problems with AHCI on FreeBSD 8.2

Harald Schmalzbauer h.schmalzbauer at
Tue Feb 14 17:17:41 UTC 2012

 schrieb Jeremy Chadwick am 14.02.2012 17:50 (localtime):
> On Tue, Feb 14, 2012 at 04:55:10PM +0100, Claudius Herder wrote:
>> Hello,
>> I have got a quite similar problem with AHCI on FreeBSD 8.2 and it still
>> persists on FreeBSD 9.0 release.
>> Switching from ahci to ataahci resolved the problem for me too.
>> I'm using gmirror for swap, system is on a zpool and the problem first
>> occurred during a zpool scrub, but it is easily reproducible with dd.
>> The timeouts only occur when writing to disks, dd if=/dev/ada{0|1}
>> of=/dev/null is not an issue.
>> Sometimes I need to power off the server because after a reboot one disk
>> is still missing.
>> I really would like to help in this issue, so let me know if you need
>> any more information.
> I find it interesting that, at least so far, the only people reporting
> problems of this type with the ahci.ko driver are people using Samsung
> disks.  The only difference is that your models are F1s while the OPs
> are F2s.

I saw such timeouts long ago and mav@ had a look at my postings and he
mentioned it could be a NCQ problem.
I suspected the disks firmware.
I never tracked it down further, because after replacing the Samsung (F3
in that case) disks with hitachi ones solved all my problems and gave a
big performance kick as well (with zfs).
You can find the discussion here:



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