problems with AHCI on FreeBSD 8.2

[Tom Evans]

On Tue, Feb 14, 2012 at 7:52 PM, Jeremy Chadwick
<freebsd at jdc.parodius.com> wrote:
> On Tue, Feb 14, 2012 at 08:31:23PM +0100, Oscar Prieto wrote:
>> I used to had tons of ahci errors in my 4 disk raidz1 worth of
>> HD154UIs when the rig was built a year ago or so (with 8.0 Release),
>> but they dissapeared after tuning ZFS.
>>
>> Sadly i also got a new timeout days ago followed with smartcl erros i
>> still keep unchecked but i guess they cold be legit, i still have to
>> test/swap cables and give it a try.

Interesting. I have 9 SAMSUNG HD154UI 1AG01118 in my raidz setup,
haven't had a problem with any of them yet (touch wood).

> Further details which pertain to Samsung drives:
>
> In your case, you run smartd(8), which periodically hits the drive with
> SMART requests, pulling attribute data down and parsing it.  I believe
> your model is fine for this, but for similar Samsung models, I must
> strongly advise against this.  There are well-documented problems with
> Samsung firmwares and SMART behaviour which can result in data loss (yes
> you read that right).  Please see smartmontools' Wiki page on the matter
> for full details.  Just make sure you're running a fixed firmware:
>
> http://sourceforge.net/apps/trac/smartmontools/wiki/SamsungF4EGBadBlocks
>

Yikes, I have just this week installed a HD204UI. From that page,
drives manufactured after December 2010 should not be affected, which
is fortunate as the linked firmware page doesn't seem to exist
anymore, Samsung no longer seem to offer support for their drives and
point you at Seagate, whose site (of course!) only has downloads for
current Seagate drives.


Hmm reading later on in the thread there is a patch to mark certain
drives as having flaky NCQ - in the patch it is for the SAMSUNG
HD154UI. As I mentioned before, I have 9 SAMSUNG HD154UI, all of which
use ahci(4) and NCQ, and all work perfectly, no timeouts. This is
using 9-STABLE.

I suspect that there may be more going on than 'flaky NCQ', and that
perhaps disabling NCQ masks the real issue.

Cheers

Tom