From: "J. Bruce Fields" Subject: Re: [NFS] NFS Digest, Vol 18, Issue 70 (NFS performance problems) Date: Mon, 3 Dec 2007 15:31:39 -0500 Message-ID: <20071203203139.GF28201@fieldses.org> References: <47434ED7.4010100@redhat.com> <47435049.1010800@redhat.com> <47445727.5090705@oracle.com> <474A3D6B.2060208@redhat.com> <20071126050230.GD21120@fieldses.org> <18254.19187.470275.538680@notabene.brown> <1196314230.7950.42.camel@heimdal.trondhjem.org> <475039E4.5070903@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: chuck.lever@oracle.com, nfs@lists.sourceforge.net, NeilBrown , Trond Myklebust To: Wendy Cheng Return-path: Received: from neil.brown.name ([220.233.11.133]:51124 "EHLO neil.brown.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818AbXLCUcT (ORCPT ); Mon, 3 Dec 2007 15:32:19 -0500 Received: from brown by neil.brown.name with local (Exim 4.63) (envelope-from ) id 1IzHxh-0007O6-6T for linux-nfs@vger.kernel.org; Tue, 04 Dec 2007 07:32:17 +1100 In-Reply-To: <475039E4.5070903@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Nov 30, 2007 at 11:27:16AM -0500, Wendy Cheng wrote: > Trond Myklebust wrote: >> Actually, the real problem would be dealing with something like >> unlink('foo') followed by open('foo', O_CREAT|O_EXCL). How do you ensure >> that a replay of those actions following a reboot is fully consistent in >> the face of some other client attempting an open('foo', O_CREAT) at the >> same time? >> >> The problem is that a number of directory operations involve exclusive >> semantics, and so cannot be replayed. The solution to this sort of >> problem is going to have to involve exclusive (i.e. write) directory >> delegations to ensure that whatever transactions one client performs >> cannot interfere with the transactions performed by another. >> >> > > Well, a dumb question from me (borrowing Bruce's line :) ) ... even with > "sync" in place, when server rebooted, the RPC reply cache is gone. How > does linux server handle re-transmitted non-idempotent requests ? Badly! Somebody should figure out whether it would be possible for us to implement persistent sessions in v4.1: http://www.nfsv4-editor.org/draft-17/draft-ietf-nfsv4-minorversion1-17.html#Persistence It looks hard! --b. ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs _______________________________________________ Please note that nfs@lists.sourceforge.net is being discontinued. Please subscribe to linux-nfs@vger.kernel.org instead. http://vger.kernel.org/vger-lists.html#linux-nfs