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IBM Tivoli Storage Manager for Space Management for UNIX: User's Guide


Backing Up and Restoring Files

Backing up your files protects against loss or corruption of your data. Use the Tivoli Storage Manager backup-archive client to back up your files regularly, regardless of whether they are resident, migrated, or premigrated. Back up and restore your migrated and premigrated files in the same manner as you back up and restore files that reside on your local file systems.

See IBM Tivoli Storage Manager for UNIX: Backup-Archive Clients Installation and User's Guide for information about backing up and restoring files.


Backing Up, Migrating, and Restoring Your Files

You can back up and migrate your files to the same Tivoli Storage Manager server or to different Tivoli Storage Manager servers. If you back up and migrate files to the same server, the HSM client can verify that current backup versions of your files exist before you migrate them.

To restore stub files rather than backup versions of your files, use the restoremigstate option with the Tivoli Storage Manager backup-archive client restore command. This is useful if one or more of your local file systems is damaged or lost. Your migrated and premigrated files remain intact, and you need only restore your stub files. To recreate stub files for any migrated or premigrated files that are not backed up, use the dsmmigundelete command.

Note:
If you back up and migrate data to tape, use separate tape drives for backed up and migrated data or make the target storage pools at the top of the primary hierarchy reside on disk (recommended). Otherwise, you cannot back up Tivoli Storage Manager-migrated files. A transparent recall can wait a while for the tape drive to become available. To improve performance, migrate your data to disk storage rather than to tape. Performance requirements for migrated data might be stricter than those for backup data.

If you back up files to one server and migrate them to a different server, the HSM client cannot verify that current backup versions of your files exist before you migrate them. Use the backup-archive client to restore the actual backup versions only. You cannot use the backup-archive client to restore stub files for your migrated files. Use the dsmmigundelete command to recreate stub files for any migrated or premigrated files that are lost.

Back Up Your Files Before You Migrate Them

If you back up and migrate files to the same server, you can assign a management class to files specifying that current backup versions of your files must exist on the migration server before the files migrate. The default management class includes this requirement. The HSM client checks for backup versions of files only on the server to which it migrates your files. If a current backup version of a file does not exist on that server, the file is not migrated.

If you back up files to one server and migrate them to a different server, the HSM client cannot verify that current backup versions of your files exist before it migrates them. Any management class that you assign to files must specify that current backup versions are not required prior to migration. Otherwise, you cannot migrate your files.

Back Up Your Files After You Migrate Them

To back up your files after you migrate them, assign a management class to your files that does not include the requirement for an existing backup version.

If you back up files to the same server to which you migrate them, files are copied from the migration destination to the backup destination. Files are not recalled to your local file system.

Valid for AIX JFS file systems only:

A backup of a migrated file signals a recall if it has been touched within the last two minutes. The file is premigrated.

If you back up files to a different server after you migrate them, the backup-archive client accesses the files using:

For more information about recall modes, see "Migrating Your Files".

Back Up and Restore Your Premigrated Files

You can back up a premigrated file in the same manner that you back up a resident file. Whether you back up a file to the same server to which it was premigrated or to a different server, a copy of the file is sent from your local file system to storage. The HSM client does not copy the file from the migration destination to the backup destination.

If you back up and migrate files to the same server, you can:

If you back up and migrate files to a different server, you can:

For more information about restoring backup versions and stub files for migrated or premigrated files, see IBM Tivoli Storage Manager for UNIX: Backup-Archive Clients Installation and User's Guide.

Restore Your Migrated Files

If you back up files after they are migrated to the same server, you can restore migrated files using one of the following methods:

For more information about these options, see Migfileexpiration and Restoremigstate.

If you back up files to one server and migrate them to a different server, use one of the following methods to restore your migrated files:


Recreating Stub Files for Your Migrated Files

If you back up and migrate files to the same server, and backup versions of your files exist, use the backup-archive client to restore your stub files.

If you back up and migrate files to a different server and your stub files are erased or corrupted, use the dsmmigundelete command to recreate them.

Note:
When you use the dsmmigundelete command to recreate stub files for migrated files, stub files are recreated for all eligible migrated files in the file system that you specify. You cannot use this command to recreate stub files for individual files or specific groups of files.

The dsmmigundelete command creates stub files for any premigrated files for which an original file does not exist on your local file system.

When you enter the dsmmigundelete command:

Attention: The dsmmigundelete command does not support hardlinked files. If you attempt to recreate a stub file for a hardlinked file, a stub file is not recreated unless all of the files that are hardlinked together are deleted from your local file system. When one file in a set of hardlinked files is migrated, all of the hardlinked files in the set become stub files. When the dsmmigundelete command recreates a stub file for a hardlinked file, the stub file has the same name as the file that was originally migrated. Stub files are not recreated for any other files that were previously in the hardlinked set of files.

For more information about using the dsmmigundelete command, see dsmmigundelete.


Restoring Your File Systems

If you lose an entire file system and you attempt to restore backup versions of all your files, including those that are migrated and premigrated, your file system might run out of space. If your file system runs out of space during the restore process, the HSM client must begin migrating files to storage to make room for additional restored files, thereby slowing the restore process.

Rather than restoring backup versions of all your files, do one of the following:

Using one of these methods restores your file system to its state as of the last incremental backup. Premigrated files change to a migrated state.

Back Up and Migrate Files to the Same Server

Follow the steps below to restore your file system if you back up and migrate files to the same server and you have backup versions of your migrated and premigrated files. Enter commands to restore your file system in the exact order that is presented. Otherwise, you might not obtain the results that you want.

