Purpose of battery in perc5/i controller

[Sander Steffann]

Hi Radim,
  But, IMHO, it will work correctly only when your harddrive write cache is disabled, which will slow down the disks.
  (there is up to 32MB of HDD's cache and when power goes down, cached data will be lost)

  Correct me if  i'm wrong
The controller can only remove write-information from its cache when the harddisk has committed the data to 'safe' storage. If the disk lies to the controller (by using a write-back cache) then yes, this will not be reliable. Everything has to work together to keep it reliable. Maybe we need disks with their own batteries for their cache...

- Sander
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