Tivoli Storage Manager for UNIX Using the Backup-Archive Clients


Appendix A. The AFS and DFS File Backup Clients

There are three pair of AIX file backup clients for the GUI and the command line. Runtime requirements for the AFS/DFS file backup clients include conditions for the following:

The AFS and DFS file backup GUI and command line clients back up, restore, archive, and retrieve:

In addition, backup clients recognize AFS/DFS mount points.

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

Contrasting AIX File Backup Clients

The current AIX AFS and DFS file backup clients (dsmafs, dsmcafs, dsmdfs, and dsmcdfs) include dsm and dsmc functions that are not available in AIX clients. See the table, Table 32, for a summary of the differences.

Table 32. Differences Between AIX File Backup Clients

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

Select Backup Functions

The commands below contain current AFS and DFS file backup functions.

Command Function
/usr/tivoli/tsm/client/ba/bin/dsmafs Starts a GUI session with the current AFS support.
/usr/tivoli/tsm/client/ba/bin/dsmcafs Starts a command line session with the current AFS support.
/usr/tivoli/tsm/client/ba/bin/dsmdfs Starts a GUI session with the current DFS support.
/usr/tivoli/tsm/client/ba/bin/dsmcdfs Starts a command line session with the current DFS support.

If you want all users to select the same Tivoli Storage Manager backup clients with the current AFS or DFS support, perform the following steps:

  1. Delete or rename dsm and dsmc.
  2. Rename dsmafs or dsmdfsand dsmcafs or dsmcdfs to dsm and dsmc.

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

Set the Exclude.fs Option

You may specify that you do not want to back up an entire AFS or DFS directory tree that begins with /afs or /dfs. To accomplish this, enter exclude.fs /afs (or /dfs) in a file specified by the inclexcl option. This prevents the directory from appearing in the backup-archive list and from being included in incremental backups.

For more information about the exclude.fs option, see "Creating an Include-Exclude List" and Exclude Options.


Understanding Potential Backup Problems Caused by Mount Points

Mount points are UNIX symbolic links with special syntax. They can cause problems for a backup program that crosses the tree formed with these mount points. For example, user foo creates an AFS mount point for the user.foo volume in his home directory. User foo also forms a cycle in the directory tree. The backup program enters an infinite loop that looks like this:

   /afs/xyz-cell/u/foo
   /afs/xyz-cell/u/foo/foo
   /afs/xyz-cell/u/foo/foo/foo

  ·
  ·
  ·

User foo can also create a mount point for a root volume of a foreign cell. This expands the subdirectory of user foo to include a tree that would be unimportant to back up.

With DFS, you can create loops by adding DFS fileset mount points in different ways. You also can create a mount point for a root fileset of a foreign cell. This action expands your subdirectory to include a large tree that would be unimportant to back up.

With AFS, you can add volume mount points in any directory where you have write access. The command for performing this task is the AFS fs mkmount command.

With DFS, you can add fileset mount points in any directory where you have write access. The command for performing this task is the DFS fts crmount command.

The following options address these problems:

The Afsbackupmntpnt Option

By default, Tivoli Storage Manager AFS file backup clients do not cross AFS mount points. AFS mount points and symbolic links require similar backups. For example, if you define /afs/almaden.ibm.com/u/luan as a Tivoli Storage Manager virtual mount point and enter this command:

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

Tivoli Storage Manager 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 AFS mount points.
  3. Backs up mount point information for any AFS mount point under /luan:.
Note: Tivoli Storage Manager does not process files or subdirectories under any AFS mount point encountered under /luan:. Processing stops at each mount point.

If you want the file backup clients to cross AFS mount points, set the afsbackupmntpnt option to no. Tivoli Storage Manager backs up the mount point as a directory rather than as a symbolic link to the target volume. For more information about the afsbackupmntpnt option, see Afsbackupmntpnt.

