Return-Path: Received: from rcsinet10.oracle.com ([148.87.113.121]:24454 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754327Ab0HKQGl convert rfc822-to-8bit (ORCPT ); Wed, 11 Aug 2010 12:06:41 -0400 Subject: Re: Tuning NFS client write pagecache Content-Type: text/plain; charset=us-ascii From: Chuck Lever In-Reply-To: Date: Wed, 11 Aug 2010 10:05:32 -0600 Cc: "linux-nfs@vger.kernel.org Mailing list" Message-Id: <1EDC250A-9F5E-4353-A78D-0A16B2612BBD@oracle.com> References: <4C5BFE47.8020905@mxtelecom.com> <20100806132620.GA2921@merit.edu> <1281116260.2900.6.camel@heimdal.trondhjem.org> <1281123565.2900.17.camel@heimdal.trondhjem.org> <98DC3FB9-72A7-44CF-AB8B-914F2379B01B@oracle.com> <0A97A441BFADC74EA1E299A79C69DF9213F109F3B2@orsmsx504.amr.corp.intel.com> <3DFB27D5-7AFE-4D03-AB35-9BCCBD5C6CA6@oracle.com> To: Peter Chacko Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 [ Trimming CC: list ] On Aug 10, 2010, at 8:09 PM, Peter Chacko wrote: > Chuck, > > Ok i will then check to see the command line option to request the DIO > mode for NFS, as you suggested. > > yes i other wise I fully understand the need of client caching.....for > desktop bound or any general purpose applications... AFS, cacheFS are > all good products in its own right.....but the only problem in such > cases are cache coherence issues...(i mean other application clientss > are not guaranteed to get the latest data,on their read) ..as NFS > honor only open-to-close session semantics. > > The situation i have is that, > > we have a data protection product, that has agents on indvidual > servers and a storage gateway.(which is an NFS mounted box). The only > purpose of this box is to store all data, in a streaming write > mode.....for all the data coming from 10s of agents....essentially > this acts like a VTL target....from this node, to NFS server node, > there is no data travelling in the reverse path (or from the client > cache to the application). > > THis is the only use we put NFS under.... > > For recovery, its again a streamed read...... we never updating the > read data, or re-reading the updated data....This is special , single > function box..... > > What do you think the best mount options for this scenario ? What is the data rate (both IOPS and data throughput) of both the read and write cases? How large are application read and write ops, on average? What kind of networking is deployed? What is the server and clients (hardware and OS)? And, I assume you are asking because the environment is not performing as you expect. Can you detail your performance issues? -- Chuck Lever chuck[dot]lever[at]oracle[dot]com