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Message-ID: <4C07E960.2040303@vlnb.net>
Date: Thu, 03 Jun 2010 21:41:52 +0400
From: Vladislav Bolkhovitin <vst@vlnb.net>
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To: Boaz Harrosh <bharrosh@panasas.com>
CC: Christof Schmitt <christof.schmitt@de.ibm.com>, linux-scsi@vger.kernel.org,
       linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
       lsf10-pc@lists.linuxfoundation.org, Nick Piggin <npiggin@suse.de>,
       Al Viro <viro@ZenIV.linux.org.uk>, Chris Mason <chris.mason@oracle.com>,
       James Bottomley <James.Bottomley@HansenPartnership.com>,
       "Martin K. Petersen" <martin.petersen@oracle.com>,
       Ric Wheeler <rwheeler@redhat.com>,
       Matthew Wilcox <willy@linux.intel.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [LFS/VM TOPIC] Stable pages while IO (was Wrong DIF guard tag
 on ext2 write)
References: <20100531112817.GA16260@schmichrtp.mainz.de.ibm.com> <4C07D3D0.8010500@panasas.com>
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Boaz Harrosh, on 06/03/2010 08:09 PM wrote:
> [Topic]
> How to not let pages change while in IO
> 
> [Abstract]
> As seen in a long thread on the fsdvel scsi mailing lists. Lots of
> people have headaches and sleep less nights because individual pages
> can change while in IO and/or DMA. Though each one as slightly different
> needs, the mechanics look to be the same.
> 
> People that care:
> - Mirror and RAID people that need on disk consistency.
> - Network storage that wants data checksum.
> - DIF/DIX people

  - Load balancing MPIO clusters, where out of order execution of 
overlapping write requests for the changed pages can introduce a data 
corruption, which makes using Linux with load balancing MPIO clusters 
unsafe.

> - ...
> 
> I for one know nothing of the subject but am a RAID person and would
> like a solution that does not force me to copy the complete data load.
> 
> Please lets get all the VM VFS and drivers people in one room and see
> if we can have a Linux solution to this problem
> 
> Boaz
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