Tivoli Storage Manager AFS/DFS Backup Clients


The DFS File Backup Clients

There are currently four pairs of AIX file backup clients (GUI and command-line) available. This is a result of runtime requirements for the AFS/DFS file backup clients that include requirements for the:

The AFS/DFS file backup clients let you back up and restore AFS/DFS files and directories. In addition, they back up AFS/DFS access control lists (ACLs), and recognize AFS/DFS mount points.

Note:The AFS/DFS versions of TSM executable files are only available for AIX.

Contrasting the AIX File Backup Clients

The current AIX AFS/DFS file backup clients: dsmafs, dsmcafs, dsmdfs, and dsmcdfs, have new functions that are not available in the AIX clients: dsm and dsmc. Table 5 summarizes the differences.

Table 5. Differences Between AIX File Backup Clients

AIX clients What they can do
dsm, dsmc Backup and archive AFS and DFS files and directories.
dsmafs, dsmcafs Back up and archive AFS directories, files, and ACLs. In addition, they backup mount points.
dsmdfs, dsmcdfs Back up and archive DFS directories, files, and ACLs. In addition, they backup mount points.

Select dsmdfs and dsmcdfs

The two commands below contain current DFS file backup functions.

/usr/lpp/adsm/bin/dsmdfs
Starts a GUI session with the current DFS support.

/usr/lpp/adsm/bin/dsmcdfs
Starts a command-line session with the current DFS support.

If you want all users to select the same TSM backup clients with the current DFS support, perform the following steps:

  1. Delete or rename dsm and dsmc.
  2. Rename dsmdfs and dsmcdfs to dsm and dsmc.

Then, users can enter dsm to start a GUI session or dsmc to start a command-line session with the current DFS support.


Setting the Exclude.fs Option

Avoid backing up an entire AFS directory tree beginning with /afs, by entering exclude.fs /afs in a file specified by the inclexcl option. This prevents the /afs directory, from appearing in the backup-archive list, and being included in incremental backups.

For more information about the exclude.fs option, see exclude.


Understanding Potential Backup Problems Caused by DFS Mount Points

DFS lets users add fileset mount points in any directory where the user has write access. The command for performing this task is the DFS fts crmount command.

Note:DFS mount points are UNIX symbolic links with a special syntax.

Mount points can cause problems for a backup program that crosses the tree formed with these mount points. For example, users can create loops by adding DFS fileset mount points in different ways.

A user can also create a mount point for a root fileset of a foreign cell. This action expands the user's subdirectory to include a large tree that would be unimportant to back up.

The following options address these problems:

The following sections describe these options.

Understanding the Dfsbackupmntpnt Option

By default, TSM DFS file backup clients do not cross DFS mount points to avoid problems mentioned in Understanding Potential Backup Problems Caused by DFS Mount Points. AFS mount points and symbolic links require similar backups. For example, if you define /.../almaden.ibm.com/fs/u/luan as a TSM virtual mount point, and you enter this command:

   incremental /.../almaden.ibm.com/fs/u/luan

TSM performs the following incremental backup for /luan:

  1. Backs up any files under /luan that are eligible for backup.
  2. Backs up directories under /luan that are not DFS mount points.
  3. Backs up mount point information for any DFS mount point under /luan.
Note:TSM does not process files or subdirectories under any DFS mount point it encounters under /luan. Processing stops at each mount point.

If you want the file backup clients to cross DFS mount points, set the dfsbackupmntpnt option to no. TSM backs up the mount point as a directory rather than as a symbolic link to the target fileset. The default setting of the dfsbackupmntpnt option is yes. For more information about the dfsbackupmntpnt option, see dfsbackupmntpnt.

When you use the archive client, the directory that is pointed to by the mount point is archived.

Setting the TSM Virtualmountpoint and Domain Options

Exclude /... as a file space using the exclude.fs option. Add TSM virtual mount point definitions in the client system options file for the portions of DFS that you want to back up.

We recommend that you specify a TSM virtual mount point for every DFS fileset to be backed up. Also, set dfsbackupmntpnt to yes (this is the default). For example, to schedule incremental backups of all DFS volumes, define a virtual mount point for each directory that begins a user volume. See the example below:

virtualmountpoint /.../sanjose.ibm.com/fs/u/alice
virtualmountpoint /.../sanjose.ibm.com/fs/u/bob
virtualmountpoint /.../sanjose.ibm.com//fs/u/charlie

Then, you can set corresponding domain options in your client user options file to include the virtual mount points in your default client domain. See the example below:

domain /.../sanjose.ibm.com/fs/u/alice
domain /.../sanjose.ibm.com/fs/u/bob
domain /.../sanjose.ibm.com/fs/u/charlie

You can then schedule a daily incremental back up using the dsmcdfs incremental command through a crontab job (or any other scheduling tool).

For more information about the virtualmountpoint option, see Virtualmountpoint. For more information about the domain option, see domain.

Another Way to Set the Virtualmountpoint and Domain Options.

Another way to set the virtualmountpoint and domain options does not require you to specify all the DFS fileset mount points with TSM virtualmountpoint and domain. For example, instead of listing all DFS-user home directories, specify their parent directory (/.../sanjose.ibm.com/fs/u) as a virtual mount point. This is shown in the example below:

virtualmountpoint /.../sanjose.ibm.com/fs/u

Set the afsbackupmntpnt option to no. The TSM backup client program crosses the DFS fileset mount points in the /.../sanjose.ibm.com/fs/u directory. The client program then backs up all the mounted DFS user filesets. For example, enter the following line in the client system options file:

dfsbackupmntpnt no

Attention: Use this setup with caution because it causes all filesets mounted below /.../sanjose.ibm.com/fs/u to be backed up. This backup operation is vulnerable to potential cyclic mount points which may exist because of DFS mount points created by users. It is also vulnerable to potential mount points created by users who link to the root of a foreign DFS cell.

You can then set corresponding domain options in your client user options file to include the virtual mount point in your default client domain. This is shown in the example below:

domain /.../sanjose.ibm.com/fs/u

You can then schedule a daily incremental back up using the dsmcdfs incremental command through a crontab job (or any other scheduling tool).


Setting the ACLs and DCE Login

Ensure that the dsmcdfs program has the read and list (rl) permissions on all directories and the read (r) permission on all files. To access files, set up the directory and file ACLs correctly.

An AIX user can back up any DFS directory and file by logging on as the DCE root principal.


Restoring DFS Files

Ensure that you have ACL access to the DFS destination directories and files where you restore the data. See TSM for UNIX Using the Backup-Archive Clients for information on how to perform a restore.


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