Avago Technologies eXtremeRAID 2000 - Manual (Page 42)

BDIMM Operation
A-2 eXtremeRAID 2000 Installation Guide
BDIMM Operation
This BDIMM consists of 32 MB, 64 MB, 128 MB, or 256 MB of Error
Correction Code (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
BBU).
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 Global Array
Manager (GAM). Refer to the RAID EzAssist Configuration Utility User
Reference Guide or 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 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
(Data Retention)” later in this chapter.
Table A-1. Typical Battery Backup Capacity
Memory Size Approximate Battery Charge Life
32 MB 168 hours
64 MB 110 hours
128 MB 60 hours
256 MB 36 hours