:PROPERTIES: :ID: 6793b7a4-1791-480b-9163-0e72683bcc4a :mtime: 20240525073702 :ctime: 20240525073701 :END: #+title: buffer cache #+filetags: :public:operatingsystems:project: * Buffer Cache Maintain copies of some parts of disk in memory for speed ** Reading then involves - Locate relevant blocks from inode - Check if in buffer cache - If not, read from disk into buffer cache memory - Return data from buffer cache ** Writing is the same except final step updates the version in the cache - “Typically” prevents majority (around 85%) of implied disk transfers - But at risk of losing data while the update is only in the buffer cache ** Must periodically flush dirty buffers to disk - Can cache metadata too but what problems can that cause