Messages in this thread | | | Date | Wed, 01 Nov 2006 09:37:49 -0500 | From | Mark Lord <> | Subject | Re: AHCI should try to claim all AHCI controllers |
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Alan Cox wrote: > Ar Maw, 2006-10-31 am 21:22 -0800, ysgrifennodd Linus Torvalds: >> (We had the same issue with "PCI IDE controller". Some PCI IDE controllers >> are clearly exactly that from a programming interface standpoint, but >> because they support RAID in hardware, they claim to be RAID controllers, >> since that is more "glamorous". Gaah ;^). > > Actually its far uglier than that. With one exception they don't support > hardware raid mode, they use the RAID class tag to stop other OS drivers > grabbing the interface or seeing it directly as un-raided software raid.
Note that a lot of the software raid controllers actually have full hardware RAID acceleration in the chipset (single block command is automatically remapped across several drives of a RAID 0/1/10 configuration, reducing bus transactions and bandwidth requirements.
But they still require a driver do perform the RAID management, and are thus not true "hardware" RAID. But they are higher on the food chain than total "pretend" RAID devices.
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