Avago Technologies eXtremeRAID 3000 - Manual (Page 48)

BDIMM Operation
A-2 eXtremeRAID 3000 Installation Guide
BDIMM Operation
This BDIMM consists of 32MB, 64MB, 128MB of ECC
1
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