Return-Path: linux-nfs-owner@vger.kernel.org Received: from pfw.demon.co.uk ([62.49.22.168]:47944 "EHLO pfw.demon.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755757Ab3HFPib (ORCPT ); Tue, 6 Aug 2013 11:38:31 -0400 Date: Tue, 6 Aug 2013 15:38:27 +0000 From: Larry Keegan To: "J. Bruce Fields" Cc: Jeff Layton , Subject: Re: nfs client: Now you see it, now you don't (aka spurious ESTALE errors) Message-ID: <20130806153827.19a1ec21@cs3.al.itld> In-Reply-To: <20130806133407.GB5282@fieldses.org> References: <20130725134515.67af44e2@cs3.al.itld> <20130725101143.6a22cb81@corrin.poochiereds.net> <20130725170526.6e54c7db@cs3.al.itld> <20130726145937.GB30651@fieldses.org> <20130726232111.2567a941@cs3.al.itld> <20130806110209.56e554a7@cs3.al.itld> <20130806071428.5d68052a@corrin.poochiereds.net> <20130806133407.GB5282@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, 6 Aug 2013 09:34:07 -0400 "J. Bruce Fields" wrote: > On Tue, Aug 06, 2013 at 07:14:28AM -0400, Jeff Layton wrote: > > On Tue, 6 Aug 2013 11:02:09 +0000 > > Larry Keegan wrote: > > > These figures seem reasonable for a single SATA HDD in concert > > > with dmcrypt. Whilst I expected some degradation from exporting > > > and mounting sync, I have to say that I'm truly flabbergasted by > > > the difference between the sync and async figures. I can't help > > > but think I am still suffering from some sort of configuration > > > problem. Do the numbers from the NFS client seem unreasonable? > > > > > > > That's expected. Performance is the tradeoff for tight cache > > coherency. > > > > With -o sync, each write() sycall requires a round trip to the > > server. They don't get batched and you can't issue them in > > parallel. That has a terrible effect on write performance. > > Note also mounting -osync and exporting with the "sync" export option > are entirely different things. > > The defaults are what you want (async mount option, sync export > option) unless you've thought hard about it. This is especially true > on the server, since the "async" export option make it skip > committing data to disk even when the protocol mandates it. Righto. This makes sense. After a brief pause I'll see if I can tickle the ESTALE problem under NFS 4. With many thanks. Yours, Larry.