NetBackup Overview - Backup Types

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  • Article ID:000095798

Description

NetBackup 7.6.x features a number of backup types that are included standard, out-of-the-box. Understanding the fundamental behaviors of each backup type will aid in the deployment and ongoing management of a successful backup environment.

Selecting a Type of Backup:

When a policy is created or modified, the "Type of Backup" Attributes panel can be accessed by selecting the Schedules tab.  
The Attributes list displays only the backup attributes available to the current policy.


Backup Type Selection List

*** If the schedule is a relocation schedule created as part of a basic disk staging storage unit, no backup type selection is needed. 

Understanding Standard Backup Types:

There are (5) standard backup types available with NetBackup 7.6.x The following table provides a summary of each standard backup type. 

 
NetBackup 7.6 Backup Types
TypeSummary
Full BackupBacks up all of the files that are specified in the backup selections list for the policy. The files are backed up, regardless of when the files were last modified or backed up. Full backups occur automatically according to schedule criteria. If you run incremental backups, you must also schedule a full backup to perform a complete restore. Use this option if you configure a policy for a raw partition backup (formatted partitions only).
Cumulative Incremental BackupBacks up the files that are specified in the backup selections list that changed since the last full backup. All files are backed up if no previous backup was done. Cumulative incremental backups occur automatically according to schedule criteria. A complete restore requires the last full backup and the last cumulative incremental backup.
***Do not combine differential incremental backups and cumulative incremental backups within the same Windows policy when the incremental backups are based on archive bit (default configuration).
Differential Incremental BackupBacks up the files that changed since the last successful incremental (differential or
cumulative) or full backup. All files are backed up if no previous backup was done.
Differential incremental backups occur automatically according to schedule criteria. A
complete restore requires the last full backup, the last cumulative incremental, and all differential incremental backups that occurred since the last full backup.
User BackupA user initiates a user backup through the Backup, Archive, and Restore client interface. A user backup backs up all files that the user specifies. 
User ArchiveA user initiates a user archive through the Backup, Archive, and Restore client interface. A user archive backup first backs up the files that the user indicates. Then it deletes the files from the local disk if the backup is successful. Archive backups free local disk space while retaining a copy for future use. The copy is kept until the retention period expires.


Standard Backup Type Caveats:

for Cumulative Incremental Backup: 
By default, if the time between file creation and a full or a differential incremental backup is less than 5 minutes, the differential or cumulative incremental backup may yield unexpected results. The backups are successful, but additional files are backed up. This is often due to the client waiting for acknowledgement from the server of the completed backup. The minimum time allowable for this action is 300 seconds. Additionally the archive bit will not be cleared if no response is received from the server which will result in NetBackup backing up all the same data as the previous last backup.


for User Backup: 
User Backups can be run only during 
periods that are defined in the Schedule Start Window tab.

User-added image

User Backups that attempt to run during a closed window will result in the job failing.  



Additional Backup Types:

A total of (8) additional backup types are available with NetBackup 7.6.x through separate license and/or installation of separate agents.

The following table provides summary of these additional (8) backup types.

 

Additional Backup Types
TypeSummary
Application BackupApplies to all database agent clients. This includes Oracle, SAP, SQL and other Databases. The Software Compatibility List details of all supported databases.
Automatic BackupApplies to all database agent clients, except NetBackup for Informix and NetBackup for Oracle.
Automatic Incremental BackupApplies only to NetBackup for Informix clients.
Automatic Cumulative Incremental BackupApplies only to NetBackup for Oracle Clients
Automatic Differential Incremental BackupAn automatic differential incremental backup applies only to NetBackup for Oracle clients.
Automatic Full BackupApplies to NetBackup for Informix and NetBackup for Oracle clients.
Automatic Vault BackupApplies only to Vault policies. The option does not run a backup, but instead runs the command that is specified in the Vault policy’s backup selections list. In this way it starts an automatic, scheduled vault session or vault eject operation.
Vault Catalog BackupUse when the schedule is for a catalog backup policy that Vault uses.

Additional Backup Types Caveats:

for Application Backups: Complete information can be obtained from the related NetBackup Guide for the respective Database. 

for Vault Catalog Backup: Configuration of one of two schedule attribute combinations is required to be selected or the schedule can not be saved. These are,

  • Check and configure Multiple Copies
  • Check Override policy storage selection, Override policy volume pool and specify retention.
  *** The selected storage unit selection should not be "Any Available". 


About Incremental Backups:

In order to utilize an Incremental Backup, a Full Backup must be run and completed successfully. If no full backup is run, the incremental automatically performs the role of a full backup. To determine the retention of differential and cumulative incremental backups to prevent a gap in backup coverage. The following table provides summary of retention requirements for incremental backups.

Retention Requirements for Incremental Backups
TypeRetention Requirements Summary
DifferentialLongerTo restore all files requires the last full backup and all the differential incremental backups that occurred since the last full backup. Therefore, all the differentials must be kept until the next full backup occurs.
CumulativeShorterEach cumulative incremental backup contains all the changes that occurred since the last full backup. Therefore, a complete restore requires only the most recent cumulative incremental in addition to the full backup.

Relative Backup and Restore Times for Incremental Backups
TypeBackup TimeRestore TimeSummary
DifferentialShorterLonger

Less data in each backup, but all differential incremental backups are required since the last full backup for a restore.

This results in a longer restore time.

CumulativeLongerShorterMore data in each backup, but only the last cumulative incremental backup is required for a complete restore (in addition to the full).


You can use a combination of cumulative and differential incremental backups together to get the advantages of both methods.
For example, assume a set of schedules with the following backup frequencies and retention periods.
(Notice that the differential incremental backups occur more often.)

 

Example of Frequency and Retention Periods
FullFrequencyRetention Period
FullSix daysTwo weeks
CumulativeTwo daysFour days
DifferentialOne dayTwo days


The schedules described above will effectively result in the following series of backups.

User-added image

Note: The job from the automatic schedule with a lower frequency (longer period between backups) always takes precedence.
Thus, the above example produces the following results:

  • Every other day a differential incremental backup occurs, which usually has a minimum backup time.
  • On alternate days, a cumulative incremental backup occurs, which requires more time than the differential backup, but not as much time as a full backup.
    The differential backup can now be expired.
  • To recover all files may require (at most), two incremental backups in addition to the most recent full backup. The combination of backups usually means less restore time than if all differential incremental backups were used. The full backups can be done less often if the amount of data being backed up by the incremental backup is small. 


References:

NetBackup 7.6 Administration Guide

Terms of use for this information are found in Legal Notices.

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