Tivoli Storage Manager AFS/DFS Backup Clients


The AFS File Backup Clients

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

The AFS/DFS file backup GUI and command-line clients back up, restore, archive, and retrieve AFS/DFS files, directories, and access control lists (ACLs). In addition, backup clients recognize AFS/DFS mount points.

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

Contrasting the AIX File Backup Clients

The current AIX AFS/DFS file backup clients: dsmafs, dsmcafs, dsmdfs, and dsmcdfs, include new functions that are not available in the AIX clients: dsm and dsmc. Table 4 summarizes the differences.

Table 4. 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 dsmafs and dsmcafs

The two commands below contain current AFS file backup functions.

/usr/lpp/adsm/bin/dsmafs
Starts a GUI session with the current AFS support.

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

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

  1. Delete or rename dsm and dsmc.
  2. Rename dsmafs and dsmcafs 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 AFS 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 AFS Mount Points

AFS lets users add volume mount points in any directory where the user has write access. The command for performing this task is the AFS fs mkmount command.

Note:AFS 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, user foo creates a mount point for user.foo volume in their home directory. User foo also forms a cycle in his or her directory tree. The backup program would enter 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 foo's subdirectory to include a tree that would be unimportant to back up.

The following options address these problems:

The following sections describe these options.

Understanding the Afsbackupmntpnt Option

By default, TSM 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 TSM virtual mount point and you enter this command:

   incremental /afs/almaden.ibm.com/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 AFS mount points.
  3. Backs up mount point information for any AFS mount point under /luan.
Note:TSM does not process files or subdirectories under any AFS mount point it encounters 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. TSM backs up the mount point as a directory rather than as a symbolic link to the target volume. The default setting of the afsbackupmntpnt option is yes. 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.

Setting the TSM Virtualmountpoint and Domain Options

Exclude /afs 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 AFS to be backed up.

We recommend you specify a TSM virtual mount point for every AFS volume to backed up. Also, set afsbackupmntpnt to yes (this is 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

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 /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 back up using the dsmcafs 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 AFS volume mount points with TSM virtualmountpoint and domain. For example, instead of listing all AFS user home directories, specify their parent directory (/afs/sanjose.ibm.com/u) as a virtual mount point. See the example below:

virtualmountpoint /afs/sanjose.ibm.com/u

Set the afsbackupmntpnt option to no. The TSM backup 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 setup with caution because it backs up all volumes mounted below /afs/sanjose.ibm.com/u. AFS mount points created by users have made this backup operation vulnerable to potential cyclic mount points. Potential mount points created by users who link to the root of a foreign AFS cell have also made this backup operation vulnerable.

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

domain /afs/sanjose.ibm.com/u

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


Setting the ACLs and Kerberos Login

The dsmcafs program must have the read and list (rl) permissions on all directories you need to back up. If you want the backup program to access the files, be sure to set up the directory ACLs correctly.

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


Restoring AFS Files

Ensure that you have ACL access to the AFS 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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