Database backup types

With IBM® Tivoli® Storage Manager for Mail: Data Protection for Microsoft Exchange Server, you can use the common interface in the Volume Shadow Copy Service (VSS) framework to create database backups.

To back up Exchange Server data, you can use the following backup types and backup expiration policies on the Tivoli Storage Manager server.

Backup types

Full (for more information, see Table 1)
Copy (for more information, see Table 2)
Incremental (for more information, see Table 3)
Differential (for more information, see Table 4)

Expiration policies

Version-based expiration
Version-based expiration uses the VERExists and the VERDeleted copy group parameters.
- VERExists
  The maximum number of Exchange Server database backup versions to retain for the databases that exist on the protected Exchange Server system.
- VERDeleted
  The maximum number of Exchange Server database backup versions to retain for the databases that were deleted from the protected Exchange Server system after they were backed up by Tivoli Storage Manager.
Retention-based expiration
Retention-based expiration uses the RETExtra and the RETOnly copy group parameters.
- RETExtra
  The number of days to retain an Exchange Server database backup version after that version becomes inactive. This parameter applies to backup types where it is possible to have more than one version, for example, full, copy, or differential backup types.
- RETOnly
  The number of days to retain the last Exchange Server database backup version of a database that was deleted from the protected Exchange Server system. The RETOnly parameter applies to all backup types, including incremental backup objects that can never have more than one version.

Policy settings on the Tivoli Storage Manager server

The following tables summarize the policy settings for each VSS backup type.

Tip: When you enable circular logging, you cannot use differential or incremental backups.

Table 1. Type: Full backup
Full backup
Description	Data Protection for Exchange Server backs up the specified database and associated transaction logs. Each version of a full backup has the same name because the server recognizes each backup as a new version of the same backup object.
Expiration policies available for selection	Both retention-based and version-based policies
Recommended usage	If you use only a full backup type, you can use either a retention-based or version-based expiration policy to retain the version of the backup in the Tivoli Storage Manager server.

Table 2. Type: Copy backup
Copy backup
Description	Data Protection for Exchange Server backs up the transaction logs and does not delete the log files after the backup. Otherwise, this backup type is similar to a full backup. You can create a full backup of the Exchange Server database without disrupting any backup processes that use an incremental or differential backup. Each version of a copy backup has the same name because the server recognizes each backup as a new version of the same backup object.
Expiration policies available for selection	Only retention-based policies
Recommended usage	You can keep copy backups of the Exchange Server database for retention periods that are different from the periods that you set for the full backup operations For example, legal regulations might require that you keep a monthly backup for several years. To meet this requirement, you can set those monthly backup processes as copy backups. You must define a management class and set the retention parameters to use for copy backups. These definitions must be different than the parameters set for full backups.

Table 3. Type: Incremental backup
Incremental backup
Description	Transaction log files are not deleted if the backup fails. Only one version of an incremental backup object exists at a time because each incremental backup is named with a unique time stamp.Data Protection for Exchange Server software deactivates all incremental backups (and the active differential backup, if one exists) that are associated with a full backup operation, whenever a new full backup operation is done. When you restore an Exchange Server database from an incremental backup, you must complete the following tasks: Restore the last full backup. Restore any other incremental backups that occur between the full backup and the incremental backup. Restore the incremental backup.
Expiration policies available for selection	Only retention-based policies
Recommended usage	Because each incremental backup has a unique name, you cannot use a version-based expiration policy. For incremental backups, you must use retention-based policies. To ensure that incremental backups do not expire before the full backup on which they depend, you must specify the following parameters: In the management class that you use for incremental backups, set a value for the RETOnly parameter. In the management class you use for full backups, set the value of the RETExtra copy group parameter to be equal to the value you set for the RETOnly parameter.

Table 4. Type: Differential backup
Differential backup
Description	Data Protection for Exchange Server backs up transaction logs but does not delete the log files after the backup. For a full backup with only differential backups, the last full backup and the last differential backup contain all the data that is required to restore the database to its most recent state. Subsequent backups create a new version of the differential backup object on the Exchange Server. When you restore an Exchange Server database from a differential backup, you must complete the following tasks: Restore the last full backup. Restore this differential backup, but no other differential backups. Tip: You can use both version-based and retention-based policies to control the expiration of differential backups.
Expiration policies available for selection	Retention-based and version-based policies
Recommended usage	To ensure that differential backups expire at the same time as the full backup on which they depend, it is recommended (for differential backups) that you use a retention-based policy similar to the one used for incremental backups. To use a retention-based expiration policy, in the management class that you use for differential backups, you must specify the following parameters: Set the VERDeleted and VERExists copy group parameters to nolimit. Set the RETExtra and RETOnly parameter values to match the parameter values in the management class that you use for full backups. To limit the number of differential backups for an Exchange Server database, you can use a version-based policy. If you choose to use a version-based expiration policy, do so in combination with retention-based policies to ensure that old, inactive backups expire, even if you no longer use differential backups. If you want to use both a version-based and a retention-based policy, you must specify the following parameters and version control settings: Set the RETExtra and RETOnly parameter values to match the parameter values in the management class that you use for full backups. Set the VERExist parameter to the value you want. Set the VERDeleted parameter to be equal to VERExist.