Switchover to CAM ATA?
scottl at samsco.org
Tue Apr 27 14:49:35 UTC 2010
On Apr 27, 2010, at 7:34 AM, Dag-Erling Smørgrav wrote:
> Maxim Sobolev <sobomax at FreeBSD.org> writes:
>> Richard Tector <richardtector at thekeelecentre.com> writes:
>>> Could I also add that the removal of ataraid would affect those
>>> users who dual-boot with Windows and rely on the psuedo-raid
>>> provided by most Intel chipsets to be able to share the same pair of
>> Well, this won't be a problem if we have GEOM classes that can
>> understand metadata created by the ATA RAID BIOS(es).
> Most pseudo-raid kit has nifty features like checksum offloading,
> composite writes etc. which can improve performance considerably. You
> can't access those from GEOM.
If my "most" you mean "a small subset of vendors and products", then yes, you're correct. For the vast remaining majority, all you get is a special BIOS that can do striping and mirroring at boot. Sometimes that special BIOS requires a special hook in the controller chip, which is why you have ICHxxR vs ICHxx chips, for example. All the 'R' means is that the silicon supports an external ROM.
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