Application consistency for Hyper-V VMs
vRanger can provide two levels of consistency for Hyper-V® VM backups: file-system consistency and application consistency.
• Crash consistent: A crash-consistent backup is analogous to pulling the plug on a server and then backing up the data. The state of the data that is being backed up with respect to the users of the data is indeterminate. Restoring a crash-consistent image is equivalent to rebooting a server after a hard shut-down.
• Application consistent: vRanger engages the Microsoft Volume Shadow Copy Services (VSS) to put supported applications into a consistent state during a backup. This option ensures that all application writes requests in the machines memory are committed to disk before the snapshot is taken, which means that the application and data can be reliably recovered from the backup archive.To achieve either type of application consistency, you must comply with the following requirements:
• The guest must be operating a Windows® operating system.
Application consistency for physical backups
• File-system consistent: File-system consistency is achieved without any additional tools or configurations. File-system consistency ensures that no file system writes were lost during the backup process.
• Application consistent: vRanger engages the Microsoft VSS to put supported applications into a consistent state during a backup. This option ensures that all application writes requests in the machines memory are committed to disk before the snapshot is taken, which means that the application and data can be reliably recovered from the backup archive.
Understanding retention policies and space-saving technologies
• Full backups: Each savepoint is a complete backup set. Deleting a savepoint has no bearing on the recoverability of any other full savepoint.
• Incremental backups: Incremental backup jobs backup only the blocks that have changed since the last backup — full or incremental. Restoring an incremental savepoint requires the parent full and every incremental between the full and the selected incremental.
• Differential backups: A differential backup contains the data that has changed since the last full backup. Each differential backup includes the contents of the previous differential, which in retention terms means that only the parent full and the most recent differential are required for a restore.Full backups
The following scenario depicts a daily full backup job, with a Savepoint Count of 7:
• Day 1: A full backup is taken.
• Day 2: A full backup is taken.
• Day 3: A full backup is taken.
• Day 4: A full backup is taken.
• Day 5: A full backup is taken.
• Day 6: A full backup is taken.
• Day 7: A full backup is taken.
• Day 8: A full backup is taken. The savepoint from Day 1 is removed.
• Day 9: A full backup is taken. The savepoint from Day 2 is removed.Incremental backups
Incremental backup jobs back up only the blocks that have changed since the last backup — whether it was full or incremental. Restoring an incremental savepoint requires the parent full and every incremental between the full and the selected incremental.
Table 2. Incremental backup retention example
An incremental backup is taken. All savepoints from Day 1 to Day 7 are removed.
Differential backups
Performing optional configurations
Before you set up a backup job, you may want to make the following optional vRanger configurations:
© ALL RIGHTS RESERVED. Terms of Use Privacy Cookie Preference Center