Improving Networks Worldwide. UNH InterOperability Lab Serial Advanced Technology Attachment (SATA) Application Layer

2 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions * SSP and NCQ are SATA specific features that were added because of increased capability. These features are often tested by OEMs and the SATA-IO certification program.

3 SATA Application Layer Description of SSP Host configures a device when it is recognized using commands like SET FEATURES and SSP commands Software settings are retained after a software reset When a COMRESET occurs, not all settings are necessarily preserved as a COMRESET is essentially a hardware reset

4 SATA Application Layer Description of SSP If there is an asynchronous loss of signal, a COMRESET is sent, some software settings are lost Without legacy mode drivers, SSP ensures that settings are maintained after a COMRESET

5 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions

6 SATA Application Layer SET FEATURES SET FEATURES Definition Features Enable / Disable Values Feature Identification Values 1.Enable / Disable Non-Zero Offsets in DMA Setup 2.Enable / Disable DMA Setup FIS Auto-Activate Optimization 3.Enable / Disable Device-Initiated Interface Power State Transitions 4.Enable / Disable Guaranteed in-Order Data Delivery 5.Enable / Disable Asynchronous Notification 6.Enable / Disable Software Settings Preservation 7.Enable / Disable Device Automatic Partial to Slumber Transitions

7 SATA Application Layer SET FEATURES Definition SET FEATURES commands inform the device about host capabilities Features can be enabled and disabled The control of these features is designated by SET FEATURES

8 SATA Application Layer Features Enable / Disable Values Features(7:0) Value Description 10hEnable use of Serial ATA feature 90hDisable use of Serial ATA feature (7:0) contains the specific SATA feature that is being either enabled or disabled. These features are defined on the following slide.

9 SATA Application Layer Feature Identification Values Count(7:0) ValueDescription 00hReserved 01hNon-zero buffer offset in DMA Setup FIS 02hDMA Setup FIS Auto-Activate optimization 03hDevice-initiated interface power state transitions 04hGuaranteed In-Order Data Delivery 05hAsynchronous Notification 06hSoftware Settings Preservation 07hDevice Automatic Partial to Slumber transitions 08h - FFhReserved for future Serial ATA definition

10 SATA Application Layer Enable / Disable Non-Zero Offsets in DMA Setup Enables or disables non-zero buffer offsets in the DMA Setup FIS if device uses the First-party DMA mechanism When enabled, useful for completing incorrectly ordered data delivery

11 SATA Application Layer Enable / Disable DMA Setup FIS Auto-Activate Optimization Used to automatically activate the transfer of the first Data FIS from the host to the device Allows FIS operation to immediately activate, eliminating the need for a separate DMA Activation FIS

12 SATA Application Layer Enable / Disable Device-Initiated Interface Power State Transitions Allows host to enable or disable initiation of power state transitions for the device When interface power state transitions is favorable, host can enable for the device

13 SATA Application Layer Enable / Disable Device-Initiated Interface Power State Transitions Capture shows device response to PMREQ_P when IPM (Interface Power Management) is enabled

14 SATA Application Layer Enable / Disable Device-Initiated Interface Power State Transitions Capture shows device response to PMREQ_S when IPM (Interface Power Management) is NOT enabled

15 SATA Application Layer Enable / Disable Guaranteed in-Order Data Delivery Host can enable or disable guaranteed in-order data delivery when a First- party DMA mechanism and non-zero buffer offsets are used Helpful for segmenting cumbersome I/O processes into multiple data phases while keeping complexity at a minimum

16 SATA Application Layer Enable / Disable Asynchronous Notification Allows host to control asynchronous notification Disabled by default, when enabled allows the device to request attention without polling the host

17 SATA Application Layer Enable / Disable Software Settings Preservation Software Settings Preservation can be enabled or disabled by the host Supported by default at start up

18 SATA Application Layer Enable / Disable Device Automatic Partial to Slumber Transitions Host can enable or disable Device Automatic Partial to Slumber transitions Not enabled if the Device-Initiated Interface Power State transitions have been disabled

19 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions

20 SATA Application Layer Preserved Settings Across COMRESET The following settings are reserved across a COMRESET when a device has SSP enabled. INITIALIZE DEVICE PARAMETERS: Device settings established with the INITIALIZE DEVICE PARAMETERS command. This command is obsolete in the ATA8-ACS standard, and was last defined in the ATA/ATAPI-5 standard. Power Management Feature Set Standby Timer: The Standby timer used in the Power Management feature set. Read/Write Stream Error Log: The Read Stream Error Log and Write Stream Error Logs (accessed using the GPL feature set commands).

