Open file support for backup operations

The VSS snapshot provider is used for open file support.

VSS is the snapshot provider for Windows.

Some applications can create files and open these files in a way that denies access to all other processes on a Microsoft Windows operating system. Although this is not a common practice, it is sometimes used by database vendors or other applications that might want to limit access to certain files. By restricting access to these files, backup products are prevented from backing up the data. These locked files are not the same as files that are open, or in use. Tivoli® Storage Manager, running without the open file support (OFS) feature, can back up open, or in use files, including files that are open for reading or writing, files that are changing during the backup, executable and dll files that are running, log files that are being appended to, and so on.

You can create OFS or online image backups on workstations with a single NTFS-based, or ReFS-based, C:\ drive.

ANS4987E Error processing '\\machine1\d$\dir1\lockedfile.xyz': the object is in use
by another process

ANS1228E Sending of object '\\machine1\d$\dir1\lockedfile.xyz' failed

Do not use OFS for backing up locked Windows system files, such as the Windows system state. The Tivoli Storage Manager client has advanced features for backing up data that is contained within these files. The backup of the system data that is contained in these files requires extra processing and must be backed up in a group to allow for a successful restore. These files are excluded from the Tivoli Storage Manager file level backup.

For database applications that use certain files for transactional consistency (for example, a recovery log file), it might not be possible to back up and restore these files without database coordination. In these situations, do not back up these database files with the normal Tivoli Storage Manager file level backup. You can exclude these files from backup processing by using an exclude or exclude.dir statement. Tivoli Storage Manager provides a number of Data Protection clients (IBM® Tivoli Storage Manager for Databases, IBM Tivoli Storage Manager for Mail, IBM Tivoli Storage Manager for Application Servers, and so on) which provide this database coordination and backup along with other advanced database backup features. For a current list of Data Protection clients go to this website: http://www.ibm.com/software/tivoli/products/storage-mgr/product-links.html

For private applications or other database products where a Data Protection client is not available, you can use the preschedulecmd option to signal the database or application to do one of the following actions:

• Take the steps necessary to move these files to a consistent and unopen state.
• Bring down the database before the file level backup is started.
• Program or script another method to back up this data and exclude these files from the file level backup. In these cases the OFS feature is not necessary since these files are no longer unavailable or locked by the application. After the file level backup completes, use the postschedulecmd option to bring the database back online or restart the application.

If the time it takes to complete the file level backup is too long to have the open files offline (for example, having the database offline or holding up transactions), use the OFS feature to create a point-in-time snapshot of the volume. In this case, use the presnapshotcmd and postsnapshotcmd options to signal the database or application to coordinate with the backup of these open files. The snapshot, which occurs between the pre-snapshot command and post-snapshot command, generally takes only a few seconds to create. This allows the database or application to resume operations quickly while still allowing Tivoli Storage Manager to perform a full incremental backup of the volume, including the locked files. There are other situations where these application-locked files can be safely backed up and restored on a file-by-file basis. In these situations, you can enable the OFS feature for that volume where the open files exist. Tivoli Storage Manager file level backup then has access to these files and back them up using the Tivoli Storage Manager file level backup and archive operations.

For information about Tivoli Storage Manager Open File Support restrictions and issues, see technote 1248971 .

If open file support has been configured, Tivoli Storage Manager performs a snapshot backup or archive of files that are locked (or "in use") by other applications. The snapshot allows the backup to be taken from a point-in-time copy that matches the file system at the time the snapshot is taken. Subsequent changes to the file system are not included in the backup. You can set the snapshotproviderfs parameter of the include.fs option to none to specify which drives do not use open file support.

To control an open file support operation, you can specify these additional options in your dsm.opt file or as values of the include.fs option: snapshotproviderfs, and presnapshotcmd and postsnapshotcmd.