NetVault 11.4.5 - Administration Guide

Secondary Copy

With a backup job, you can choose to run a Phase 2 job to create a Secondary Copy, which can be used for off‑site storage and disaster recovery purposes. NetVault Backup provides two methods to create a Secondary Copy: Duplicate and Data Copy.

Duplicate

The Duplicate method creates an exact copy which is linked to the original backup. This method breaks down the backup into segments and copies the segments to the storage device. During restore, the segments from the primary backup and secondary copy are interchangeable. As it is not possible to mix unencrypted segments with encrypted segments during restore, you cannot enable or disable encryption for the Duplicate. If the original saveset is encrypted, the Duplicate method creates an encrypted copy. If the original saveset is not encrypted, this method creates an unencrypted copy.

Data Copy

The Data Copy method breaks down the backup into segments and copies the segments to the backup device. During restore, either the primary backup or the secondary copy is used to recover data; the segments from the primary backup and secondary copy are not interchangeable. Therefore, it is possible to enable encryption for the Data Copy when the primary copy is unencrypted. This option is useful when you want to use the deduplication option for primary backups.


	NOTE: If the primary copy is encrypted, the Data Copy method automatically creates an encrypted saveset.

Backup retirement

A backup can be retained indefinitely or retired after a specified period. NetVault Backup supports generation- and time-based retirement methods for backups. When a backup is retired, its index is deleted from the NetVault Database.

Backup retirement methods

You can specify generation- and time-based retirement methods for backups:

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Generation-based backup retirement: This method specifies the maximum generation count for a Full Backup (that is, the maximum number of Full Backups that are retained for the same data set). Generation-based retirement can only be set for Full Backups. When the number of Full Backups exceeds the specified generation count, the oldest Full Backup is retired.

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Time-based backup retirement: This method specifies the length of time a backup is retained. You can specify the retirement age for backups in number of days, weeks, or years. A backup is retired when the retirement age is reached. Time-based retirement can be set for all backup types (that is, Full, Incremental, and Differential).


	NOTE: When a backup stored on a disk-based storage device (such as NetVault SmartDisk, Quest DR Series System, or Data Domain System) is retired, that backup is deleted from the device. You cannot import the deleted backup by scanning the device.

Retirement rules for dependent backups

If a backup has any dependent backups, you can use the following rules to delete the backup series:

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Retire all backups when the last backup is retired: By default, the retirement of a backup series is deferred until all backups from this series are ready for retirement. The backups from an Incremental series or a Differential series are retired when the last dependent backup from the series is retired.

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Retire all backups when the first backup is retired: NetVault Backup lets you modify the retirement behavior to retire a backup series when the first backup is retired. When this rule is applied, the backups from an Incremental series or a Differential Series are retired when the first backup from the series is retired.

You can choose to apply this rule in the following ways:

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Use the Retirement Timing Control settings to change the default behavior for all backups

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Use the saveset retirement settings to override the default behavior for selected backups

The following examples illustrate the retirement behavior for different backup series:

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Example 1: Incremental Backup series

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Example 2: Differential Backup series

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Example 3: Mixed backups (Full, Incremental, and Differential Backups)

Example 1: Incremental Backup series

In this example, Full Backups are performed on Sunday and Incremental Backups are performed from Monday through Saturday. The retention period is set to seven days.


Day 1	Day 2	Day 3	Day 4	Day 5	Day 6	Day 7
Full Backup	Incremental Backup 1	Incremental Backup 2	Incremental Backup 3	Incremental Backup 4	Incremental Backup 5	Incremental Backup 6

The Incremental Backups depend on the most recent backup of any type (Full, Incremental, or Differential). Therefore, these backups create a single backup series:

Full Backup <- Incremental Backup 1 <- Incremental Backup 2 <- Incremental Backup 3 <- Incremental Backup 4 <- Incremental Backup 5 <- Incremental Backup 6

Depending on the retirement rule that is applied, the backups are retired as follows:

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Retire all backups when the last backup is retired: When you apply this rule, all backups from this series are retired on Day 15.

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Retire all backups when the first backup is retired: When you apply this rule, all backups from this series are retired on Day 8.

Example 2: Differential Backup series

In this example, Full Backups are performed on Sunday and Differential Backups are performed from Monday through Saturday. The retention period is set to seven days.


Day 1	Day 2	Day 3	Day 4	Day 5	Day 6	Day 7
Full Backup	Differential Backup	Differential Backup	Differential Backup	Differential Backup	Differential Backup	Differential Backup

Differential Backups depend on the recent Full Backup. Therefore, these backups create six separate backup series:

Full Backup <- Differential Backup 1

Full Backup <- Differential Backup 2

Full Backup <- Differential Backup 3

Full Backup <- Differential Backup 4

Full Backup <- Differential Backup 5

Full Backup <- Differential Backup 6

Depending on the retirement rule that is applied, the backups are retired as follows:

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Retire all backups when the last backup is retired: When you apply this rule, the backups from this example are retired as follows:


Day 8	Day 9	Day 10	Day 11	Day 12	Day 13	Day 14	Day 15
None	None	Differential Backup 1	Differential Backup 2	Differential Backup 3	Differential Backup 4	Differential Backup 5	Full Backup and Differential Backup 6

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Retire all backups when the first backup is retired: When you apply this rule, all backups from this example are retired on Day 8.

Example 3: Mixed backups (Full, Incremental, and Differential Backups)

In this example, Full Backups are performed on Sunday, Incremental Backups are performed on Monday, Tuesday, and Thursday, and Differential Backups are performed on Wednesday and Saturday. The retention period is set to seven days.


Day 1	Day 2	Day 3	Day 4	Day 5	Day 6	Day 7
Full Backup	Incremental Backup 1	Incremental Backup 2	Differential Backup 1	Incremental Backup 3	Incremental Backup 4	Differential Backup 2

The Differential Backups depend on the recent Full Backup, while the Incremental Backups depend on the most recent backup of any type (Full, Differential, or Incremental). Therefore, these backups create three separate backup series:

Full Backup <- Incremental Backup 1 <- Incremental Backup 2

Full Backup <- Differential Backup 1 <- Incremental Backup 3 <- Incremental Backup 4

Full Backup <- Differential Backup 2

Depending on the retirement rule that is applied, these backups are retired as follows:

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Retire all backups when the last backup is retired: When you apply this rule, the backups from this example are retired as follows:


Day 8	Day 9	Day 10	Day 11	Day 12	Day 13	Day 14	Day 15
None	None	None	Incremental Backup 1 and Incremental Backup 2	None	None	Differential Backup 1, Incremental Backup 3, and Incremental Backup 4	Full Backup and Differential Backup 2