Backup time deduplication of common virtual disks from virtual machine backup images

A non-transitory computer-readable storage medium (CRM) storing program instructions executable to perform a backup operation comprising:

• detecting that a virtual disk is a common virtual disk, wherein
• the detecting is based, at least in part, on metadata associated with the virtual disk,
• the metadata comprises a globally unique identifier (GUID), wherein
• the GUID indicates that the common virtual disk is shared by a virtual machine and an another virtual machine,
• the common virtual disk stores common configuration data, and
• the common configuration data is deduplicated;
• in response to receiving a request to backup the virtual machine and the another virtual machine, generating a backup image comprising copies of one or more virtual disks associated with the virtual machine and the another virtual machine, and including a single copy of the common virtual disk and a reference to the single copy of the common virtual disk in the backup image;
• and
• receiving a request to restore the virtual machine from the backup image without overwriting the common virtual disk, wherein the restoring comprises
• determining if the reference to the single copy of the common virtual disk has been modified subsequent to performance of the backup operation, and
• in response to the reference being modified, displaying a warning;
• and
• restore only virtual disk that are not common virtual disk from the backup image.

A system comprising:

• one or more processors;
• and a memory coupled to the one or more processors, wherein the memory stores program instructions executable by the one or more processors to perform a backup operation comprising:
• detecting that a virtual disk is a common virtual disk, wherein
• the detecting is based, at least in part, on metadata associated with the virtual disk, the metadata comprises a globally unique identifier (GUID), wherein
• the GUID indicates that the common virtual disk is shared by a virtual machine and an another virtual machine,
• the common virtual disk stores common configuration data, and
• the common configuration data is deduplicated;
• in response to receiving a request to backup the virtual machine and the another virtual machine, generating a backup image comprising copies of one or more virtual disks associated with the virtual machine and the another virtual machine, and including a single copy of the common virtual disk and a reference to the single copy of the common virtual disk in the backup image;
• and
• receiving a request to restore the virtual machine from the backup image without overwriting the common virtual disk, wherein the restoring comprises
• determining if the reference to the single copy of the common virtual disk has been modified subsequent to performance of the backup operation, and
• in response to the reference being modified, displaying a warning;
• and
• restore only virtual disk that are not common virtual disk from the backup image.