cinder-specs/specs/juno/vmdk-backup.rst

Support backup and restore of volumes created by VMDK driver

https://blueprints.launchpad.net/cinder/+spec/vmdk-backup

The volumes created by the VMDK driver are virtual disks stored in datastores managed by ESX or vCenter server. Currently, the backup-create and backup-restore operations are not supported for these volumes. This blueprint proposes adding support for these operations in VMDK driver.

Problem description

The default implementation of backup-create\ backup-restore does the following steps:

• Attach the volume as a block device or file.
• Backup\restore the file by calling backup service.
• Detach the volume.

It uses an instance of InitiatorConnector (determined by the back-end driver protocol) to do the actual\detach. There is no InitiatorConnector for the vmdk protocol and hence the attach\detach fails for volumes created by the VMDK driver. This blueprint proposes adding support for backup-create\ backup-restore for these volumes.

Use Cases

Proposed change

The change involves overriding the default implementations of backup_volume and restore_backup methods in VMwareEsxVmdkDriver. The steps in backup_volume are listed below:

• Create the backing VM if it not found.
• Download the stream-optimized version of the virtual disk corresponding to the volume to a temporary directory.
• Call backup_service.backup() method to backup the stream-optimized virtual disk file.
• Delete the temporary file.

Following are the steps in restore_backup:

• Call backup_service.restore() to download the stream-optimized virtual disk file to a temporary directory.
• If the backing VM doesn't exist (in the case of restoring the backup to create a new volume), import the stream-optimized virtual disk file to create a new backing VM.
• If the backing VM exists, import the stream-optimized virtual disk file to create a temporary VM and reconfigure the backing VM to replace its virtual disk with that of the temporary VM.
• Delete the temporary file and temporary VM.

Alternatives

HTTP read/write: It is possible to create an HTTP connection to read/write from/to a virtual disk file in vCenter/ESX and an adapter can be written for this connection to support some of the file operations required by the backup drivers. This implementation works for both Swift and Ceph backup drivers. But the TSM backup driver raises InvalidBackup exception if the volume to be backed up is not a block device or regular file.

Data model impact

None

REST API impact

None

Security impact

None

Notifications impact

None

Other end user impact

None

Performance Impact

None

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Primary assignee:

vbala <vbala@vmware.com>

Other contributors:

None

Work Items

• backup_volume method
• restore_backup method

Dependencies

None

Testing

None

Documentation Impact

None

References

None