HP Smart Array P400/256MB SAS Controller BATTERY

This is probably a dumb question. I recently purchased a couple of refurbished HP SB40C storage blade for our HP Bladesystem c3000 enclosure. Each comes with an HP Smart Array P400/256MB SAS Controller and a 4.8V NI-MH cache raid battery.

The smart array utility warns me about a low charge on the battery for each storage blade. Could it be because they probably haven't been turned on for a while just sitting around in some storage room? I mean of course batteries will drain out on their own, but I'm assuming this is the case rather than a coincidence that both batteries are dead. So just what would most people assume in this case?

Also, how would it affect my array if I use the controller without batteries?

PS: I cant be sure because my enclosure doesn't have enough power supplies (arriving soon) to turn on 4 blades and hence possibly charge the batteries. I have to make a quick decision on whether the order new batteries ASAP or count on their simply needing to recharge.

Thanks!

Solution 1:

You're correct in that the warning is the result of the systems being offline for sometime. Power everything up and they will regain their charge.

In the case that the batteries are dead (unlikely), the impact to array performance is that the array accelerator (write cache) will be disabled. This results in low write performance. There is a mechanism in recent P4xx firmware to override this action, allowing write cache even in the event of a mission or failed battery/flash unit, but it carries consequences of data corruption if you experience total power loss on the blade or blade enclosure.

Solution 2:

The batteries are an item that fails over time. Their purpose is to provide power to the RAID contoller in the event of a power outage, to give enough time to write data that is in the buffer to the platters.