /usr/local/share/info directory using a relative pathname? e. which command could you use to change to the /etc directory using an absolute pathname? f. which command could you use to change to the /etc directory using a relative pathname?