MSG RAID battery troubleshooting

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MSG is reporting the following alerts:
Appliance RAID is in Write-Through mode, performance will be degraded
Appliance Hardware Alert - Battery ROMB Battery | Low | Asserted


Battery relearn

Battery relearns occur every 90 days by Hardware default. During a battery relearn, the battery fully discharges and gains statistical information regarding its overall State of Health (SoH). When the battery charge drops below a charge threshold, the disk write-cache policy changes to Write-Through.

What does disk Write-Through mean? This means that the data writes occur twice (to Memory and Disk) to protect and preserve the data in the event of a critical hardware failure or disk failure.

The battery will fully discharge, and when the disk write-cache policy changes to Write-Through, the Appliance RAID is degraded and performance is affected. Any changes to hardware or something that will trigger an asserted failure (such as ROMB Battery failed (since it's discharged entirely)), will generate a PPS alert.

As the battery recharges, the disk write-cache policy changes to Write-back. As this is the normal state of the hardware, the alerts will cease as the battery is operational and the SoH is good.

As this happens every 90 days for each appliance where a RAID Controller is present, you should expect to see these alerts reoccur regularly. If the appliance doesn't recover (can be expected to happen in a few hours), open a support ticket.


Article no: 000008712