Options for backing up of migrated files

Several options control how the Tivoli® Storage Manager backup-archive client backs up migrated files. A backup can skip migrated files, compare stub content, and use a temporary directory that you specify.

skipmigrated

When the skipmigrated option is set to yes, the backup-archive client does not back up or archive any stub files.

If the skipmigrated option is set to no, the backup-archive client can back up stub files during an incremental backup. The default value of the skipmigrated option is no.

checkreparsecontent

The value of checkreparsecontent is applied only when you specify the option skipmigrated=no. If you specify the option checkreparsecontent=yes, the backup-archive client compares reparse point content of the local stub file with the content in Tivoli Storage Manager storage. If the content is the same, the stub file is not backed up again. If the local reparse point content is different from the backed-up content, the local stub file is backed up.

If you specify the option checkreparsecontent=no, the backup-archive client does not compare the reparse point content of the local stub file with the content in Tivoli Storage Manager storage. Differences in the reparse point content are not detected, and no backup is created as a result of the reparse point comparison. If a valid stub file does not exist on the Tivoli Storage Manager, you cannot restore a file as a stub file. In this case, you can restore a complete file instead of a stub file.

The checkreparsecontent option is one condition that can result in a file backup. Other conditions such as changes in file size or security settings are evaluated independently and can also result in a backup.

The reparse point of stub files that were backed up with the HSM for Windows client version 6.1 and earlier does not contain the same information as stub files that were backed up with later versions of the HSM for Windows client. As a result, all version 6.1 and earlier reparse points appear changed to later versions of the backup-archive client. If you set the option checkreparsecontent=yes and skipmigrated=no, the first incremental backup with a later-version backup-archive client creates new backup copies of all version 6.1 and earlier stub files. The new backups in Tivoli Storage Manager storage contain the later-version reparse point information. Subsequent incremental backups create new backup copies of stub files only if the reparse point indicates that the file was changed.

When you set this option, Tivoli Storage Manager checks the reparse point content of the local stub file, which increases the time for a backup operation. Set this option on the first time that you do an incremental backup after either of the following events:

You move migrated files with the dsmmove.exe command.
You change the file space that is used for migration.

Clear this option on subsequent backups.

Table 1. Interaction of options skipmigrated and checkreparsecontent during incremental backup
	skipmigrated=yes	skipmigrated=no
checkreparsecontent=no	A stub file is not backed up.	A stub file is not backed up if only the reparse-point content changed. A stub file can be backed up if other changes occurred.
checkreparsecontent=yes	A stub file is not backed up.	Reparse point content of the local stub file is compared with content in Tivoli Storage Manager storage. A local stub file is backed up if the content does not match. Also, a stub file can be backed up if other changes occurred.

stagingdirectory

The backup-archive client ensures that whenever a stub is backed up, there is a copy of the complete file in the backup pool. If a complete file was not backed up before migration, the migrated copy is temporarily copied back and is backed up. Tivoli Storage Manager associates the backup copy of the complete file with the backup copy of the stub. After the complete file is backed up, the temporary file is removed by the backup-archive client. You can control the location to which the backup-archive client copies the temporary file by using the stagingdirectory option of the backup-archive client. When you use a staging directory for the temporary copy, the stub is not changed. The next backup creates a backup copy of the stub file on the Tivoli Storage Manager server in the backup pool.

If the backup-archive client cannot create a complete backup copy of the migrated file, the backup-archive client does not back up the stub file. For example, if the stub is an orphan with no migrated copy in Tivoli Storage Manager storage, the stub is not backed up.

Tivoli Storage Manager maintains a backup copy of both the complete file and the stub. The backup copy of the complete file does not expire until the backup copy of the stub expires. Either the complete file or the stub can be re-created by using the backup-archive client.

If you set skipmigrated no, files that were not backed up before migration are copied to the staging directory when they are backed up. Many files are copied during a backup in the following situations:

You have many stubs that were backed up with backup-archive client version 5.4 and earlier versions. The files are temporarily copied to the staging directory during backups with backup-archive client version 6.1 and later.
You changed the backup policies for a volume by including for backup many files that were not previously included.
You renamed stubs or directories that contain stubs.
You changed the security settings of stubs or directories that contain stubs, and you configured migration of security attributes.