Features/Sheepdog

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Revision as of 07:04, 3 January 2011 by Kazutaka (talk | contribs)

Summary

A distributed storage system for QEMU

Owner

Detailed Summary

Sheepdog is a distributed storage system for QEMU. It provides highly available block level storage volumes that can be attached to QEMU-based virtual machines. Sheepdog scales to several hundreds nodes, and supports advanced volume management features such as snapshot, cloning, and thin provisioning.

The architecture of Sheepdog is fully symmetric; there is no central node such as a meta-data server. This design enables following features.

Linear scalability in performance and capacity When more performance or capacity is needed, Sheepdog can be grown linearly by simply adding new machines to the cluster.

No single point of failure Even if a machine fails, the data is still accessible through other machines.

Easy administration There is no configuration file that defines the cluster's members or roles. When the `sheep` daemon is run on a new machine, Sheepdog will automatically detect the machine via multicast and will add it as a member of the cluster.

Getting Started

Status

  • QEMU 0.13 provides built-in support for sheepdog block devices.

TODOs

generic items

  • add more documentation for users
  • add more documentation for developers
  • add testing tools to avoid regressions
  • output better debug and error messages
  • support architectures other than X86_64, i386

sheep

  • scalability upto several hundreds nodes
  • better data re-balancing
  • remove data objects which are no longer used
  • provide different redundancy levels for each VDI
  • handle network partition failure
  • remove limitation of the number of VMs on the same host
  • better load balancing, performance

collie

  • provide a machine parsable format option
  • show differences between VDIs to backup efficiently

qemu block driver

  • support live migration
  • support snapshot deletion
  • support a variable object size
  • support shrinking image size

Links