Accounting Information Systems 8th Edition by James Hall

Exercise 90

BACKUP AND RECOVERY PROCEDURES FOR DIRECT ACCESS FILES
Figure 3-10 provides a backup and recovery system for files that are updated using a destructive update approach. Now think about a specific situation that might use this approach. A company creates its sales order transaction file in batches. Once a day, a sales clerk compiles a transaction file by entering data from the previous day's sales orders to the transaction file. When these transactions have all been entered and the transaction file passes editing, the transaction file is used to destructively update both the sales and the accounts receivable master files. Each of these master files is then backed up to a magnetic tape. The magnetic tapes are stored (offline) in a remote location. Now consider what might happen if, in the middle of an update of the sales master file, lightning hit the company's building, resulting in a power failure that caused the computer to corrupt both the transaction file and the master files.
a. Which, if any, files contain noncorrupted data (transaction file, accounts receivable master file, sales master file, or backup master files)?
b. Will a clerk have to re-enter any data? If so, what data will have to be re-entered?
c. What steps will the company have to take to obtain noncorrupted master files that contain the previous day's sales data?