Sheepdog: Distributed Storage System for KVM

Overview

Sheepdog is a distributed storage system for QEMU. It provides
highly available block level storage volumes to virtual machines.
Sheepdog supports advanced volume management features such as snapshot,
cloning, and thin provisioning.

Sheepdog is an Open Source software, released under the terms of the
GNU General Public License version 2.

For the latest information about Sheepdog, please visit our website at:

http://sheepdog.github.io/sheepdog/

And (recommend for new comers) wiki at:
https://github.com/sheepdog/sheepdog/wiki/

Requirements

• Three or more x86-64 machines
• Corosync cluster engine

Install

Please read the INSTALL file distributed with this package for detailed
instructions on installing or compiling from source.

Usage

• Cluster Management Backends

  Sheepdog uses a cluster management backend to manage membership and broadcast
  messages to the cluster nodes.

  For now, sheepdog can use local driver (for development on a single box),
  corosync (the default), zookeeper and Accord.

• Local Driver

  This driver just makes use of UNIX IPC mechanism to manage the membership
  on a single box, where we start multiple 'sheep' processes to simulate the
  cluster. It is very easy and fast setup and especially useful to test
  functionality without involving any other software.

  To set up a 3 node cluster using local driver in one liner bash:

  $ mkdir /path/to/store
  $ for i in 0 1 2; do sheep -c local /path/to/store/$i -z $i -p 700$i;done
  

• Configure corosync.

  Nearly every modern Linux distribution has x86_64 corosync binaries pre-built
  available via their repositories. We recommend you use these packages if they
  are available on your distribution.

  For debian package based systems:

  $ sudo aptitude install corosync libcorosync-dev
  

  For RPM package based systems:

  $ sudo yum install corosynclib-devel
  

  Reference our wiki, the corosync(8) and corosync.conf(5) man page for further
  details.

• Setup Sheepdog

  1. Launch sheepdog on each machines of the cluster.

     $ sheep /store_dir

     Notes:
     /store_dir is a directory to store objects. The directory must
     be on the filesystem with an xattr support. In case of ext3, you
     need to add 'user_xattr' to the mount options.

     $ sudo mount -o remount,user_xattr /store_device

  2. Make fs

     $ dog cluster format --copies=3

     --copies specifies the number of default data redundancy. In this case,
     the replicated data is stored on three machines.

  3. Check cluster state

     Following list shows that Sheepdog is running on 32 nodes.

     $ dog node list
     Idx Node id (FNV-1a) - Host:Port

     0 0308164db75cff7e - 10.68.13.15:7000

     • 1 03104d8b4315c8e4 - 10.68.13.1:7000
       2 0ab18c565bc14aea - 10.68.13.3:7000
       3 0c0d27f0ac395f5d - 10.68.13.16:7000
       4 127ee4802991f308 - 10.68.13.13:7000
       5 135ff2beab2a9809 - 10.68.14.5:7000
       6 17bd6240eab65870 - 10.68.14.4:7000
       7 1cf35757cbf47d7b - 10.68.13.10:7000
       8 1df9580b8960a992 - 10.68.13.11:7000
       9 29307d3fa5a04f78 - 10.68.14.12:7000
       10 29dcb3474e31d4f3 - 10.68.14.15:7000
       11 29e089c98dd2a144 - 10.68.14.16:7000
       12 2a118b7e2738f479 - 10.68.13.4:7000
       13 3d6aea26ba79d75f - 10.68.13.6:7000
       14 42f9444ead801767 - 10.68.14.11:7000
       15 562c6f38283d09fe - 10.68.14.2:7000
       16 5dd5e540cca1556a - 10.68.14.6:7000
       17 6c12a5d10f10e291 - 10.68.14.13:7000
       18 6dae1d955ca72d96 - 10.68.13.7:7000
       19 711db0f5fa40b412 - 10.68.14.14:7000
       20 7c6b95212ee7c085 - 10.68.14.9:7000
       21 7d010c31bf11df73 - 10.68.13.2:7000
       22 82c43e908b1f3f01 - 10.68.13.12:7000
       23 931d2de0aaf61cf5 - 10.68.13.8:7000
       24 961d9d391e6021e7 - 10.68.13.14:7000
       25 9a3ef6fa1081026c - 10.68.13.9:7000
       26 b0b3d300fed8bc26 - 10.68.14.10:7000
       27 b0f08fb98c8f5edc - 10.68.14.8:7000
       28 b9cc316dc5aba880 - 10.68.13.5:7000
       29 d9eda1ec29c2eeeb - 10.68.14.7:7000
       30 e53cebb2617c86fd - 10.68.14.1:7000
       31 ea46913c4999ccdf - 10.68.14.3:7000

• Create a virtual machine image

  1. Create a 256 GB virtual machine image of Alice.

     $ qemu-img create sheepdog:Alice 256G

  2. You can also convert from existing KVM images to Sheepdog ones.

     $ qemu-img convert ~/amd64.raw sheepdog:Bob

  3. See Sheepdog images by the following command.

     $ dog vdi list
     name id size used shared creation time object id

     Bob 0 2.0 GB 1.6 GB 0.0 MB 2010-03-23 16:16 80000
     Alice 0 256 GB 0.0 MB 0.0 MB 2010-03-23 16:16 40000

• Boot the virtual machine

  1. Boot the virtual machine.

     $ qemu-system-x86_64 -hda sheepdog:Alice

  2. Following command checks used images.

     $ dog vm list
     Name, Vdi size, Allocated, Shared, Status
     ----------------+---------+---------+---------+------------
     Bob, 2.0 GB, 1.6 GB, 0.0 MB, running on xx.xx.xx.xx
     Alice, 256 GB, 0.0 MB, 0.0 MB, not running

• Snapshot

  1. Snapshot

     $ qemu-img snapshot -c name sheepdog:Alice

     -c flag is meaningless currently

  2. After getting snapshot, a new virtual machine images are added as a not-
     current image.

     $ dog vdi list
     name id size used shared creation time object id

     Bob 0 2.0 GB 1.6 GB 0.0 MB 2010-03-23 16:16 80000
     Alice 0 256 GB 0.0 MB 0.0 MB 2010-03-23 16:21 c0000
     s Alice 1 256 GB 0.0 MB 0.0 MB 2010-03-23 16:16 40000

  3. You can boot from the snapshot image by spcifing tag id

     $ qemu-system-x86_64 -hda sheepdog:Alice:1

• Cloning from the snapshot

  1. Create a Charlie image as a clone of Alice's image.

     $ qemu-img create -b sheepdog:Alice:1 sheepdog:Charlie

  2. Charlie's image is added to the virtual machine list.

     $ dog vdi list
     name id size used shared creation time object id

     Bob 0 2.0 GB 1.6 GB 0.0 MB 2010-03-23 16:16 80000
     Alice 0 256 GB 0.0 MB 0.0 MB 2010-03-23 16:21 c0000
     s Alice 1 256 GB 0.0 MB 0.0 MB 2010-03-23 16:16 40000
     Charlie 0 256 GB 0.0 MB 0.0 MB 2010-03-23 16:23 100000

Test Environment

- Debian squeeze amd64
- Debian lenny amd64

===============================================================================
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