# FreeBSD 8.2 AHCI and hardware raid (Nvidia)



## mantic (Mar 21, 2011)

Hi,

I have ar0 set up from 2 disks doing raid0. I'm assuming this doesn't give native mode.


```
atapci1: <nVidia nForce MCP55 SATA300 controller>

ar0: 953880MB <nVidia MediaShield RAID0 (stripe 64 KB)> status: READY
```

When I try to enable AHCI for NCQ the ar0 raid group drops out and all the disks are labelled ad0a0 - 1

Is there any way to enable NCQ on the MCP55 driver?

mantic


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## mantic (Mar 21, 2011)

Blah, I'm guessing I'll just have to run software raid in ZFS or something...


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## SirDice (Mar 21, 2011)

You can use either ahci(4) or ataraid(4), not both.


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## User23 (Mar 24, 2011)

The MCP55 does not support AHCI. And be warned of using the "nVidia MediaShield" fakeraid because the ataraid driver can only read the metadata and not write it. It is safer and much more compatible to use gmirror.


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## mav@ (Mar 24, 2011)

NVIDIA supports AHCI standard only from MCP65. Earlier chips had own undocumented mechanisms for supporting NCQ, not implemented for FreeBSD.

What's about ataraid(4), I am now in a process of committing to FreeBSD 9-CURRENT newer replacement for it -- graid. Among the others it includes support for NVIDIA MediaShield, and it can be used with any disk driver, including ahci(4) and other CAM-based drivers. With some luck we may see it in 8-STABLE in few weeks.


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