Design a backup strategy for a computer system. One option is to use plug-in external disks, which cost $150 for each 500 GB drive. Another option is to buy a tape drive for $2500, and 400 GB tapes for $50 apiece. (These were realistic prices in 2008.) A typical backup strategy is to have two sets of backup media onsite, with backups alternately written on them so in case the system fails while making a backup, the previous version is still intact. There's also a third set kept offsite, with the offsite set periodically swapped with an on-site set.
a. Assume you have 1 TB (1000 GB) of data to back up. How much would a disk backup system cost?
b. How much would a tape backup system cost for 1 TB?
c. How large would each backup have to be in order for a tape strategy to be less expensive?
d. What kind of backup strategy favors tapes?