Areca 24/4 Internal/External Port Pcie 3.0 12 Gb/s SAS/SATA Raid Controller 2Gb Cache - Manual (Page 188)

WEB BROWSER-BASED CONFIGURATION
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quently, this can prevent a pause in data flow and there will
be continues data access and stream. This feature is very use
ful 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 sub
system. 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.
• Read Ahead Count
The Read Ahead count is used to define how many times (1, 2,
3, ….., 10) of the “Amount of Read Ahead X Read Ahead Re-
quests“ data reading at a time. Default value is Auto: Controller
will base on the HDD number to set the amount of Read Ahead
Count value. You can select between Auto, 1, 2, ….. or 10.
• Read Ahead Requests
The Read Ahead Requests is used to define how many times (1,
2, 3) of the “Amount of Read Ahead “ data reading at a time.
Default value is 1. You can select between 1, 2, or 3.
• 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 transfer-
ring stream data efficiently on an existing RAID controller.