Native Command Queuing

Abstract: Methods and apparatus for host-side Serial ATA Native Command Queuing (NCQ) tag management are disclosed. In one aspect, an exemplary apparatus may include a memory and an NCQ tag selection circuit in communication with the memory. The memory may store information for each of a plurality of different NCQ tag values. The information for each NCQ tag value may indicate whether or not a command having the NCQ tag value has been issued. The NCQ tag selection circuit may examine the information in the memory, and may select an NCQ tag value having information that indicates that a command having the NCQ tag value has not been issued. Systems and architectures including such apparatus are also disclosed.

Abstract: This paper describes a new key feature of SATA standard, native command queuing (NCQ). This feature is specific to the SATA interface but is similar in some ways to other reordering protocols developed for the small computer system interface (SCSI). Building a queue is the first component of this protocol. The drive must know when it receives a command whether it should queue the command or whether it should execute that command immediately. NCQ uses a new command protocol with new command opcodes that allows the device to know whether a command can be queued. Thus NCQ is more beneficial to the home PC environment, providing the storage subsystem with better performance for today's end-user requirements as media accessibility and the use of multiple applications simultaneously becomes a more commonplace event in the digital home.

Abstract: The present invention is directed to a method and apparatus of automatic power management control for Serial ATA interface. In an exemplary aspect of the present invention, an idle or active condition of a Serial ATA interface including a NCQ Serial ATA device is automatically detected. In this step, it is determined, preferably based on a value of the FPDMA (First Party Direct Memory Access) bit in a Task File Ram of the Serial ATA interface, whether the NCQ Serial ATA device is in a FPDMA Data Phase. When the NCQ Serial ATA device is in a FPDMA Data Phase, the Serial ATA interface is active (i.e., not idle). When Serial ATA is in an idle condition, idle time of Serial ATA interface is measured using a power down counter whose frequency is determined by a programmable register based on an input clock. When a power down counter value is equal to a first value, a request for a Partial power state is asserted, and Serial ATA interface is put into a Partial power state. When a power down counter value is equal to a second value, a request for a Slumber power state is asserted, and Serial ATA interface is put into a Slumber power state.

Abstract: This paper describes Groundhog, an open-source SATA host bus adapter (HBA) for FPGAs. This system makes it easy for FPGA-based applications to directly interact with permanent storage devices. This allows reconfigurable computing devices to be used in new applications that require bulk storage and presents additional opportunities to increase performance, reduce power consumption and improve system integration. In addition to standard disk sector read/write commands, this framework also supports more advanced concepts such as native command queuing (NCQ) introduced with SATA II. We test the system with latest-generation SSDs and demonstrate the potential performance advantages and trade-offs of direct hardware access to bulk storage devices.