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Normally you should not need to modify this value. There are two selections, either 2 retry or 3
retry.
Buffer Threshold
•
This new feature there are 3 options; 25%, 50%, 75%. The percentage represents how much
data should be kept in resident cache memory (how full cache should get) before controller
starts to flush data onto the hard drives. If the buffer is set for 25%, then all 25% will be cached
and is used for writing data. The remaining cache memory will be used for reading and
other system overhead. Write buffer threshold for 5% is added for video recording. This
option will push data to disk early.
This feature gives controller extra buffer time in case of slow response from the hard drives
within a given time. Consequently, this can prevent a pause in data flow and there will be
continues data access and stream. This feature is very useful for the video streaming
applications where there is high demand for constant non-stop data flow with no interruption
due to lower performance of specific hardware.
Amount of Read Ahead
•
Read-Ahead data is buffered in the RAID controller cache, however, thereby cutting down on
the amount of I/O traffic to the disk. The Amount of Read Ahead defines how many data of
reading at a time, making more efficient use of the RAID subsystem. This makes it possible to
locate and re-issue the data without repetitive hard parsing activities. The Amount of Read
Ahead parameter is used to allocate an amount of memory in the cache memory the frequently
executed queries and return the result set back to the host without real disk read execution.
Default value is Auto: Controller will base on the HDD number to set the amount of Read Ahead
value. You can select between 512KB ~ 16MB.
Number of AV Stream
•
RAID controllers are required to have not only the function of processing ordinary data but also
the function of dealing with AV (audio/video) stream data needing real-time processing.
Since the bus cycle used in RAID controller was designed to transfer the computer data exactly,
it was unsuitable for the transfer of AV stream needing great band widths. They are required to
do some setting for the handshaking during the processing of stream data. This setting is an
object of transferring stream data efficiently on an existing RAID controller. Normally you should
not need to modify this value. Default value is 6. You can select between 6~256.
To decide how to set AV stream playout parameter, you need to check the Number of Stream,
Amount of Read Ahead, and Total Cache Memory during runtime. You can try to adjust the
three numbers to get the best performance as your requirement. Number of Stream shows the
number of stream added to the system, Amount of Read Ahead shows the amount of Read
Ahead data taken from the cache without real disk execution, and total cache memory shows
the total available memory being installed in the RAID controller.
Optimize AV Recording
•
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