21 SATA Application Layer Preserved Settings Across COMRESET Security mode state: The security mode state established by Security Mode feature set commands (refer to the ATA8-ACS standard). The device shall not transition to a different security mode state based on a COMRESET. For example, the device shall not transition from the SEC5: Unlocked / not Frozen state to state SEC4: Security enabled / Locked when a COMRESET occurs, instead the device shall remain in the SEC5: Unlocked / not Frozen state. SECURITY FREEZE LOCK: The Frozen mode setting established by the SECURITY FREEZE LOCK command.

22 SATA Application Layer Preserved Settings Across COMRESET SECURITY UNLOCK: The unlock counter that is decrement as part of a failed SECURITY UNLOCK command attempt. SET MAX ADDRESS (EXT): The maximum LBA specified in SET MAX ADDRESS of SET MAX ADDRESS EXT. SET FEATURES (Write Cache Enable/Disable): The write cache enable/disable setting established by the SET FEATURES command with subcommand code of 02h or 82h.

23 SATA Application Layer Preserved Settings Across COMRESET SET FEATURES (Set Transfer Mode): PIO, Multiword, and UDMA transfer mode settings established by the SET FEATURES command with subcommand code of 03h. SET FEATURES (Advanced Power Management Enable/Disable): The advanced power management enable/disable setting established by the SET FEATURES command with subcommand code of 05h or 85h. The advanced power management level established in the Count(7:0) register when advanced power management is enabled (SET FEATURES subcommand code 05h) shall also be preserved.

24 SATA Application Layer Preserved Settings Across COMRESET SET FEATURES (Read Look-Ahead): The read look-ahead enable/disable setting established by the SET FEATURES command with subcommand code of 55h or AAh. SET FEATURES (Release Interrupt): The release interrupt enable/disable setting established by the SET FEATURES command with a subcommand code of 5Dh or DDh. SET FEATURES (SERVICE Interrupt): The SERVICE interrupt enable/disable setting established by the SET FEATURES command

25 SATA Application Layer Preserved Settings Across COMRESET SET FEATURES (Reverting to Defaults): The reverting to power-on defaults enable/disable setting established by the SET FEATURES command with a subcommand code of CCH or 66h. SET MULTIPLE MODE: The block size established with the SET MULTIPLE MODE command.

26 SATA Application Layer Preserved Settings Across COMRESET NCQ QUEUE MANAGEMENT (Deadline Handling): The state of WDNC and RDNC. Write-Read-Verify feature set: The contents of IDENTIFY DEVICE data word 120 bit 1, words , and word 220 bits (7:0). The device shall not return to its Write-Read-verify factory default setting after processing a COMRESET

27 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions

28 SATA Application Layer How NCQ Works When drive receives multiple commands from an application, NCQ optimizes how the commands will be completed Drive must intelligently and internally assess the destination of the logic block addresses and then order the commands to optimize the workload

29 SATA Application Layer How NCQ Works This is due to the fact that the mechanical movement needed to position the read / write head is relevant This improves performance and minimizes the mechanical positioning for the drive

30 SATA Application Layer How NCQ Works Commands are ordered in the queue to minimize mechanical movement

31 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions

32 SATA Application Layer Description of NCQ The reserved 32 bit field in the Set Device Bits FIS is used to show the status for outstanding commands, one command per bit BSY bit in the Status register shows only if the device is ready to receive another command

33 SATA Application Layer Description of NCQ When a new command is received the BSY bit is set to zero Data sent to the device uses the First Party DMA mechanism to allow the host to select the appropriate destination memory buffer for transfer Host cannot issue new commands from the reception of a DMA Setup FIS until either the the associated transfer count is exhausted OR the ERR bit in the Status register is set

34 SATA Application Layer Description of NCQ DMA Setup FIS for memory buffer selection

35 SATA Application Layer Description of NCQ Set Device Bits FIS for successful READ FPDMA QUEUED command

36 SATA Application Layer Description of NCQ Set Device Bits FIS with error notification and command completions

37 SATA Application Layer Description of NCQ Set Device Bits FIS aborting all outstanding commands

38 SATA Application Layer Description of NCQ Successful completion of this process is updated in the Set Device Bits FIS 32 bit array If process fails, the process is halted and allows software or controller firmware to resolve the failure

