Policies (see, Read ahead policies – MSI X2-109 v1 User Manual
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MegaRAID BIOS Configuration Utility
Version 2.0
Copyright © 2006 by LSI Logic Corporation. All rights reserved.
4.
Select Yes at the prompt and press Enter.
The CU displays a bar graph showing the initialization progress.
5.
When initialization completes, press Esc to return to the previous 
menu.
If you press Esc while initialization is in progress, the Stop, Continue, 
and Abort options are available, as explained earlier in this section.
3.3
Setting the Hard Disk Write Cache and Read Ahead 
Policies
You can use the MegaRAID BIOS CU to set the hard disk drive Write 
Cache and Read Ahead settings. Any read or write cache policy changes 
apply to all logical drives on an array. In other words, if two logical drives 
are defined on a single array and you change the Read Ahead setting 
on one logical drive, the change will also apply to the other logical drive 
on the array.
The Disk Write Cache and Read Ahead policies can be set to On or Off.
•
When the disk Write Cache is On, a write transaction is considered 
to be complete when all the data has been written to the disk cache. 
When disk Write Cache is Off, the write transaction is complete only 
when the data has been written to the disk.
•
When disk Read Ahead is On, extra data is read sequentially ahead 
of the data that is actually requested and is stored in a cache. If the 
additional read-ahead data is then requested, it can be read faster 
from the cache than from the disk directly.
Note:
When the disk Write Cache is On, there is a danger that 
data could be lost if the power fails before the cached data 
is written to disk.
Follow these steps to view or change the logical drive Write Cache or 
Read Ahead settings:
1.
From the Management Menu, select Objects
→ Logical Drive→
Logical Drive n
→ View/Update Parameters.
2.
Use the arrow key to move the cursor to Disk WC or Read Ahead 
and press Enter.