Architecture (DMX)
- Workload through the front end director
- When IO comes in through the FE director it is assigned a Q-Record
- Q-Record is used to trace IO through the system, identifier for that IO
- Microcode is a task based OS
- Can trace Q-Record from FE director to Global Memory (CACHE), can determine how long it took to get there as well
- Keep data in CACHE as long as we can, makes the system faster
- Marked write pending - cbit flag - write in cache
- Can be destaged to back end (BE) or disks
- As long as data is getting read or written to cache time stamps are updated and it remains in cache
- DA write pending limit / CACHE prep - 50% CACHE write pending limit is reached then the system prioritizes destaging data out of cache to the same level as receiving writes
- Hard coded ports which are requirements for the FE and BE
- Monolithic cards (director)
- Directors were cards attached to the box
- Enclosure had two directors
Director Back End
- 4 DA ports
- Broken out into different emulations
- BE does data services for BE - RDF
- 4 slices with 2 ports that does interfacing to physical disks
- Disks are 2 ports with FC Arbitrated Loop
- DA is responsible for data rebuilds, disk scrubbing and other tasks for maintaining health and integrity
- Director Emulation is important to know and ensure you're working with the correct systems
- Single Emulation for DA