Date: Thu, 1 Dec 2005 15:47:45 +0100
From: Heinz Mauelshagen <mauelshagen@redhat.com>
To: "Salyzyn, Mark" <mark_salyzyn@adaptec.com>
Cc: Christoph Hellwig <hch@infradead.org>,
       "Darrick J. Wong" <djwong@us.ibm.com>, Chris McDermott <lcm@us.ibm.com>,
       Luvella McFadden <luvella@us.ibm.com>, AJ Johnson <blujuice@us.ibm.com>,
       Kevin Stansell <kstansel@us.ibm.com>, linux-kernel@vger.kernel.org,
       linux-scsi@vger.kernel.org, Mauelshagen@redhat.com
Subject: Re: [PATCH] aic79xx should be able to ignore HostRAID enabled adapters
Message-ID: <20051201144745.GI2782@redhat.com>
Reply-To: mauelshagen@redhat.com
References: <547AF3BD0F3F0B4CBDC379BAC7E4189F01E3E318@otce2k03.adaptec.com>
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On Thu, Dec 01, 2005 at 08:44:15AM -0500, Salyzyn, Mark wrote:
> Christoph Hellwig sez:
> > NACK.  We're not going to support attaching broken propritary drivers.
> 
> Understood and expected.
> 
> The word 'broken' is hardly chosen for scientific reasons, bespeaks an
> agenda ;-> Just because you can not see the code, does not mean it is
> broken.
> 
> I have on numerous attempts tried to contact Heinz Mauelshagen to
> fortify dmraid in support of the HostRAID adapters. He has yet to
> respond to my emails to start a dialogue with Adaptec.

None of those here.
Please forward.

> 
> Justin Gibbs had provided the community the emd driver, soundly rejected
> and never ported to dm because there were features that Justin held dear
> in md that do not translate to dm. An unfortunate waste of considerable
> resources.
> 
> Without the timely agenda and cooled temperaments to close the gap, the
> solution should be temporarily to support the proprietary HostRAID
> driver when the Adapter is in HostRAID mode and we continue to work to
> close that gap on dmraid.
> 
> Could you agree with that to help the users today?
> 
> [ You are on record as not giving a fig for the users, what if I showed
> them as starving children in a third world nation, would that melt your
> heart? ;-} ]
> 
> > Sepcially as these "HostRAID" cards are plain SCSI HBAs.
> 
> They are plain SCSI HBAs, but are designated as a RAID card rather than
> a Host Bus Adapter in the PCI config space when in 'HostRAID' mode. The
> fact that is designated in the PCI space should be enough reason *not*
> to attach a simplified LLD.
> 
> The HostRAID driver has a specialized (ok, yes, also proprietary) CHIM
> and sequencer where attention can be focused on techniques of
> performance improvement and OS agnostics. In addition, the RAID code in
> that driver understands the hardware, CHIM & sequencer and takes
> advantage of features that just can not be performed by an abstracted dm
> or an LLD. RAID1 is handled under some conditions, for instance, with
> one DMA operation over the PCI bus rather than two duplicated for each
> target, greatly increasing the performance.
> 
> Linux is not about performance first, it is about doing it the Linux
> way. I believe we can understand that. And in turn, do not consider it
> harmful if a group of individuals trying to make a living see a chance
> to acquire a competitive edge.
> 
> Sincerely -- Mark Salyzyn

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
Cluster and Storage Development                   56242 Marienrachdorf
                                                  Germany
Mauelshagen@RedHat.com                            +49 2626 141200
                                                       FAX 924446
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