Administrator's Guide


How ADSM Selects Files for Policy Operations

This section describes how ADSM selects files for the following operations:

Incremental Backup

Clients can choose to back up their files using full or partial incremental backup. A full incremental backup ensures that clients' backed-up files are always managed according to policies. Clients should use full incremental backup whenever possible.

If the amount of time for backup is limited, clients may sometimes need to use partial incremental backup. A partial incremental backup should complete more quickly and require less memory. When a client uses partial incremental backup, only files that have changed since the last incremental backup are backed up. Attributes in the management class that would cause a file to be backed up when doing a full incremental backup are ignored. For example, unchanged files are not backed up even when they are assigned to a management class that specifies absolute mode and the minimum days between backups (frequency) has passed.

The server also does less processing for a partial incremental backup. For example, the server does not expire files or rebind management classes to files during a partial incremental backup.

If clients must use partial incremental backups, they should periodically perform full incremental backups to ensure that complete backups are done and backup files are stored according to policies. For example, clients can do partial incremental backups every night during the week, and a full incremental backup on the weekend.

Performing full incremental backups is important if clients want the ability to restore files to a specific time. Only a full incremental backup can detect whether files have been deleted since the last backup. If full incremental backup is not done often enough, clients who restore to a specific time may find that many files that had actually been deleted from the workstation get restored. As a result, a client's file system may run out of space during a restore process. See "Special Considerations: Enabling Point-in-Time Restore for Clients" for more information.

Full Incremental Backup

When a user requests a full incremental backup, ADSM performs the following steps to determine eligibility:

  1. Checks each file against the user's include-exclude list:

  2. Checks the management class of each included file:

  3. Checks the mode, frequency, and serialization defined in the backup copy group.

    Mode
    Specifies whether the file is backed up only if it has changed since the last backup (modified) or whenever a backup is requested (absolute).

    Frequency
    Specifies the minimum number of days that must elapse between backups.

    Serialization
    Specifies how files are handled if they are modified while being backed up and what ADSM does if modification occurs.

Partial Incremental Backup

When a user requests a partial incremental backup, ADSM performs the following steps to determine eligibility:

  1. Checks each file against the user's include-exclude list:

  2. Checks the management class of each included file:

  3. Checks the date and time of the last incremental backup by the client, and the serialization requirement defined in the backup copy group. (Serialization specifies how files are handled if they are modified while being backed up and what ADSM does if modification occurs.)

Selective Backup

When a user requests a selective backup, ADSM performs the following steps to determine eligibility:

  1. Checks the file against any include or exclude statements contained in the user include-exclude list:

  2. Checks the management class of each included file:

An important characteristic of selective backup is that a file is backed up without regard for whether the file has changed. This result may not always be what you want. For example, suppose a management class specifies to keep three backup versions of a file. If the client uses incremental backup, the file is backed up only when it changes, and the three versions in storage will be at different levels. If the client uses selective backup, the file is backed up regardless of whether it has changed. If the client uses selective backup on the file three times without changing the file, the three versions of the file in server storage are identical. Earlier, different versions are lost.

Archive

When a user requests the archiving of a file or a group of files, ADSM performs the following steps to determine eligibility:

  1. Checks the files against the user's include-exclude list to see if any management classes are specified:

  2. Checks the management class for each file to be archived.

Automatic Migration from a Client Node

A file is eligible for automatic migration from a client node if it meets all of the following criteria:


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