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https://github.com/LINBIT/linstor-docker-volume

Docker volume plugin for LINSTOR
https://github.com/LINBIT/linstor-docker-volume

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Docker volume plugin for LINSTOR

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README 

        
% LINSTORDOCKERVOLUME(8) LINSTOR Docker Volume Plugin User Manual

% Roland Kammerer

% Feb 26, 2019



# NAME



linstor-docker-volume - a volume plugin for docker



# SYNOPSIS



docker volume create [*dockeroptions*] \--driver=linstor [*pluginoptions*] volumename



docker container run [*dockeroptions*] \--volume-driver=linstor \--volume volumename:/data busybox sh



# DESCRIPTION



linstor-docker-volume is a daemon that is socket-activated by

*systemd(1)*. It reads http commands from a local socket and manages

*linstor(8)* resources that are replicated via *DRBD*.



# DRBD TERMINOLOGY

DRBD replicates data on a block level between multiple hosts. With DRBD it is

possible that node alpha reads (and writes) data that is actually stored on

 node bravo. In this case node alpha has a *diskless assignment* and node

bravo has a *diskfull assignment*. While even diskless nodes can access the

data in the cluster, the number of `diskfull assignments` is important,

because it corresponds to the number of full replicas in the cluster. If for

example there are *N* diskfull assignments in the cluster, *N-1* can fail

beyond repair while the data is still stored for operation or recovery on the

last diskfull node.



# OPTIONS



Plugin options are always given as options for the `docker` command and are

therefore prefixed with `--opt`. See the *EXAMPLES* section for further

information.



\--opt fs=*FORMAT*

:   Specify the file system that should be used for the new docker volume.

	 *FORMAT* can be any file system that can be created and mounted on all

	 cluster nodes where the volume should be available. If not specified, it

	 defaults to `ext4`.



\--opt fsopts=*OPTIONS*

:   Specify additional options for file system creation as a string. These options

	 are passed to the *mkfs* command. If not specified, it defaults to the

	 empty string.



\--opt size=*SIZE*

:   Specify the size of the new docker volume in *MB*. The unit is always

	 *MB*. If not specified, it defaults to a size of 100MB.



\--opt storagepool=*NAME*

:   Specify the the name of the storage pool that is used for `disful assigments`.

	 If not specified, it defaults to "drbdpool".



\--opt nodes=*NODES*

:   Specify a list of hosts this docker volume should be deployed to.

    *NODES* is a comma separated list of node names as shown by

	 *linstor node list*. A new volume is always deployed to these nodes as a

	 `diskfull assignment`. Nodes not in the list, but in the DRBD cluster get a

	 `diskless assignment` whenever needed. If not specified, it defaults to the

	 empty list. See `--opt replicas` and the end of the section for further

	 information about the interaction between these two options.



\--opt replicas=*COUNT*

:   Specify the number of nodes this volume should be deployed `diskfull`. All

    other nodes in the DRBD cluster get a `diskless assignment`. If not given

	 it defaults to 2. See `--opt nodes` and the end of the section for

	 further information about the interaction between these two options.



If none of *replicas* and *nodes* is given, the default of *replicas* will be

used. I.e., the new volume will be deployed `diskfull` to two nodes in the

cluster.



If both options, *replicas* and *nodes*, are given, the user given list of

nodes will be taken into account and `replicas` is ignored. I.e., the new

volume will be deployed to the given nodes `diskfull`.



# EXAMPLES

In the following we expect a cluster consisting of three nodes (alpha, bravo,

and charlie).



Example 1 (a typical life cycle):



On node alpha:



    $ docker volume create -d linstor \

                           --opt fs=xfs --opt size=200 lsvol

    $ docker run -it --rm --name=cont \

				 -v lsvol:/data --volume-driver=linstor busybox sh

    $ root@cont: echo "foo" > /data/test.txt

    $ root@cont: exit



On node bravo:



    $ docker run -it --rm --name=cont \

				 -v lsvol:/data --volume-driver=linstor busybox sh

    $ root@cont: cat /data/test.txt

      foo

    $ root@cont: exit

    $ docker volume rm lsvol



Example 2 (one diskfull assignment by name, two nodes diskless):



    $ docker volume create -d linstor --opt hosts=bravo lsvol



Example 3 (one diskfull assignment, no matter where, two nodes diskless):



    $ docker volume create -d linstor --opt replicas=1 lsvol



Example 4 (two diskfull assignments by name, charly diskless):



    $ docker volume create -d linstor --opt hosts=alpha,bravo lsvol



Example 5 (two diskfull assignments, no matter where, one node diskless):



    $ docker volume create -d linstor --opt replicas=2 lsvol



Example 6 (using curl without docker, useful for developers):



    $ curl --unix-socket /run/docker/plugins/linstor.sock \

			  -X POST -H "Content-Type: application/json"

			  -d '{"Name":"linstorvol"}' http://localhost/VolumeDriver.List



# SEE ALSO



`linstor` (8).

The *README* file distributed with linstor-docker-volume is the base for this man page.



The source code and all documentation may be downloaded from

.