4.9.2Cache Memory

MegaRAID SCSI 320-0 supports 32 to 128 Mbytes of ECC SDRAM DIMM on-board cache memory. MegaRAID supports write-through or write-back caching, which can be selected for each logical drive. To improve performance in sequential disk accesses, MegaRAID does not use read-ahead caching for the current logical drive. The default setting for the read policy is Normal, meaning no read-ahead caching. You can disable read-ahead caching.

Warning: Write caching is not recommended for the physical drives. When write cache is enabled, loss of data can occur when power is interrupted.

4.9.3MegaRAID BIOS

The BIOS resides on a 1 Mbyte × 8 flash ROM for easy upgrade. The MegaRAID BIOS supports INT 13h calls to boot DOS without special software or device drivers. The MegaRAID BIOS provides an extensive setup utility that can be accessed by pressing <Ctrl><M> at BIOS initialization. The MegaRAID BIOS Configuration Utility is described in the MegaRAID Configuration Software Guide.

4.9.4SCSI Firmware

The MegaRAID SCSI 320-0 firmware handles all RAID and SCSI command processing and also supports the items in Table 4.7.

Table 4.7

SCSI Firmware

 

 

 

Feature

 

Description

 

 

 

Disconnect/

 

Optimizes SCSI bus seek.

reconnect

 

 

 

 

 

Stripe size

 

Variable for all logical drives: 2, 4, 8, 16, 32, 64, or 128

 

 

Kbytes.

 

 

 

Rebuild

 

Multiple rebuilds and consistency checks with user-

 

 

definable priority.

 

 

 

MegaRAID SCSI 320-0 Specifications

4-7

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