Disk Interface
- Disk controller controls the hardware and mediate access
- Processor and disk are often connected by bus
- Multiple devices contend for the bus
Features
Disconnect from bus during request
Command queueing
- Give disk multiple requests
- Disk can make scheduling decisions using current position of read/write head
Disk cache used for read-ahead - Assuming sequential reads
Write caching - Don’t write everytime
- Cache some writes and write together later