FUJITSU MCM3064AP User Manual
Page 87
4.4 Various Processes
C156-E227-01EN
4-17
When the cache is enabled, the buffer contains data transferred from the host with
a write command. If a read command is issued to the sector address at this time,
the ODD directly transfers data to the high-level equipment from the data buffer
without reading it from media. If the cache is hit with a read command, the ODD
makes the data in the hit segment being kept in the highest priority.
The data listed below cannot be stored in the read cache.
•
Data that is transferred to a host during pre-reading
•
Data that is being read before hardware/software reset, DEVICE RESET
command reception, or the power-off sequence
•
Data already stored before media is mounted
All buffer data is discarded under the following conditions:
•
At hardware/software reset, DEVICE RESET command reception, or power-
off
•
When media is ejected
•
When the FORMAT UNIT command is received
•
In idle mode
•
In standby mode
•
In sleep mode
•
When the system receives the MODE SELECT and SET FEATURES
command that may change the reading mode
4.4.5.3 MO write cache
When the write cache is enabled, the ODD responds to the host with command
end. This occurs when the data transfer is done with the WRITE (10), WRITE
(12), or WRITE AND VERIFY command (hereafter "Write command" in this
document).
When the Write command is issued consecutively, the ODD responds to the host
with command end. This occurs if the specified sector logically contiguous to the
sector specified by the previous command operation, at the end of the succeeding
data transfer.
The ODD writes data kept in the buffer to media under the following conditions:
•
When data can be written to media during data transfer processing with a
write command or in the command wait state
•
When all data buffer segments are in use, and a command requiring a new
segment is received
•
When the Eject switch is pressed
•
When the SYNCHRONIZE CACHE command is received