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Date:      Tue, 23 Feb 2010 18:18:55 +0200
From:      Alexander Motin <mav@FreeBSD.org>
To:        Harald Schmalzbauer <h.schmalzbauer@omnilan.de>
Cc:        freebsd-stable@FreeBSD.org
Subject:   Re: ahcich timeouts, only with ahci, not with ataahci
Message-ID:  <4B83FFEF.7010509@FreeBSD.org>
In-Reply-To: <4B83FD62.2020407@omnilan.de>
References:  <1266934981.00222684.1266922202@10.7.7.3> <4B83EFD4.8050403@FreeBSD.org> <4B83FD62.2020407@omnilan.de>

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Harald Schmalzbauer wrote:
> Maybe it's helpful to you. Since I haven't seen the hang after
> upgrading, although doing extensive network transfer tests, I thought it
> vanished and haven't kept logs safe...

Enabling verbose kernel messages may give a bit more info.

>>> Kernel is from Feb. 19, so recent ahci improovements are active.
>>> Controller is ICH9R with 3 Samsung F3 SpinPoints.
>>>
>>> Any ideas how to work arround the hangs other than using the old ahci
>>> driver?
>>
>> Old ataahci driver wasn't using NCQ. NCQ may trigger some bugs in drive
>> firmware or expose some protocol inconsistencies. I would recommend you
>> to search for some errata for your drive and possibly firmware update.
> 
> Sounds reasonable.
> How can I disable NCQ with new ahci?

There is no user-level control for this yet. It can be done via writing
quirk for this specific device in ata_xpt.c, or via commenting setting
ADA_FLAG_CAN_NCQ flag in ata_da.c, or by adding AHCI_Q_NONCQ quirk for
your controller in ahci.c.

> I guess if it's a HDD firmware issue with NCQ the hang shouldn't happen
> when NCQ is disabled.

Just for case of real I/O timeout, run full surface test with SMART.

> Btw, I found camcontrol cmd ada0 -a "EF 85 00 00 00 00 00 00 00 00 00
> 00" for disabling APM and another one for disabling AAM. I did that for
> my drives. Is there a wiki where we can place such valuable commands?

Probably not. It is just ATA commands, taken from ATA specification, but
definitely it is not very easy way.

-- 
Alexander Motin



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