- Devices connected together using phys. A phy is a connection to a physical link.
- Port = group of one or more phys that share a common address. A port can be connected to multiple other ports as physical links will allow.
- SSP = Serial SCSI Protocol -> communication between initiator and SAS device.
- STP = Serial Tunneling Protocol -> communication between SAS host and SATA target.
- SMP = Serial Management Protocol -> management of expanders and the service delivery subsystem.
- Expanders can host up to 128 devices, but can also be cascaded to support up to 16385 devices.
- Device = initiator, target, expander, or anything else that can be addressed (including virtually).
- Expander routing:
- Direct = when device is directly attached to expander.
- Table = when device is known to expander via one of its phys/ports, not direct-attach.
- Subtractive = not directly attached or routing table missing/no entry.
- Types of expanders:
- Fanout = addresses of all devices in the domain known to expander. Uses direct or table routing, no subtractive routing.
- Edge = devices known to expander are direct-attach only. Uses subtractive routing for unknown addresses, table routing or direct addressing for knowns. Can have 0 or 1 subtractive ports.
- Edge expander device sets = combination of fanout and edge working as one unit; follows edge expander rules.
- Domain = contains all devices that can directly interface; logical representation of devices.
- An expander without zoning can only exist in one domain; devices with multiple ports can exist in more than one domain.
Thursday, October 19, 2006
Tech: Serial-Attached SCSI Overview Notes (Part I)
SAS is the latest in storage technology. First there was IDE, then ATAPI, then SCSI and Fibre-Channel, then SATA. SAS is backward compatible with SATA and implements SCSI commands.
Posted by Jubz at 11:28 AM