1.2NVRAM and Flash ROM

A 32 KB x 8 NVRAM stores RAID system configuration information. The MegaRAID SCSI 320-2 firmware is stored in flash ROM for easy upgrade.

1.3SCSI Connectors

The MegaRAID SCSI 320-2 has two ultra high-density 68-pin external SCSI connectors and two 68-pin internal SCSI connectors for internal SCSI drives.

1.4Single-Ended and Differential SCSI Buses

The SCSI standard defines two electrical buses:

•Single-ended bus

•Low-voltage differential bus

1.5Maximum Cable Length for SCSI Standards

Table 1.1 lists the maximum SCSI cable length and number of disk drives that you can use, depending on the SCSI speeds and type of device.

Table 1.1

Maximum Cable Length for SCSI Standards

 

 

 

 

 

 

 

Single Ended

Low-Voltage

Maximum # of

Standard

 

SCSI

Differential SCSI

Drives

 

 

 

 

 

Ultra SCSI

 

1.5 m

12 m

7

 

 

 

 

 

Ultra SCSI

 

3 m

12 m

3

 

 

 

 

Wide Ultra SCSI

 

12 m

15

 

 

 

 

Wide Ultra SCSI

1.5 m

12 m

7

 

 

 

 

Wide Ultra SCSI

3 m

12 m

3

 

 

 

 

 

1-2Overview

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