Seagate ST3250824SV Manuale Utente
40
SV35 Series SATA Product Manual, Rev. C
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.
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 com-
mand, 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, as should the starting LBA of any streaming com-
mand.
mand, 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, as should the starting LBA of any streaming com-
mand.
Urgent bit
The Urgent bit in the READ STREAM and WRITE STREAM commands is ignored. Therefore, bits 9 and 10 of
IDENTIFY DEVICE data words 84 and 87 shall remain clear.
IDENTIFY DEVICE data words 84 and 87 shall remain clear.
Flush to Disk bit
The Flush to Disk bit in the WRITE STREAM command specifies that all data for the specified stream shall be
flushed to the media before posting command completion. If a host requests flushes at times other than the
end of each Allocation Unit, streaming performance may be degraded. Using the SET FEATURES command
to enable/disable caching may not affect caching for streaming commands.
flushed to the media before posting command completion. If a host requests flushes at times other than the
end of each Allocation Unit, streaming performance may be degraded. Using the SET FEATURES command
to enable/disable caching may not affect caching for streaming commands.
Not Sequential bit
The Not Sequential bit specifies that the next LBA(s) after those requested in the current READ STREAM com-
mand are not anticipated to be used in a subsequent READ STREAM command. This information may help
the device with pre-fetching decisions.
mand are not anticipated to be used in a subsequent READ STREAM command. This information may help
the device with pre-fetching decisions.
Read Continuous bit
If the Read Continuous bit is set to 1 for the command, the device shall attempt to transfer the requested
amount of data to the host within the Command Completion Time Limit even if an error occurs. The data sent to
the host by the device in an error condition is vendor specific.
amount of data to the host within the Command Completion Time Limit even if an error occurs. The data sent to
the host by the device in an error condition is vendor specific.
Write Continuous bit
If the Write Continuous bit is set to 1 for the command and an error is encountered, the device shall still attempt
to complete the transfer within the requested time. If an error occurs and cannot be resolved within the Com-
mand Completion Time Limit, the erroneous section on the media may be unchanged or may contain unde-
fined data. A future read of this area may not report an error, even though the data is erroneous. If the Flush Bit
is set to 1 on the STREAM WRITE command and the data cannot successfully be written to the media, then
the drive will report a Stream Error on the command.
to complete the transfer within the requested time. If an error occurs and cannot be resolved within the Com-
mand Completion Time Limit, the erroneous section on the media may be unchanged or may contain unde-
fined data. A future read of this area may not report an error, even though the data is erroneous. If the Flush Bit
is set to 1 on the STREAM WRITE command and the data cannot successfully be written to the media, then
the drive will report a Stream Error on the command.
Handle Streaming Error bit
The Handle Streaming Error bit specifies to the drive that this command starts at the LBA of a recently reported
error section, so the device may attempt to continue its corresponding error recovery sequence where it left off
earlier. This mechanism allows the host to schedule error recovery and defect management for content critical
data.
error section, so the device may attempt to continue its corresponding error recovery sequence where it left off
earlier. This mechanism allows the host to schedule error recovery and defect management for content critical
data.