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Date:      Tue, 11 Mar 2014 17:09:23 +0100
From:      Willem Jan Withagen <wjw@digiware.nl>
To:        "Pokala, Ravi" <rpokala@panasas.com>,  "hardware@freebsd.org" <hardware@freebsd.org>
Subject:   Re: Differences between disk controllers
Message-ID:  <531F3533.7000407@digiware.nl>
In-Reply-To: <CF4474B3.108A9A%rpokala@panasas.com>
References:  <CF4474B3.108A9A%rpokala@panasas.com>

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On 11-3-2014 16:34, Pokala, Ravi wrote:
> 
> 
>> Date: Mon, 10 Mar 2014 22:52:16 +0100
>> From: Willem Jan Withagen <wjw@digiware.nl>
>> To: hardware@freebsd.org
>> Subject: Differences between disk controllers
>> Message-ID: <531E3410.5090602@digiware.nl>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Hi,
>>
>> Running:
>> 	FreeBSD 10.0-STABLE #0 r262730
>>
>> I've build a ZFS system, with 4 disks on a regular Marvell controller,
>> and 4 disks on an Areca controller. Disk are 4T WD REDs.
>>
>> I noticed that there were some discrepancies when I build a raidz of 4
>> "marvell" disks when compared to a raidz on the Areca controller.
>>
>> The essential difference is that on the basic controller the disks are
>> recognised as being 4K disks with quirks. On the Areca controller there
>> is no quirk that matches...
>>
>> Is this a typical problem on the Areca controller? Or does this not work?
> 
> The Marvell controller is recognized as a SATA controller, so the drives
> attached to it are treated as SATA drives, using the ATACAM stack:
> 
>     ada0: <WDC WD40EFRX-68WT0N0 80.00A80> ATA-9 SATA 3.x device
> 
> 
> The drive in question is listed along with the SATA quirks:
> 
> 
>     sys/cam/ata/ata_da.c :: ada_quirk_table[]
>         {
>                 /* WDC Caviar Green Advanced Format (4k) drives */
>                 { T_DIRECT, SIP_MEDIA_FIXED, "*", "WDC WD????RX*", "*" },
>                 /*quirks*/ADA_Q_4K
>         },
> 
> 
> The Areca controller appears to be acting as a *SAS* controller, so the
> drives attached to it are treated as SAS drives, using the SCSICAM stack:
> 
>     da0: <WDC WD40EFRX-68WT0N0 R001> Fixed Direct Access SCSI-5 device
> 
> While the SCSICAM stack knows about quirks for SCSI/SAS drives, it doesn't
> know anything about quirks for SATA drives.
> 
> There may be an argument there to create a unified quirk list, but that's
> a larger discussion.

That is probably is correct summation of my question...
I more or less expected things not to be different in such extend.

--WjW




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