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Last pushed: 2 years ago
Short Description
Ceph OSD (object storage daemon)
Full Description

ceph-osd

Run Ceph OSDs in docker

Usage

There are a number of environment variables which are used to configure
the execution of the OSD:

  • CLUSTER is the name of the ceph cluster (defaults to ceph)

If the OSD is not already created (key, configuration, OSD data), the
following environment variables will control its creation:

  • WEIGHT is the of the OSD when it is added to the CRUSH map (default is 1.0)
  • JOURNAL is the location of the journal (default is the journal file inside the OSD data directory)
  • HOSTNAME is the name of the host; it is used as a flag when adding the OSD to the CRUSH map

The old option OSD_ID is now unused. Instead, the script will scan for each directory in /var/lib/ceph/osd of the form <cluster>-<osd-id>.

To create your OSDs simply run the following command:

docker exec <mon-container-id> ceph osd create.

Multiple OSDs

There is a problem when attempting run run multiple OSD containers on a single docker host. See issue #19.

There are two workarounds, at present:

  • Run each OSD with a separate IP address (e.g., use the new Docker 1.5 IPv6 support)
  • Run multiple OSDs within the same container

To run multiple OSDs within the same container, simply bind-mount each OSD datastore directory:

  • docker run -v /osds/1:/var/lib/ceph/osd/ceph-1 -v /osds/2:/var/lib/ceph/osd/ceph-2

BTRFS and journal

If your OSD is BTRFS and you want to use PARALLEL journal mode, you will need to run this container with --privileged set to true. Otherwise, ceph-osd will have insufficient permissions and it will revert to the slower WRITEAHEAD mode.

Note

Re: [https://github.com/Ulexus/docker-ceph/issues/5]

A user has reported a consterning (and difficult to diagnose) problem wherein the OSD crashes frequently due to Docker running out of sufficient open file handles. This is understandable, as the OSDs use a great many ports during periods of high traffic. It is, therefore, recommended that you increase the number of open file handles available to Docker.

On CoreOS (and probably other systemd-based systems), you can do this by creating the a file named /etc/systemd/system/docker.service.d/limits.conf with content something like:

  [Service]
  LimitNOFILE=4096
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