Mylex eXtremeRAID Installation Guide download pdf (Page 48)

BDIMM Operation

A-2 eXtremeRAID 3000 Installation Guide

BDIMM Operation

This BDIMM consists of 32MB, 64MB, 128MB of ECC

SDRAM cache

memory, a lithium Ion battery, a charging circuit, and power monitoring

circuitry. The controller is shipped with the BDIMM installed or with

standard DIMM memory, without a Battery Backup Module (BBM).

Set-up – Enabling the Write-Back Cache

Maximum RAID performance is achieved when the cache is in write-back

mode. The write-back cache is enabled by toggling the write-back/write-

through mode switch. The write-back/write-through mode switch is accessed

using RAID EzAssist (the BIOS Configuration Utility), or in GAM. Refer to

the RAID EzAssist Configuration Utility User Reference Guide or the Global

Array Manager Client Software Installation Guide and User Manual for

instructions on how to examine and change the mode switch.

Battery Backup Capacity

The battery backup’s capacity varies with the cache memory capacity used.

In the event of a power failure, the battery backup can be expected to

maintain cache data integrity for the periods of time shown in Table A-1. For

more detailed information about battery duration, please see “Battery Charge

Life” later in this chapter.

1. ECC = Error Correction Code

Table A-1. Battery Backup Capacity

Memory Size Approximate Battery Charge Life

32MB 168 hours

64MB 110 hours

128MB 60 hours

256MB 36 hours

1 2 ... 43 44 45 46 47 48 49 50 51 52 53 ... 89 90

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Mylex eXtremeRAID Installation Guide Page 48