How Does IRIX DMF Work?
Migration steps:
1) user process issues read
2) XFS notices file is offline
3) Process sleeps
4) DMF sends recall request via DMAPI
5) DMF determines residence
6) DMF sends request to MSP
7) MSP restores data
8) MSP responds to DMF daemon
9) DMF responds to kernel
10) Kernel wakes process
Considerations:
- unscheduled interrupts
- multiple requests
- atomic database references