Backup Modes


Explains the difference between the Itwo main backup types, Virtual Full and Full/Incremental


PHD Virtual Backup provides two main backup modes, Virtual Full and Full/Incremental. Each method can provide specific benefits depending on your particular environment's configuration and the storage type you use. Virtual Full backups are fast backups recommended for backing up to disk while Full/Incremental backups are more suited for backups that will be taken to tape often or for storage that may be slower or not optimized for backups.


Virtual Full Backups

Virtual Full backup mode is the original PHD Virtual Backup method. With virtual full backups, after the initial backup is created, only changes are recorded in each subsequent backup, saving time and network bandwidth in the process. These small files of changes are stored along with links to previous changes all the way back to the initial backup, presenting a virtual full version of the backed up VM available for restore at any point in time. This ensures your backed up virtual machines are always available with no additional requirements.

Figure - Virtual Full Backup mode

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Virtual Full backups are ideal for backing up directly to disk, for example, when using Attached Virtual Disk backup storage with your PHD VBA.


Full/Incremental Backups

Full/Incremental backup mode is a traditional backup method that consists of a single, full backup and many, small incremental files that represent all of the changes from the initial full. After the full backup, incremental backups are created until the next scheduled full is run, then a new set of backups is started.

Figure - Full/Incremental Backup mode

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Backup sets consisting of a single full and all related incremental backups, are referred to as a backup chain. All backups in the chain must be available to successfully recover a Full/Incremental backup as each file relies on changes in all previous files, back to the full backup, in order to create the restored virtual machine. For example, if a full backup is run every Sunday and incremental backups are taken all other days, to restore Wednesday's backup, you will need the full from Sunday and any incremental backups taken on Monday, Tuesday, and Wednesday.

Full/Incremental backups are recommended when backing up to network storage, for backups sent to tape often, and for storage not optimized for backup. For example, when using certain CIFS storage types, you may consider using Full/Incremental backup mode.

Tip:    Creating a new full backup at a minimum once per week, is recommended. Use the Scheduling options of the Backup wizard to set the full schedule for each job.

This concept of backup chains is important to understand, especially when considering Retention, Archiving, and manual deletes. Retention for Full/Incremental backups are based on the backup chains - you can select to keep a specified number of backup chains per VM, unlike Virtual Full backups which are retained according to age. For example, if you run daily Full/Incremental backups with a weekly full on Sundays, the default retention policy will keep two weeks of data (two fulls and 12 increments). When using the Backup Catalog, if you select a single full or a single increment for delete or archive, all backups that belong to the selected full or increment's backup chain will also be removed or archived. Managing Full/Incremental backups by chains preserves the integrity of all backups and ensures any available backups can always be recovered.

Full/Incremental Backup Notes

  • You can run a Full backup at any time by selecting the job in the Jobs page and selecting clicking Run Full.
  • To restore Full/Incremental backups that were sent to tape you will need to drop the exported files back into a PHD VBA's backup data store into the exact directory structure from which they were pulled. When replaced, the PHD VBA will display all backups in the Backup Catalog.
  • Renaming a VM that is being backed up with Full/Incremental mode will result in a new Full backup the next time the backup runs.
  • The Backup Report contains a Type column that displays the type of backup (Full or Increment) that was performed for each VM. In some cases, if a disk was changed or added for example, even though an Incremental backup was scheduled, a Full backup will be performed for the entire VM.



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