Date: Tue, 6 Jan 2015 14:39:49 -0500
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Jeff Layton <jlayton@primarydata.com>, linux-nfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: [PATCH 14/18] nfsd: pNFS block layout driver
Message-ID: <20150106193949.GD28003@fieldses.org>
References: <1420561721-9150-1-git-send-email-hch@lst.de>
 <1420561721-9150-15-git-send-email-hch@lst.de>
 <20150106171658.GD12067@fieldses.org>
 <20150106173957.GA16200@lst.de>
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In-Reply-To: <20150106173957.GA16200@lst.de>
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On Tue, Jan 06, 2015 at 06:39:57PM +0100, Christoph Hellwig wrote:
> On Tue, Jan 06, 2015 at 12:16:58PM -0500, J. Bruce Fields wrote:
> > > +file system must sit on shared storage (typically iSCSI) that is accessible
> > > +to the clients as well as the server.  The file system needs to either sit
> > > +directly on the exported volume, or on a RAID 0 using the MD software RAID
> > > +driver with the version 1 superblock format.  If the filesystem uses sits
> > > +on a RAID 0 device the clients will automatically stripe their I/O over
> > > +multiple LUNs.
> > > +
> > > +On the server pNFS block volume support is automatically if the file system
> > 
> > s/automatically/automatically enabled/.
> > 
> > So there's no server-side configuration required at all?
> 
> The only required configuration is the fencing helper script if you
> want to be able to fence a non-responding client.  For simple test setups
> everything will just work out of the box.

I think we want at a minimum some kind of server-side "off" switch.

If nothing else it'd be handy for troubleshooting.  ("Server crashing?
Could you turn off pnfs blocks and try again?")

--b.