Virtual Machine Disk Image Compression

Experience with running out of storage

• Need to run lots of Virtual Machines on a laptop – but need more storage?

Background about sparse files, Windows NTFS and VHD

• NTFS Compression, sparse files and operations on them
• UNIX sparse files
• Be Careful with VHDs and Windows XP Compressed Folders
• Why do VHD’s grow?
• What is a VHD file, what is a disk image?

VHD Pre-Compactor & Compactor

When you create a new VM you can pre-allocate all the storage in one shot or let the storage grow on demand. In the latter case, the VM uses a sparse file

• Compact your Microsoft Virtual PC 2004 VHD Files
• Compressing Microsoft Virtual Server 2005 VHD files
• Virtualization with Microsoft Virtual Server 2005 by Roger Dittner, David Rule, Jr., Ken Majors
• How to compress Microsoft Virtual PC 2007 hard disks
• Compressing Microsoft Virtual PC 2007 Images
• Compressing Microsoft Windows Server 2008 Hyper-V disk images

VMDK Wipe & Shrink

• Wipe & Shrink
• Enable compression on individual .vmdk files
• Issues

3rd Party (Not from MSFT & VMW)

• Raxco Software
  • PerfectDisk for VmWare
  • for ESX
• Parallels Compressor
  • Desktop Version
  • Server Version

Rsync: for transferring files between machines

• Rsync Virtual Machine Backups
• Virtualize a server with minimum downtime

Research

• IZO: Applications of Large-Window Compressions to Virtual Machine Management (Mark et al. IBM Almaden, USENIX, Nov 2008)
• CZIP [ppt][paper]
• redundancy elimination within large collections of files
• Data Domain SISL
• Hyperfactor (IBM Data Depulication)
• Network Applicance