Stores the most-recently accessed blocks on block devices. This avoids having to re-read the blocks from the physical device.
The buffer cache is a hash table of buffers, indexed by device and block number. LRU lists are maintained for the buffers in the various states, with separate lists for buffers of different sizes. With 2.3's unification of the buffer and page caches, each buffer head points to part or all of a page structure, through which the buffer's actual contents are available. FIXME
A temporary data storage area used to enhance drive performance. Larger buffer cache size can result in improved drive performance.
a crucial part of an operating system kernel, it is in charge of keeping all buffers up to date, shrinking the cache when needed, clearing unneeded buffers and more. See buffers.
A buffer cache is supplied by the kernel and contains file system block-sized buffers. Block device drivers use these buffers in I/O operations.
The portion of the SGA that holds copies of Oracle data blocks. All user processes that connect to an instance share access to the buffer cache. Performance of the buffer cache is indicated by the BCHR (Buffer Cache Hit Ratio). The buffers in the cache are organized in two lists: the dirty list and the least recently used (LRU) list. The dirty list holds dirty buffers, which contain data that has been modified but has not yet been written to disk. The least recently used (LRU) list holds free buffers (unmodified and available), pinned buffers (currently being accessed), and dirty buffers that have not yet been moved to the dirty list.