Streaming Feature Set; Streaming Commands - Hitachi HDS723020BLA642 Specifications

Support of the 48-bit Address feature set is indicated in the Identify Device response bit 10 word 83. In addition,
the maximum user LBA address accessible by 48-bit addressable commands is contained in Identify Device
response words 100 through 103.
When the 48-bit Address feature set is implemented, the native maximum address is the value returned by a
Read Native Max Address Ext command. If the native maximum address is equal to or less than 268,435,455, a
Read Native Max Address shall return the native maximum address. If the native maximum address is greater
than 268,435,455, a Read Native Max Address shall return a value of 268,435,455.

9.13 Streaming feature Set

The Streaming feature set is an optional feature set that allows a host to request delivery of data from a
contiguous logical block address range within an allotted time. This places a priority on time to access the data
rather than the integrity of the data. Streaming feature set commands only support 48-bit addressing.
A device that implements the Streaming feature set shall implement the following minimum set of commands:

Configure Stream

Read Stream PIO

Write Stream PIO

Read Stream DMA

Write Stream DMA

Read Log Ext
Support of the Streaming feature set is indicated in Identify Device work 84 bit 4.
Note that PIO versions of these commands limit the transfer rate (16.6 MB/s), provide no CRC protection, and
limit status reporting as compared to a DMA implementation.
9.13.1

Streaming commands

The streaming commands are defined to be time critical data transfers rather than the standard data integrity
critical commands. Each command shall be completed within the time specified in the Configure Stream
command or in the streaming command itself in order to ensure the stream requirements of the AV type
application. The device may execute background tasks as long as the Read Stream and Write Stream command
execution time limits are still met.
Using the Configure Stream command, the host may define the various stream properties including the default
Command Completion Time Limit (CCTL) to assist the device in setting up its caching for best performance. If
the host does not use a Configure Stream command, the device shall use the CCTL specified in each streaming
command, and the time limit is effective for one time only. If the CCTL is not set by Configure Stream command,
the operation of a streaming command with a zero CCTL is device vendor specific. If Stream ID is not set by a
Configure Stream command, the device shall operate according to the Stream ID set by the streaming
command. The operation is device vendor specific.
The streaming commands may access any user LBA on a device. These commands may be interspersed with
non-streaming commands, but there may be an impact on performance due to the unknown time required to
complete the non-streaming commands.
The streaming commands should be issued using a specified minimum number of sectors transferred per
command, as specified in word 95 of the Identify Device response. The transfer length of a request should be
a multiple of the minimum number of sectors per transfer.
The host provided numeric stream identifier, Stream ID, may be used by the device to configure its resources to
support the streaming requirements of the AV content. One Stream ID may be configured for each read and
write operation with different command completion time limits be each Configure Stream command.
Hitachi hard disk drive specifications
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