db1046 has a faulty BBU:
Auto learn is disabled
root@db1046:~# megacli -AdpBbuCmd -a0 | grep Auto-Learn Auto-Learn Mode: Warn via Event
And it looks degraded:
root@db1046:~# megacli -AdpBbuCmd -a0 BBU status for Adapter: 0 BatteryType: BBU Voltage: 4018 mV Current: 0 mA Temperature: 37 C Battery State: Degraded(Need Attention) A manual learn is required. BBU Firmware Status: Charging Status : None Voltage : OK Temperature : OK Learn Cycle Requested : Yes 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 : Yes 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 : No Discharging : Yes Initialized : Yes Remaining Time Alarm : No Discharge Terminated : No Over Temperature : No Charging Terminated : No Over Charged : No Relative State of Charge: 9 % Charger Status: Complete Remaining Capacity: 18 mAh Full Charge Capacity: 194 mAh isSOHGood: Yes Battery backup charge time : 0 hours BBU Capacity Info for Adapter: 0 Relative State of Charge: 9 % Absolute State of charge: 1 % Remaining Capacity: 18 mAh Full Charge Capacity: 194 mAh Run time to empty: Battery is not being charged. Average time to empty: Battery is not being charged. Estimated Time to full recharge: Battery is not being charged. Cycle Count: 32 Max Error = 0 % Remaining Capacity Alarm = 170 mAh Remining Time Alarm = 10 Min BBU Design Info for Adapter: 0 Date of Manufacture: 11/17, 2010 Design Capacity: 1700 mAh Design Voltage: 3700 mV Specification Info: 33 Serial Number: 5154 Pack Stat Configuration: 0x0000 Manufacture Name: SANYO Firmware Version : Device Name: DLNU209 Device Chemistry: LION Battery FRU: N/A Transparent Learn = 0 App Data = 0 BBU Properties for Adapter: 0 Auto Learn Period: 90 Days Next Learn time: None Learn Delay Interval:0 Hours Auto-Learn Mode: Warn via Event
Because of that the RAID policy went to WriteThrough (which can affect performance):
Auto-Learn Mode: Warn via Event root@db1046:~# megacli -LDInfo -Lall -aALL Adapter 0 -- Virtual Drive Information: Virtual Drive: 0 (Target Id: 0) Name : RAID Level : Primary-1, Secondary-0, RAID Level Qualifier-0 Size : 1.633 TB Sector Size : 512 Mirror Data : 1.633 TB State : Optimal Strip Size : 256 KB Number Of Drives per span:2 Span Depth : 6 Default Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAdaptive, Direct, No Write Cache if Bad BBU
In some other cases we have seen that a manual relearn cycle fixes the issue (although temporarily as it comes back after a few hours/days/weeks) (see: T160731#3109104)
So I forced a relearn:
root@db1046:~# megacli -AdpBbuCmd -BbuLearn -aALL -NoLog Adapter 0: BBU Learn Succeeded. Exit Code: 0x00
It is now recharging the battery slowly, but it is still degraded:
Relative State of Charge: 19 % Absolute State of charge: 2 %
We can always force the policy to go back to WriteBack if we see performance issues. The command would be:
megacli -LDSetProp -ForcedWB -Immediate -Lall -aAll
I have not executed it as I would like @Ottomata and/or @elukey to review it (forcing the policy to WB is something we have done before and should not cause issues per se see: T166108)
Probably this issue has been like this for a long time and if we have not seen any performance issues, it is of course safer to leave it to WriteThrough