Messages in this thread | | | Date | Wed, 15 Jan 2014 10:00:52 -0800 | From | Randy Dunlap <> | Subject | Re: [PATCH v2 2/2] Documentation: Document the cephroot functionality |
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On 01/15/2014 09:26 AM, mark.doffman@codethink.co.uk wrote: > From: Rob Taylor <rob.taylor@codethink.co.uk> > > Document using the cephfs as a root device, its purpose, > functionality and use. > > Signed-off-by: Mark Doffman <mark.doffman@codethink.co.uk> > Signed-off-by: Rob Taylor <rob.taylor@codethink.co.uk> > Reviewed-by: Ian Molton <ian.molton@codethink.co.uk> > --- > 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..deda4f0 > --- /dev/null > +++ b/Documentation/filesystems/ceph/cephroot.txt > @@ -0,0 +1,86 @@ > +Mounting the root filesystem via Ceph (cephroot) > +=============================================== > + > +Written 2013 by Rob Taylor <rob.taylor@codethink.co.uk> > + > +derived from nfsroot.txt: > + > +Written 1996 by Gero Kuhlmann <gero@gkminix.han.de> > +Updated 1997 by Martin Mares <mj@atrey.karlin.mff.cuni.cz> > +Updated 2006 by Nico Schottelius <nico-kernel-nfsroot@schottelius.org> > +Updated 2006 by Horms <horms@verge.net.au> > + > + > + > +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
use, and
> +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 that a valid mount will be
drop duplicate: that
> +found via DHCP option 17, Root Path [1] > + > +cephroot=<monaddrs>:/[<subdir>],<ceph-opts> > + > + <monaddrs> Monitor addresses separated by commas. Each takes the form > + host[:port]. If the port is not specified, the Ceph default > + of 6789 is assumed. > + > + <subdir> A subdirectory subdir may be specified if a subset of the file > + system is to be mounted
mounted.
> + > + <ceph-opts> 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 <rob.taylor@codethink.co.uk> > + and Mark Doffman <mark.doffman@codethink.co.uk> > + > + The nfsroot code in the kernel and the RARP support have been written > + by Gero Kuhlmann <gero@gkminix.han.de>. > + > + The rest of the IP layer autoconfiguration code has been written > + by Martin Mares <mj@atrey.karlin.mff.cuni.cz>. > + > + In order to write the initial version of nfsroot I would like to thank > + Jens-Uwe Mager <jum@anubis.han.de> for his help. >
-- ~Randy
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