Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:43636 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424233AbcBQWwW convert rfc822-to-8bit (ORCPT ); Wed, 17 Feb 2016 17:52:22 -0500 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.2 \(3112\)) Subject: Re: "Re: [PATCH RFC Version 1 0/6] Request for Comment: NFS4.1 Session Trunking" From: Chuck Lever In-Reply-To: <3B48A59F-638A-45C9-B2E4-2D65C00DE639@netapp.com> Date: Wed, 17 Feb 2016 17:52:03 -0500 Cc: "J. Bruce Fields" , Martin Houry , Linux NFS Mailing List , Trond Myklebust Message-Id: References:

<20160217205929.GF10401@fieldses.org> <3B48A59F-638A-45C9-B2E4-2D65C00DE639@netapp.com> To: "Adamson, Andy" Sender: linux-nfs-owner@vger.kernel.org List-ID: > On Feb 17, 2016, at 5:35 PM, Adamson, Andy wrote: > > >> On Feb 17, 2016, at 3:59 PM, J. Bruce Fields wrote: >> >> On Wed, Feb 17, 2016 at 02:06:35PM -0500, Chuck Lever wrote: >>> >>>> On Feb 17, 2016, at 9:50 AM, Adamson, Andy >>>> wrote: Thanks for testing. As Trond >>>> pointed out, the correct way to indicate multiple hostnames is on >>>> the mount command line >>>> >>>> mount -o minorversion=1 host1,host2,ÃĒâŽÂĶ,hostn:/ / >>> >>> It might be more natural for NFSv4.x to use a referral or a pNFS >>> layout instead. Do you think that's a viable approach? >> >> Seems like an easy application for fs_locations{_info?}. It'd need >> server support too, and I think you probably want this manual method as >> well for now. > > I agree that the manual method is useful as it allows the client admin to decide if the mount requires session trunking. Seems like the server admin is in a better position to know the locations of replicated data. The server can advertise the most up-to-date location information. More scalable than telling every client admin how to set this up. Adding this CLI to mount means it will be around a long time, so we'd better be sure we want to support it for that long. (Yes, I know, who is this "we"). > The fs_locations would need to be requested by the client. I guess we reqest them at every mountâĶ. Yep, and fetch them again every so often. There's no real cache coherency protocol for this information. (That's where a pNFS layout might be more valuable). The Linux server should be able to advertise replicas using the replicas= export option. >> I wonder if the server can easily generate a list of IP addresses to >> advertise automatically? > > Yes - fs_locations! > > â>Andy > >> In which case the whole thing would be >> zero-configuration, which would be nice. >> >> pNFS sounds like overkill. >> >> --b. > > N§ēæėrļyúčØbēXŽķĮ§vØ^)Þš{.nĮ+·Ĩ{ąû"Ø^nrĄöĶzËëhĻčÚ&ĒøŪGŦéhŪ(éÝĒj"úķm§ĸïęäzđÞāþfĢĒ·h§~m -- Chuck Lever