Asus DS300f, User Manual

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Chapter 9: Technology Background
Read Cache Policy
•
Read Cache
– The read cache is enabled.
•
Read Ahead
– The read cache and the read-ahead feature are enabled.
Read-ahead anticipates the next read and performs it before the request is
made. Can increase read performance.
•
Forced Read Ahead
– The read cache and aggressive pre-fetch feature are
enabled
. See ―Forced Read-Ahead Cache‖ below.
•
No Cache
– The read cache is disabled.
Write Cache Policy
•
Write Back
– Data is written first to the cache, then to the logical drive.
Better performance. ASUS Storage has a cache backup battery to protect
data in the cache from a sudden power failure.
•
Write Thru
– Also ―Write Through‖. Data is written to the cache and the
logical drive at the same time. Safer.
If your write cache policy is set to Write Back , the write policy automatically
changes to Write Thru when all of the following conditions occur:
•
The logical drive write policy is set to Write Back
•
The Adaptive Writeback Cache feature is enabled
•
The cache backup battery goes offline
When the battery comes back online, the write policy automatically changes back
to Write Back.
Forced Read-Ahead Cache
On the ASUS Storage subsystem, you can set the logical drive read cache policy
to Forced Read Ahead an enable the aggressive pre-fetch feature.
The Forced Read-Ahead cache policy setting provides predictive pre-fetching of
data requests, allowing the controller to aggressively buffer large chunks of data
in cache memory to prevent frame drops on high-bandwidth video playback. Not
normally enabled for non-video applications.
Adaptive Writeback Cache
On the ASUS Storage subsystem, you can set the logical drive write cache policy
to
Write Thru or Write Back .
If you set the write cache policy to Write Back , your data is first written to the
controller cache, and later to the logical drive. This action improves performance.
To preserve the data in the cache in the event of a power failure, the subsystem
has a backup battery that powers the cache. To see an estimate of how long the