Disk and File Summary
Disks provide cheap, non-volatile storage.
- Random access, but cost depends on location of page on disk; important to arrange data sequentially to minimize seek and rotation delays.
Buffer manager brings pages into RAM.
- Page stays in RAM until released by requestor(s).
- Written to disk when frame chosen for replacement (which is after all requestors release the page).
- Choice of frame to replace based on replacement policy.
- Tries to pre-fetch several pages at a time.