Features/QED

Overview

QED is an image format (like qcow2, vmdk, etc) that supports backing files and sparse images.

Status

• Base QED is in qemu.git since 2010-12-17 and will form part of QEMU 0.14.
• Merge plan for additional features:
  • Zero clusters [submitted].
  • Periodic dirty flag flush [submitted].
  • Image streaming [in preparation].

Features

• Open specification
• Fully asynchronous I/O path
• Strong data integrity due to simple design
• Backing files
  • Backing files may be smaller than the QED image
• Sparse files
  • Retains sparseness over non-sparse channels (e.g. HTTP)

Current work

• Outstanding work

Future Features

• Streaming
• Online defragmentation
• [1]
• Parallel submission
• Meta-data scan avoidance