Disabling BBU Auto Learn with megacli

We are currently facing performance problems with mysql and I remember reading about RAID BBU Learning causing huge write performance drops. So I wanted to check if the RAID controller on our Master database had this configured.

Step#1: Find out what is the brand/model of the RAID controller installed on the server

I can of course ask accounting to pull-up the delivery receipt to find the brand/model but where is the fun in that. Googling led me to the following commands:


sudo lspci | grep -i raid
04:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 2108 [Liberator] (rev 04)

sudo lshw -class storage

description: RAID bus controller

       product: MegaRAID SAS 2108 [Liberator]

       vendor: LSI Logic / Symbios Logic

       physical id: 0

       bus info: pci@0000:04:00.0

       logical name: scsi4

       version: 04

       width: 64 bits

       clock: 33MHz

       capabilities: storage pm pciexpress vpd msi msix bus_master cap_list rom

       configuration: driver=megaraid_sas latency=0

       resources: irq:26 ioport:d800(size=256) memory:fae7c000-fae7ffff memory:faec0000-faefffff memory:fae80000-faebffff

Step#2: Install the megacli package to be able to query the raid card for its status

Downloaded the megacli package from the LSI website. But they only provide RPMs so I had to convert them with:

sudo alien -k MegaCli-8.07.06-1.noarch.rpm

Then installed with:

sudo dpkg -i megacli_8.07.06-1_all.deb

To find out where the files got installed do:

sudo dpkg -c megacli_8.07.06-1_all.deb

Step#3: Use megacli to probe for BBU status and information

Running the command results to something unexpected:

./MegaCli64 -adpCount

Controller Count: 0.

Exit Code: 0x00

megacli cant find the raid adapter. It seems that megacli has an issue with kernels >= 3.0 and can be remedied with:

sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -adpCount

Controller Count: 1.

Exit Code: 0x01

So to find out about the BBU:

sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -GetBbuStatus -aALL

BBU status for Adapter: 0

BatteryType: iBBU

Voltage: 3972 mV

Current: 0 mA

Temperature: 24 C

Battery State: Optimal

BBU Firmware Status:

  Charging Status              : None

  Voltage                                 : OK

  Temperature                             : OK

  Learn Cycle Requested                  : No

  Learn Cycle Active                      : No

  Learn Cycle Status                      : OK

  Learn Cycle Timeout                     : No

  I2c Errors Detected                     : No

  Battery Pack Missing                    : No

  Battery Replacement required            : No

  Remaining Capacity Low                  : No

  Periodic Learn Required                 : No

  Transparent Learn                       : No

  No space to cache offload               : No

  Pack is about to fail & should be replaced : No

  Cache Offload premium feature required  : No

  Module microcode update required        : No

GasGuageStatus:

  Fully Discharged        : No

  Fully Charged           : Yes

  Discharging             : Yes

  Initialized             : Yes

  Remaining Time Alarm    : No

  Discharge Terminated    : No

  Over Temperature        : No

  Charging Terminated     : No

  Over Charged            : No

  Relative State of Charge: 97 %

  Charger System State: 49168

  Charger System Ctrl: 0

  Charging current: 0 mA

  Absolute state of charge: 53 %

  Max Error: 2 %

Exit Code: 0x00

sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -GetBbuCapacityInfo -aALL

BBU Capacity Info for Adapter: 0

  Relative State of Charge: 97 %

  Absolute State of charge: 53 %

  Remaining Capacity: 641 mAh

  Full Charge Capacity: 664 mAh

  Run time to empty: Battery is not being discharged.  

  Average time to empty: Battery is not being discharged.  

  Estimated Time to full recharge: Battery is not being charged.  

  Cycle Count: 37

Max Error = 2 %

Remaining Capacity Alarm = 120 mAh

Remining Time Alarm = 10 Min

Exit Code: 0x00

sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -GetBbuProperties -aALL

BBU Properties for Adapter: 0

  Auto Learn Period: 30 Days

  Next Learn time: Sun Feb 17 19:37:09 2013

  Learn Delay Interval:0 Hours

  Auto-Learn Mode: Enabled

Exit Code: 0x00

Auto learn mode should be disabled and scheduled during off-peak time.

#!/bin/bash

TMPFILE=$(mktemp -p /tmp bbu.relearn.XXXXXXXXXX) || exit 1

echo "autoLearnMode=1" > $TMPFILE

setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -SetBbuProperties -f $TMPFILE -aALL

sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -GetBbuProperties -aALL

rm $TMPFILE

script for safe write back:

#!/bin/bash
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp ADRA -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Cached -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp DisDskCache -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp NoCachedBadBBU -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp WB -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -Lall -aALL


script to force write back without BBU protection:

#!/bin/bash
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp ADRA -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Cached -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp DisDskCache -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp CachedBadBBU -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp WB -Lall -aALL
sudo setarch x86_64 --uname-2.6 /opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -Lall -aALL


Useful Links:
http://linux.dell.com/files/whitepapers/solaris/Managing_PERC6_0714.pdf
http://hwraid.le-vert.net/wiki/LSIMegaRAIDSAS
http://yo61.com/dell-drac-bbu-auto-learn-tests-kill-disk-performance.html


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