SUPER MICRO Computer AOC-USAS-L4iR Setting the Hard Disk Write Cache and Read Ahead Policies

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Safety Information and Technical Specifications

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.

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Contents AOC-USAS-L4i AOC-USAS-L4iR Manual Revision 1.0b Release Date October 17 Table of Contents MegaRAID Storage Manager SoftwareOverview and Installation Adding a Saved Storage Configuration Add-on Card Users Guide Overview Product FeaturesOperating Systems Supported An Important Note to UsersHeadquarters Contacting SuperMicroEurope Asia-PacificGeneral Safety Guidelines ESD Safety GuidelinesAn Important Note to Users Add-on Card Users Guide Front Connectors Front Connectors and Jumpers#1. Internal SAS Connector Front Connector and Pin DefinitionsFront Jumper Locations and Pin Definitions Jumper SettingsFront Pane LEDs LED IndicatorsRAID 1 Arrays RAID Minimum Drive RequirementsAdd-on Card Users Guide Performing a Quick Configuration Chapter Driver InstallationConfiguring Arrays and Logic Drives Starting the MegaRAID Bios CUUsing Easy Configuration Logical Drive Configuration Using New Configuration and View/Add ConfigurationSafety Information and Technical Specifications Creating a Global Hotspare Drive Initializing Logical Drives Logical Drive Submenu Setting the Hard Disk Write Cache and Read Ahead Policies Rebuilding a Drive Hot Plug Support Checking Data Consistency Viewing and Changing Device Properties Viewing and Changing Adapter Properties Viewing and Changing Logical Drive Properties Forcing Drives Online or OfflineViewing Physical Drive Properties Deleting a Logical Drive Configuring a Bootable Logical DriveClearing a Storage Configuration Creating Storage Configurations OverviewMonitoring Storage Devices Hardware and Software RequirementsMaintaining Storage Configurations Installation Customer Information Screen Customer Information Screen Installing MegaRAID Storage Manager Software for Linux Linux Error Messages Add-on Card Users Guide Starting MegaRAID Storage Manager Software Chapter MegaRAID Storage Manager Window and MenusSelect Server Window Select Server Window MegaRAID Storage Manager Window Physical/Logical View Panel Event Log Panel Properties/Operations/Graphical View PanelFile Menu Menu BarLog Menu Creating a New Storage Configuration Chapter ConfigurationFirst Screen Configuration Wizard Understanding Virtual Disk Parameters Auto Configuration Screen Using Auto ConfigurationUsing Guided Configuration First Guided Conguration Screen Second Guided Configuration Screen Manual Configuration First Manual Configuration Screen Using Manual Configuration RAIDManual Configuration Defining a Virtual Disk Manual Configuration Adding a Hotspare Safety Information and Technical Specifications Using Manual Configuration RAID Using Manual Configuration RAID Adding Hotspare Disks Changing Adjustable Task Rates Deleting a Virtual Disk Changing Virtual Disk PropertiesClearing a Storage Configuration from a Controller Saving a Storage Configuration to DiskAdding a Saved Storage Configuration