Backups

Unitrends uses backups to create recovery points for your data. Backups are run in different modes and are organized into backup groups. Your backup strategies determine which modes you will use.

Unitrends backups fall into two general categories: local backups and backup copies. Local backups are stored on the appliance. These backups are immediately accessible and enable you to meet low RTOs. Backup copies are stored on an off-site target. These backups are duplicates of your local backups, and are used for long-term retention and disaster recovery.

Backup modes determine what data to include in the backup. These modes protect all types of data and apply to all backup types (file-level, image-level, host-level, application, NAS, and iSeries).

While Unitrends supports a variety of backup modes that give you flexibility in protecting your assets, not all backup modes are supported for all assets. When manually creating a backup job for a given asset, only supported modes are available for selection. (For SLA policies, the appliance uses the incremental forever strategy to automatically create jobs. You do not select the modes to use.)

While creating backup jobs, you can select these backup modes: full, incremental, differential, selective, and bare metal (Windows only). In addition to these, the appliance automatically creates synthetic backups as needed. See the following for a description of each:

A full backup captures all data on the asset:

• For file-level backups run with a Unitrends agent, this includes all file system and operating system data required to recover the asset. You can specify data to include or exclude from the full backup.
• For Windows image-level backups run with a Unitrends agent, this includes all disks and volumes. You can specify volumes to include or exclude from the full backup.
• For host-level backups, this includes VM metadata (configuration files) and blocks of all disks attached to the VM. For VMware, AHV, and XenServer, you can specify disks to exclude from the full backup.
• For application backups, all data is included in a full backup.
• For NAS backups, this includes all eligible data stored on the NAS device (see NAS protection using CIFS/NFS or NAS protection using NDMP for details on which items are automatically excluded from backup).
• For iSeries backups, this includes all eligible files, libraries, and objects (see iSeries Backups Overview and Procedures for details on which items are automatically excluded from backup). The backup is of the filesystem and cannot be used to recover the asset. You can specify data to include or exclude from the full backup.
• A successful full backup must exist before a differential or incremental can run.

An incremental captures changes in the protected data since the last successful backup (of any mode). Therefore, incremental backups are smaller and can run more quickly than full backups, but they depend on the previous backups.

The diagram below illustrates incremental backups for an asset. In this example, the incremental runs once a day, but you can schedule them more frequently if desired.

A differential captures changes in the protected data since the last successful full backup. The diagram below illustrates differential backups for an asset. Each differential captures all changes in the protected data since the full backup on Day 1. For example, the differential on Day 4 captures all changes since the full backup on Day 1, including the changes that were already captured by the differentials on Day 2 and Day 3.

A selective backup is run independently of any full, differential, or incremental backup and captures only the data that you have selected. Selective backups can be used only for file-level backups.

A bare metal backup captures the asset's boot and critical system volumes and is used for disaster recovery only. In most cases, a bare metal backup is not needed because file-level or image-level backups can be used to recover the machine (this is the recommended approach). But in some cases a bare metal backup must be used instead. To determine whether bare metal backups are needed for your asset, see Windows Bare Metal Protection and Recovery.

A synthetic backup is a full or differential backup that the Unitrends appliance synthesizes by superimposing the incremental backups on the last successful full backup. It then uses the synthesized backups to create recovery points for quick recovery. Synthetics are also used to create cold backup copies of file-level backups (file-level incrementals cannot be copied directly to cold targets).

The Unitrends appliance uses the following factors to determine when to create a synthetic backup:

• Amount of data being protected on the appliance
• Number of days from the last full backup
• Number of incremental backups since the last full backup
• Load on the appliance

Synthetic backups are created only for these backup types: file-level, image-level, and host-level backups of VMware, Hyper-V, AHV, and XenServer VMs. Synthetic backups are appliance-side only and do not impact the assets or networks. The diagram below illustrates a synthetic backup. For more information, see When are synthetic backups created.

To protect your data, you will likely use a combination of backup modes. Your Unitrends appliance organizes an asset's backups into groups to manage any inter-dependencies between backups. The appliance creates a new group when it runs or synthesizes a full backup. Each subsequent differential or incremental forms a link in the chain of backups that constitute the group. Each link in the chain is necessary for data recovery.

Each backup is a recovery point of the asset at the point in time that the backup ran. To recover data, you select a single backup. You do not need to select any other dependent backups in the backup group. For details, see the Recovery chapters in this guide (listed in the Recovery Overview).

The following diagrams illustrate backup groups:

The diagram below illustrates the incremental forever backup strategy for an asset. The strategy begins by automatically promoting the first scheduled incremental to a full backup. Thereafter, incremental backups run at the times specified in the job schedule. When the appliance determines a new full backup is necessary, it synthesizes a full backup and starts a new backup group.

The diagram below shows two backup groups containing full, differential, and incremental backups.

 

Selective backups exist independently of backup groups. The diagram below illustrates a backup group and selective backups for one asset. Both a selective backup and an incremental backup ran on Day 3. On Day 5, a differential backup and a selective backup ran. However, only the incremental and the differential belong to the group associated with the full backup run on Day 1.

Note:  Selective backups are supported only for file-level protection.

A data protection strategy consists of utilizing one or more of the backup modes described above. For example, the incremental forever strategy consists of the full and incremental backup modes. Your strategy is implemented when you schedule jobs to occur at intervals and times you specify or define SLA policies to automatically create aligning schedules.

Unitrends recommends using the incremental forever backup strategy when possible, where an initial full backup is followed by incrementals at the frequency and times required to meet your RPOs.

In some cases, you will want to use a different backup strategy (such as weekly fulls with incremental or differentials). By manually creating backup schedules, you can customize your backups to fit any strategy, using the backup modes as desired. Examples of cases when you would not use the incremental forever strategy include:

• Protecting assets for which incrementals are not supported (such as Exchange and SharePoint applications, VMware hardware version 4 VMs, and VMware templates).
• Needing to control when full backups are run. (In most cases, this is not an issue since synthetics are run locally on the appliance and do not impact network or asset performance. But you may choose to schedule weekly fulls if appliance resources are taxed at certain times of the day or week.)