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

The Dfsbackupmntpnt Option

By default, Tivoli Storage Manager DFS file backup clients do not cross DFS mount points. The DFS mount points and symbolic links require similar backups. For example, if you define /.../almaden.ibm.com/fs/u/luan as a Tivoli Storage Manager virtual mount point and you enter this command:

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

Tivoli Storage Manager 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: Tivoli Storage Manager 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. Tivoli Storage Manager backs up the mount point as a directory rather than as a symbolic link to the target fileset. 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.

Set the Virtualmountpoint and Domain Options

Use the exclude.fs option to exclude /afs or /... as a file space. Add Tivoli Storage Manager virtual mount point definitions in your client system options (dsm.sys) file for the portions of AFS or DFS that you want to back up.

Specify a Tivoli Storage Manager virtual mount point for every AFS volume or DFS fileset that you want to back up. Set afsbackupmntpnt to yes (the default) or dfsbackupmntpnt to yes (the default). For example, to schedule incremental backups of all AFS volumes, define a virtual mount point for each directory that begins a user volume. See the example below.

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

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

Set corresponding domain options in your client user options (dsm.opt) file to include the virtual mount points in your default client domain. See the example below.

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

You can then schedule a daily incremental backup using the dsmcafs incremental or 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.

Use Another Method to Set These Options.

You can set the virtualmountpoint and domain options without specifying all the AFS volume mount points or all the DFS fileset mount points. For example, rather than listing all AFS or DFS user home directories, specify their parent directory (/afs/sanjose.ibm.com/u or /.../sanjose.ibm.com/fs/u) as a virtual mount point. See the examples below. For AFS:

virtualmountpoint /afs/sanjose.ibm.com/u

Set the afsbackupmntpnt option to no. The client program crosses the AFS volume mount points in the /afs/sanjose.ibm.com/u directory, then backs up all the mounted AFS user volumes. For example, enter the following line in the client system options file:

afsbackupmntpnt no

Attention: Use this AFS setup with caution because it backs up all volumes mounted below /afs/sanjose.ibm.com/u. When you create AFS mount points, you expose the backup operation to potential cyclic mount points. If you link to the root of a foreign AFS cell, you also expose the backup operation to potential mount points.

For DFS:

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

Set the dfsbackupmntpnt option to no. The 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 DFS setup with caution because it backs up all filesets mounted below /.../sanjose.ibm.com/fs/u. When you create AFS mount points, you expose the backup operation to potential cyclic mount points. If you link to the root of a foreign DFS cell, you also expose the backup operation to potential mount points.

You can set domain options in your client user options file to include the virtual mount point in your default client domain. See the examples below.

For AFS:

domain /afs/sanjose.ibm.com/u
For DFS:
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 backup using the dsmcafs incremental or dsmcdfs incremental command through a crontab job (or any other scheduling tool).


Setting the ACLs and Kerberos Login

Ensure that the dsmcafs program has the read and list (rl) permissions on all directories that you must back up. If you want the backup program to access the files, set up the directory ACLs correctly.

Use the AFS administrator identity to back up any AFS directory.


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 log on as the DCE root principal to back up any DFS directory and file.


Restoring AFS or DFS Files

Ensure that you have ACL access to the AFS or DFS destination directories and files where you want to restore the data.


Setting Processing Options

This section provides information about AFS/DFS options for AFS/DFS file backup clients. The table below lists the processing options and their function.

Table 33. Processing Options

Option Function
afsbackupmntpnt Specifies whether you want Tivoli Storage Manager to see an AFS mount point as a mount point or as a directory.
dfsbackupmntpnt Specifies whether you want Tivoli Storage Manager to see a DFS mount point as a mount point or as a directory.
dfsinclexcl Specifies the path and file name of your DFS include-exclude options file.
domain Specifies the file systems you want to include in your client domain for incremental backup.
exclude Excludes files, directories, and file systems from backup services.
virtualmountpoint Defines a virtual mount point for a file system if you want backup beginning with a specific directory within that file system.


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