In the last section, we noted that

In the last section, we noted that order taking, credit checking, warehousing, and shipping
are manual operations as illustrated in Figure 9.1. The figure also illustrates a fifth
operation—data processing. This is an automated operation and is discussed in this section
in greater detail. The computer system described here is an example of a legacy system
that employs the sequential file structure for its accounting records. Both tapes and
disks can be used as the physical storage medium for such systems. However, the use of
tapes has declined considerably in recent years. For day-to-day operations, tapes are inefficient
because they must be physically mounted on a tape drive and then dismounted
when the job ends. This approach is labor intensive and expensive. The constant decline
in the cost of disk storage in recent years has eliminated the economic advantage once
associated with tapes. Most organizations that still use sequential files store them on
disks that are permanently connected (online) to the computer system and require no
human intervention. The operational features of sequential files described earlier are the
same for both tape and disk media. Today, tapes are used primarily as backup devices
and for storing archive data. For these purposes, they provide an efficient and effective
storage medium for a large system.