Exalogic Battery Check and Replacement Guidelines

Asset ID:	1-71-1437353.1
Update Date:	2012-07-20
Keywords:

Solution Type Technical Instruction Sure

Solution 1437353.1 : Exalogic Battery Check and Replacement Guidelines

Applies to:

Oracle Exalogic Elastic Cloud X2-2 Hardware - Version Not Applicable to Not Applicable [Release N/A]
Oracle Exalogic Elastic Cloud X2-2 Full Rack - Version Not Applicable to Not Applicable [Release N/A]
Oracle Exalogic Elastic Cloud X2-2 Half Rack - Version Not Applicable to Not Applicable [Release N/A]
Oracle Exalogic Elastic Cloud X2-2 Qtr Rack - Version Not Applicable to Not Applicable [Release N/A]
Oracle Exalogic Elastic Cloud X2-2 One-Eighth Rack - Version Not Applicable to Not Applicable [Release N/A]
Information in this document applies to any platform.
Exalogic Battery Check and Replacement Guidelines

Goal

In an Exalogic Machine, the LSI RAID controllers contain a battery backup unit (BBU) to hold power to the controller cache in the event of mains failure. The design targets a maximum holdover of 48 hours to guarantee no loss of data which is in cache and not yet written to disk.
When the BBU falls below capacity, or is going through a periodic learn cycle (scheduled discharge &recharge), the controller switches to "Write Through mode" so the operating system waits for confirmation that data has been written to disk rather than only delivered to the cache.
When the battery goes into a learn cycle, it will drain completely, then recharge. It will also throw an error indicating the learn cycle.

This results in a reduction in performance but removes the risk that data could be lost in a power fail situation while data is in cache. The absolute minimum charge capacity on a BBU08 battery backup unit required to meet the minimum 48 hours hold-up time is 674mAh.
If it goes below this value, the BBU can no longer support the cache for the duration required and needs replacement immediately.

Besides charge capacity, another parameter that needs to be checked is Max Error. Max Error is a reading that determines whether the reading of the battery condition is accurate or not. An error limit of <10% is considered to be a valid condition reading. If it is greater, then the BBU should be treated as failed.

The following commands should be used to gather the information for troubleshooting:

1) For complete battery backup information run the following command.

/opt/MegaRAID/MegaCli/MegaCli64 -adpbbucmd -aALL

2) This command is used to check battery capacity specifically:-

/opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -a0 | grep "Capacity"

Remaining Capacity: 597 mAh

Full Charge Capacity: 612 mAh

Design Capacity: 1215 mAh

3) This command is used to segregate the Full Charge Capacity value and Max Error

# /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -a0 | grep "Full Charge" -A5 | sort | grep Full -A1

Full Charge Capacity: 1357 mAh

Max Error: 2 %

#

Based on the results from the above commands, The two parameters that we need to check to determine a good battery are:

1) Full Charge Capacity: a good battery should show greater than 800 mAh
2) Max Error: "Max Error" should be <10%

Fix

Guidelines :

- Check the battery status and replace battery if the full charge capacity after learn cycle is less than 674 mAh, regardless of any other BBU output field.

- if the full charge capacity after learn cycle is less than 800 mAh. Run a new learn cycle and confirm the battery condition again. Replace battery within the next 60 days if it is still showing less than 800 mAh.

- Check the battery status and replace battery if the Max Error rate reported is greater than 10%.

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