From patchwork Wed May 28 19:53:38 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: mark.doffman@codethink.co.uk X-Patchwork-Id: 4257031 Return-Path: X-Original-To: patchwork-ceph-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E31EE9F358 for ; Wed, 28 May 2014 19:54:04 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DB122202FF for ; Wed, 28 May 2014 19:54:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6C7C202FE for ; Wed, 28 May 2014 19:54:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752010AbaE1Tx7 (ORCPT ); Wed, 28 May 2014 15:53:59 -0400 Received: from ducie-dc1.codethink.co.uk ([185.25.241.215]:33376 "EHLO ducie-dc1.codethink.co.uk" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751694AbaE1Tx7 (ORCPT ); Wed, 28 May 2014 15:53:59 -0400 Received: from localhost (localhost [127.0.0.1]) by ducie-dc1.codethink.co.uk (Postfix) with ESMTP id B724C465247; Wed, 28 May 2014 20:53:57 +0100 (BST) X-Virus-Scanned: Debian amavisd-new at ducie-dc1.codethink.co.uk X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" Received: from ducie-dc1.codethink.co.uk ([127.0.0.1]) by localhost (ducie-dc1.codethink.co.uk [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id V48C3CbKSKU5; Wed, 28 May 2014 20:53:53 +0100 (BST) Received: from Middlesex.cube.mn (24-179-218-191.dhcp.roch.mn.charter.com [24.179.218.191]) by ducie-dc1.codethink.co.uk (Postfix) with ESMTPSA id 0DD23465E80; Wed, 28 May 2014 20:53:49 +0100 (BST) From: mark.doffman@codethink.co.uk To: ceph-devel@vger.kernel.org, sage@inktank.com Cc: Rob Taylor , Mark Doffman Subject: [PATCH v3 2/2] Documentation: Document the cephroot functionality Date: Wed, 28 May 2014 14:53:38 -0500 Message-Id: <90848eb35c97154c216f9cfbdb1fcba5296dd387.1401306206.git.mark.doffman@codethink.co.uk> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Rob Taylor Document using the cephfs as a root device, its purpose, functionality and use. Signed-off-by: Mark Doffman Signed-off-by: Rob Taylor Reviewed-by: Ian Molton --- Documentation/filesystems/{ => ceph}/ceph.txt | 0 Documentation/filesystems/ceph/cephroot.txt | 86 +++++++++++++++++++++++++++ 2 files changed, 86 insertions(+) rename Documentation/filesystems/{ => ceph}/ceph.txt (100%) create mode 100644 Documentation/filesystems/ceph/cephroot.txt diff --git a/Documentation/filesystems/ceph.txt b/Documentation/filesystems/ceph/ceph.txt similarity index 100% rename from Documentation/filesystems/ceph.txt rename to Documentation/filesystems/ceph/ceph.txt diff --git a/Documentation/filesystems/ceph/cephroot.txt b/Documentation/filesystems/ceph/cephroot.txt new file mode 100644 index 0000000..0bcddf7 --- /dev/null +++ b/Documentation/filesystems/ceph/cephroot.txt @@ -0,0 +1,86 @@ +Mounting the root filesystem via Ceph (cephroot) +=============================================== + +Written 2013 by Rob Taylor + +derived from nfsroot.txt: + +Written 1996 by Gero Kuhlmann +Updated 1997 by Martin Mares +Updated 2006 by Nico Schottelius +Updated 2006 by Horms + + + +In order to use a diskless system, such as an X-terminal or printer server +for example, it is necessary for the root filesystem to be present on a +non-disk device. This may be an initramfs (see Documentation/filesystems/ +ramfs-rootfs-initramfs.txt), a ramdisk (see Documentation/initrd.txt), a +filesystem mounted via NFS or a filesystem mounted via Ceph. The following +text describes on how to use Ceph for the root filesystem. + +For the rest of this text 'client' means the diskless system, and 'server' +means the Ceph server. + + +1.) Enabling cephroot capabilities + ----------------------------- + +In order to use cephroot, CEPH_FS needs to be selected as +built-in during configuration. Once this has been selected, the cephroot +option will become available, which should also be selected. + +In the networking options, kernel level autoconfiguration can be selected, +along with the types of autoconfiguration to support. Selecting all of +DHCP, BOOTP and RARP is safe. + + +2.) Kernel command line + ------------------- + +When the kernel has been loaded by a boot loader (see below) it needs to be +told what root fs device to use, and in the case of cephroot, where to find +both the server and the name of the directory on the server to mount as root. +This can be established using the following kernel command line parameters: + +root=/dev/ceph + +This is necessary to enable the pseudo-Ceph-device. Note that it's not a +real device but just a synonym to tell the kernel to use Ceph instead of +a real device. + +If cephroot is not specified, it is expected that a valid mount will be +found via DHCP option 17, Root Path [1] + +cephroot=:/[], + + Monitor addresses separated by commas. Each takes the form + host[:port]. If the port is not specified, the Ceph default + of 6789 is assumed. + + A subdirectory subdir may be specified if a subset of the file + system is to be mounted. + + Standard Ceph options. All options are separated by commas. + See Documentation/filesystems/ceph/ceph.txt for options and + their defaults. + +4.) References + ---------- + +[1] http://tools.ietf.org/html/rfc2132 + +5.) Credits + ------- + + cephroot was derived from nfsroot by Rob Taylor + and Mark Doffman + + The nfsroot code in the kernel and the RARP support have been written + by Gero Kuhlmann . + + The rest of the IP layer autoconfiguration code has been written + by Martin Mares . + + In order to write the initial version of nfsroot I would like to thank + Jens-Uwe Mager for his help.