39 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions

40 SATA Application Layer Definitions Command Issue Mechanism Data Delivery Mechanism Status Return Mechanism Priority Unload

41 SATA Application Layer Command Issue Mechanism New commands can only be attempted when the BSY bit has been cleared to zero BSY bit in the Shadow Status register is checked before a new command is issued Commands are deferred if BSY bit is set to one

42 SATA Application Layer Command Issue Mechanism It is favorable for a device to minimize deferred commands, so the BSY bit should be cleared as soon as possible NCQ issues a tag that identifies a command Tag range is from 0 to 31

43 SATA Application Layer Command Issue Mechanism For devices that show a value less than 31 in their IDENTIFY DEVICE word 75, the host issues tags that are less than or equal to the reported value When a new NCQ command is issued the bit in the SActive register corresponding to the tag is set to one

44 SATA Application Layer Command Issue Mechanism If command is accepted, the BSY bit is set to zero

45 SATA Application Layer Data Delivery Mechanism DMA Setup FIS is used by the device in order to choose the correct transfer buffer Multiple DMA Setup FIS transmission are not required, even if the transfer spans more than one Data FIS

46 SATA Application Layer Data Delivery Mechanism The DMA Mechanism is optimized to eliminate one transaction Requested data is immediately sent after a request without the need for a DMA Activate FIS

47 SATA Application Layer Data Delivery Mechanism A device may return data for a command out of order if: 1.Host controller supports non-zero buffering and is enabled 2.AND if guaranteed in order data deliver is not supported OR is disabled

48 SATA Application Layer Data Delivery Mechanism The device may send more than one DMA Setup FIS to complete a particular I/O process if: 1.The host supports non-zero buffer offsets 2.Use of non-zero offsets is enabled 3.The device supports and has guaranteed in- order data delivery enabled

49 SATA Application Layer Data Delivery Mechanism DMA Setup FIS definition for memory buffer selection

50 SATA Application Layer Status Return Mechanism Is not interlocked with other commands Relies on one active command bit (ACT), the 32 protocol specific bits in the Set Device Bits FIS, to convey status of outstanding commands SActive field conveys command completion information for updating the ACT bit array

51 SATA Application Layer Status Return Mechanism Possible for multiple commands to indicate completion by the time the host checks the status Successful commands use these mechanism to indicate status The Queued Error Log is used to indicate failed commands

52 SATA Application Layer Priority Two values for NCQ commands: normal and high When the host needs a higher quality of service for a command, priority is set to high Preference is given to high priority commands; these commands are completed in a more timely fashion than normal commands

53 SATA Application Layer Priority Devices do not have to process all high priority commands before normal priority commands However, high priority requests should be processed in a more quickly than normal isochronous requests

54 SATA Application Layer Unload If a device is dropped, a mechanism must be in place to park the heads when NCQ commands are still outstanding This could cause physical damage to the heads or disks in the hard drive. The disks could break or shatter from an impact If the drive is writing at the time of impact, data could be corrupted

55 SATA Application Layer Unload A device can accept the IDLE IMMEDIATE command with the Unload Feature. If this command is received the device shall: 1.Unload/park the heads immediately 2.Respond to the host with a Register - Device to Host FIS with the ERR bit set to one in the Status register since this is a non-queued command

56 SATA Application Layer Unload When an error is acknowledged, the host should read the Queued Error Log to see if the error was in receiving or executing the UNLOAD After the Error Log is read the NCQ error is cleared

57 SATA Application Layer Intermixing Non-Native Queued Commands and Native Queue Commands Host cannot issue a non-native queued command while a NCQ command is unfinished If a command is received while a NCQ command is outstanding, and error condition is sent (ERR and ABRT bits are set to one)

58 SATA Application Layer Intermixing Non-Native Queued Commands and Native Queue Commands All outstanding NCQ commands are aborted after an error and the device performs a clean up state All bits in the SActive field are set to one when the register is cleared After reading the error log, the device executes all queued commands regardless of errors

59 SATA Application Layer Application Layer SATA Software Settings Preservation (SSP) – Description of SSP – SET FEATURES – Preserved Settings Across COMRESET SATA Native Command Queuing (NCQ) – How NCQ Works – Description of NCQ – Definitions