Figure 6-4. There is a one-to-one relationship between a buffer header (BH 100), its cached buffer (CB 330), and its on-disk data block (DBA 5,320). List manipulation occurs at the buffer header level, buffer changes occur in the cached buffer, and block changes occur at the disk level.

Have you ever wondered why there is no view v$bc for the buffer cache? That's because a buffer and a block's metadata are stored in the buffer header, and it's the metadata we usually need for our performance analysis. So the view is named v$bh, for buffer header.

* Cache buffers chains (CBCs) are used to quickly determine if an Oracle block resides in the buffer cache.