Small Computer System Interface
From Unofficial BOINC Wiki
One of the interconnection mechanisms used to connect a Disk Drive to the computer system. Normally reserved for higher end systems because of the greater amount of intelligence built into the controller and the disk drive itself. These features allow the SCSI system to schedule the reads and writes to the disk surface in the most "cost-effective" order, with each new request being properly inserted into the schedule. This management of the read and write tasks can give the disk drive a significantly improved response over other disk drive systems.
As with all standards there are varieties of SCSI buses with later generations increasing the speed and carrying capacity of the interconnect. The older SCSI standard used 50-pin interconnects and speeds now considered to be very slow. Later generations increased the speed to 160 MegaBytes per second with wider data paths. Newer generations should double that (if they have not already done so). Also, there are variants that are using serial technologies to transfer data between the computer and the attached disk drive.