VMware plugin backs up the full size of the VMDK, regardless of used disk space or provisioning type (4036429)

Backup and restore behaviour depends on disk type and backup/restore options selected.  We basically have three disk types:

• Thin
• Thick, zeroed on demand ("Zeroed thick")
• Thick, zeroed at creation ("Eager zeroed thick")

So, for full backups without CBT:

• The full disk size is always backed up, regardless of provisioning type. So,
  a 20GB thin provisioned disk that only uses 2GB will result in a 20GB backup.

For full backups with CBT:

• Thin - Only used disk sectors are backed up
• Zeroed thick - Only used disk sectors are backed up
• Eager zeroed thick - All disk sectors are backed up

For incremental backups with CBT:

• Only changed disk sectors are backed up for all disk types

For restores of full backup without CBT:

• All blocks are restore and gets allocated regardless of type of disk provision
  ( Note that once a disk was restored from a non-CBT backup, future CBT enabled
  backups will back up the entire disk)

For restores of Full backup with CBT;

• Thin - Only used sectors are restored
• Zeroed thick - Only used sectors are restored
• Eager zeroed thick - The entire disk is restored

For restores of Incremental backup with CBT:

• Only changed disk sectors are restored for all disk types