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I just got this message on the front panel of one of our servers, a Dell PowerEdge 2900. I believe this means that the RAID controller card battery is nearly dead. The question that I have is what happens when the battery runs flat? Will the server stop working? Can it cause damage?

Should the server be shut down? need to know as we're nearly at the end of business on a Friday afternoon and it'll be impossible to get a replacement immediately.

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up vote 11 down vote accepted

You may end up with a singularity forming in your server closet if you don't replace it.

Just kidding.

What happens is the PERC controller will stop caching data and your disk performance may drop. That way if there's a power outage, it should prevent you from losing data (or minimize the chances of losing data.

It shouldn't cause any immediate issues if you have to wait a few days to get the new battery. You turn off the server, replace the battery as per the documentation, and power it back up. The server will run fine until you get it replaced.

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Thanks to all who answered. Accepted this one for the singularity – Istari Mar 9 '12 at 13:21

The battery is degrading, though it isn't dead yet.

When it does die, the biggest impact is that the write-cache on your RAID card will be disabled. This will have potentially significant performance impacts, but will not affect stability. You have time to plan for a replacement-outage.

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When the battery dies, it will just turn off the battery backed write cache. This could hurt performance a bit, but shouldn't be a huge deal to run like this in the short term.

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When you change the battery, take note of how the cable is run - it goes through a metal hole. As a consequence of this, if your server ever died, it would be impossible to transfer your RAID card to another server without unplugging the battery. Because of this I normally take the cable out of the metal hole just in case.

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and what the consuguence of unpluggin the battery to transfer the raid to a new server? data loss? – Kreker Nov 12 '15 at 14:50

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