Purpose of battery in perc5/i controller

[Tino Schwarze]

On Sat, Mar 01, 2008 at 03:00:06AM -0500, Dmitriy Beloslyudtsev wrote:
> What is the purpose of battery in perc5/i scsi raid controller? Let's
> imagine we have a write cache in write-back mode and during disk write
> operation we lost the power. If the battery is needed to flush the cache
> content to the physical disks during this power outage, who will produce the
> power to spin the physical disks in internal bays of pe2950? Am I missing
> some key concept in here?

The battery will only buffer the controller's RAM. So next time the
system boots up, the controller will remember that there's still
something to write to disk and it will do so.

HTH,

Tino.

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