Overview

Ceph is a distributed storage and network file system designed to provide excellent performance, reliability, and scalability.

This charm deploys a Ceph cluster.

Usage

The ceph charm has two pieces of mandatory configuration for which no defaults are provided:

fsid:
    uuid specific to a ceph cluster used to ensure that different
    clusters don't get mixed up - use `uuid` to generate one.
         
monitor-secret: 
    a ceph generated key used by the daemons that manage to cluster
    to control security.  You can use the ceph-authtool command to 
    generate one:
      
        ceph-authtool /dev/stdout --name=mon. --gen-key

These two pieces of configuration must NOT be changed post bootstrap; attempting todo this will cause a reconfiguration error and new service units will not join the existing ceph cluster.

The charm also supports specification of the storage devices to use in the ceph cluster.

osd-devices:
    A list of devices that the charm will attempt to detect, initialise and
    activate as ceph storage.
    
    This this can be a superset of the actual storage devices presented to
    each service unit and can be changed post ceph bootstrap using `juju set`.

At a minimum you must provide a juju config file during initial deployment with the fsid and monitor-secret options (contents of cepy.yaml below):

ceph:
    fsid: ecbb8960-0e21-11e2-b495-83a88f44db01 
    monitor-secret: AQD1P2xQiKglDhAA4NGUF5j38Mhq56qwz+45wg==
    osd-devices: /dev/vdb /dev/vdc /dev/vdd /dev/vde

Specifying the osd-devices to use is also a good idea.

Boot things up by using:

juju deploy -n 3 --config ceph.yaml ceph

By default the ceph cluster will not bootstrap until 3 service units have been deployed and started; this is to ensure that a quorum is achieved prior to adding storage devices.

Contact Information

Author: Paul Collins paul.collins@canonical.com, James Page james.page@ubuntu.com Report bugs at: http://bugs.launchpad.net/charms/+source/ceph/+filebug Location: http://jujucharms.com/charms/ceph

Technical Bootnotes

This charm is currently deliberately inflexible and potentially destructive. It is designed to deploy on exactly three machines. Each machine will run mon and osd.

This charm uses the new-style Ceph deployment as reverse-engineered from the Chef cookbook at https://github.com/ceph/ceph-cookbooks, although we selected a different strategy to form the monitor cluster. Since we don't know the names or addresses of the machines in advance, we use the relation-joined hook to wait for all three nodes to come up, and then write their addresses to ceph.conf in the "mon host" parameter. After we initialize the monitor cluster a quorum forms quickly, and OSD bringup proceeds.

The osds use so-called "OSD hotplugging". ceph-disk-prepare is used to create the filesystems with a special GPT partition type. udev is set up to mounti such filesystems and start the osd daemons as their storage becomes visible to the system (or after "udevadm trigger").

The Chef cookbook above performs some extra steps to generate an OSD bootstrapping key and propagate it to the other nodes in the cluster. Since all OSDs run on nodes that also run mon, we don't need this and did not implement it.

See http://ceph.com/docs/master/dev/mon-bootstrap/ for more information on Ceph monitor cluster deployment strategies and pitfalls.