Oracle-Ninja.com Andy Colvin's Oracle Blog

Exadata V2 Battery Replacement

For some reason, I've been working on lots of Exadata V2 systems in the past few months.  One of the issues that I've been coming across for these clients is a failure in the battery that is used by the RAID controller.  It was originally expected for these batteries to last 2 years.  Unfortunately, there is a defect in the batteries where they reach their end of life after approximately 18 months.  The local Sun reps should have access to a schedule that says when the "regular maintenance" should occur.  For one client, it wasn't caught until the batteries had run down completely and the disks were in WriteThrough mode.  This can be seen by running MegaCLI64.  Here is the output to check the WriteBack/WriteThrough status for 2 different compute nodes (V2 is first, X2-2 is second):

[enkdb01:root] /root
> dmidecode -s system-product-name
SUN FIRE X4170 SERVER          
 
[enkdb01:root] /root
> /opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -LALL -aALL | grep "Cache Policy"
Default Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU
Disk Cache Policy   : Disabled

[root@enkdb03 ~]# dmidecode -s system-product-name
SUN FIRE X4170 M2 SERVER
[root@enkdb03 ~]# /opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -LALL -aALL | grep "Cache Policy"
Default Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU
Current Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU
Disk Cache Policy   : Disabled

If you have a V2 and you haven't replaced the batteries yet, it's worth running these commands to see what state your RAID controllers are in.  To find out what this means for you, read on after the break.