Define a backup strategy for Windows file systems

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Defining a backup strategy before you create your backups provides you with the backups that you require to successfully restore or clone your file systems. Your service-level agreement (SLA), recovery time objective (RTO), and recovery point objective (RPO) largely determine your backup strategy.

An SLA defines the level of service that is expected and addresses many service-related issues, including the availability and performance of the service. RTO is the time by which a business process must be restored after a disruption in service. RPO defines the strategy for the age of the files that must be recovered from backup storage for regular operations to resume after a failure. SLA, RTO, and RPO contribute to the data protection strategy.

Backup schedules for Windows file systems

Backup frequency is specified in policies; a backup schedule is specified in the resource group configuration. The most critical factor in determining a backup frequency or schedule is the rate of change for the resource and the importance of the data. You might back up a heavily used resource every hour, while you might back up a rarely used resource once a day. Other factors include the importance of the resource to your organization, your Service Level Agreement (SLA), and your Recover Point Objective (RPO).

An SLA defines the level of service expected and addresses many service-related issues, including the availability and performance of service. An RPO defines the strategy for the age of the files that must be recovered from backup storage for regular operations to resume after a failure. The SLA and RPO contribute to the data protection strategy.

Even for a heavily used resource, there is no requirement to run a full backup more than once or twice a day.

Backup schedules have two parts, as follows:

  • Backup frequency

    Backup frequency (how often backups are to be performed), called schedule type for some plug-ins, is part of a policy configuration. For example, you might configure the backup frequency as hourly, daily, weekly, or monthly, or you can specify None which makes the policy an on-demand-only policy. You can access policies by clicking Settings > Policies.

  • Backup schedules

    Backup schedules (exactly when backups are to be performed) are part of a resource group configuration. For example, if you have a resource group that has a policy configured for weekly backups, you might configure the schedule to back up every Thursday at 10:00 PM. You can access resource group schedules by clicking Resources > Resource Groups.

Number of backups needed for Windows file systems

Factors that determine the number of backups that you need include the size of the Windows file system, the number of volumes used, the rate of change of the file system, and your Service Level Agreement (SLA).

Backup naming convention for Windows file systems

Windows file system backups use the default Snapshot copy naming convention. The default backup naming convention adds a timestamp to Snapshot copy names that helps you identify when the copies were created.

The Snapshot copy uses the following default naming convention: resourcegroupname_hostname_timestamp

You should name your backup resource groups logically, as in the following example:

dts1_mach1x88_03-12-2015_23.17.26

In this example, the syntax elements have the following meanings:

  • dts1 is the resource group name.

  • mach1x88 is the host name.

  • 03-12-2016_23.17.26 is the date and timestamp.

When creating a backup, you can also add a descriptive tag to help identify the backup. In contrast, if you want to use a customized backup naming convention, you need to rename the backup after the backup operation is complete.

Backup retention options

You can choose either the number of days for which to retain backup copies or specify the number of backup copies you want to retain, up to a ONTAP maximum of 255 copies. For example, your organization might require that you retain 10 days of backup copies or 130 backup copies.

While creating a policy, you can specify the retention options for the backup type and the schedule type.

If you set up SnapMirror replication, the retention policy is mirrored on the destination volume.

SnapCenter deletes the retained backups that have retention labels that match the schedule type. If the schedule type was changed for the resource or resource group, backups with the old schedule type label might still remain on the system.

For long-term retention of backup copies, you should use SnapVault backup.