This report cites a survey noting that the percentage of terabyte-sized Oracle databases increased 18%, with 31% of DBA's reporting terabyte Oracle databases. The most important note in this survey is that the large database are suffering from chronic performance issues related to the high data volumes.
According to the study, 60 percent of the 335 members of the Chicago-based IOUG reported that a lack of available storage has affected database performance, with others saying that they have delayed application rollouts because of a lack of storage resources.
Oracle has many underutilized features for very large databases, including partitioning and data caching that help resolve data-volume related performance problems, and properly implemented,
Oracle database can grow into multi-terabyte size without any performance degradation.