  1. Follow your operating system instructions to establish the file system again.
  2. Mount the file system. For information about mounting file systems, see Mounting Your File Systems First.
  3. If the /etc/adsm/SpaceMan/config/dsmmigfstab file contains an entry for your file system, remove the entry from the file. Ensure that the file system does not contain the .SpaceMan directory. Otherwise, you will not be able to add space management to your file system.
  4. Add space management to your file system. For information about adding space management, see Adding Space Management to Your File Systems.
  5. Enter the dsmc restore command and set the restoremigstate option to yes (the default). This command is provided with the backup-archive client. For example, to restore the /home file system, enter:
       dsmc restore -restoremigstate=yes -sub=yes "/home/*"
    

    Enter the dsmc restore command with the restoremigstate option set to yes. The HSM client restores backup versions of resident files and restores stub files for migrated and premigrated files.

Back Up and Migrate Files to a Different Server

Follow these instructions to restore your file system if you back up files to one server and migrate them to another, or if backup versions are not available for migrated and premigrated files.

  1. Follow your operating system instructions to establish the file system again.
  2. Mount the file system. For information about mounting file systems, see Mounting Your File Systems First.
  3. If the /etc/adsm/SpaceMan/config/dsmmigfstab file contains an entry for your file system, remove the entry from the file. Ensure that the file system does not contain the .SpaceMan directory. Otherwise, you will not be able to add space management to your file system.
  4. Add space management to your file system. For information about adding space management, see Adding Space Management to Your File Systems.
  5. Enter the dsmc restore command with the dirsonly option to restore the directory structure of your file system. This command is provided with the backup-archive client. For example, to restore the directory structure for the /home file system, enter:
       dsmc restore -dirsonly -sub=yes "/home/*"
    

    When you use the dirsonly option with the dsmc restore command, only those backed-up directories are restored for your file system. For each directory, attributes such as access permissions or, on an AIX workstation, an access control list, are restored.

    When you use the dirsonly option with the dsmc restore command, only those backed up directories for the file systems that you specify are restored.

  6. Enter the dsmmigundelete command to recreate stub files for migrated files, and to create stub files for premigrated files. For example, if you want to recreate stub files for all migrated files and create stub files for all premigrated files in the /home file system that were not marked for expiration on the server, enter:
       dsmmigundelete /home
    
    Note:
    When restoring an entire file system, do not use the expiring option with the dsmmigundelete command unless you want to create stub files for all migrated and premigrated files, whether or not the files were marked for expiration. If you use the expiring option, you might create stub files for migrated or premigrated files that were intentionally deleted from your local file system prior to the problem that caused you to lose your file system.

    For more information about the dsmmigundelete command, see dsmmigundelete.

  7. Enter the dsmc restore command with the replace option set to no to restore backup versions of previously resident files. For example, to restore backup versions of all the remaining files in the /home file system, enter:
       dsmc restore -replace=no -sub=yes "/home/*"
    
    Note:
    The HSM client restores hard links during the restore process if the hard links were backed up.

Restoring A Disk

To restore a disk in the event of disk loss, restore your:

Restoring Your Operating System

If you can run the backup-archive client, you can recover files. If you can run the HSM client, you can recreate stub files for your migrated files and create stub files for your premigrated files. If you lose the file system that contains your Tivoli Storage Manager clients, you must reinstall the clients before you can recover your files. If you lose the file system that contains the operating system and communications software, you must recover them before you can connect to your server. To minimize the impact of such losses, create a set of installation media that will restore your system to a state that permits contact with the server. The installation media should contain:

  1. A startable operating system that permits you to perform basic functions.
  2. A correctly-configured communications program that permits you to establish communications with the server.
  3. A backup-archive client and an HSM client with customized options files. Command-line clients are sufficient.

The files that you need depend upon the communications package that you use. Consult your operating system and communications software manuals for help in setting up your installation media.

Restore Your File Systems

Use these instructions to restore your file systems if you back up and migrate files to the same server. Enter commands to restore your file systems in the exact order that is presented in the following steps. Otherwise, you might not obtain the results that you want.

  1. Reinstall the backup-archive client and the HSM client.
  2. Follow your operating system instructions to establish your native file systems again.
  3. Mount each file system that you want to restore. For information about mounting file systems, see Mounting Your File Systems First.
  4. Add space management to each file system that the HSM client previously managed. For information about adding space management, see Adding Space Management to Your File Systems.
  5. Enter the backup-archive client dsmc restore command with the restoremigstate option set to yes. You can perform this step for one or more file systems at the same time.

    The backup-archive client restores backup versions of resident files and stub files for migrated and premigrated files. For example, to restore the /home file system, enter:

       dsmc restore -restoremigstate=yes -sub=yes "/home/*"
    

Backup Server and Migration Server are Different

To restore file systems to different servers for backup and migration, follow these steps:

  1. Reinstall the backup-archive client and the HSM client.
  2. Follow your operating system instructions to establish your native file systems again.
  3. Mount each file system that you want to restore. For information about mounting file systems, see Mounting Your File Systems First.
  4. Add space management to each file system that the HSM client previously managed. For information about adding space management, see Adding Space Management to Your File Systems.
  5. Enter the dsmc restore command with the dirsonly option to restore the directory structure of each file system. This command is provided with the backup-archive client. You can perform this step at the same time for one or more file systems. For example, to restore the directory structure for the /home file system, enter:
       dsmc restore -dirsonly -sub=yes "/home/*"
    

    When you use the dirsonly option with the dsmc restore command, only those backed up directories for the file systems that you specify are restored. For each directory, attributes such as access permissions or, on an AIX workstation, an access control list, are restored.

  6. Enter the dsmmigundelete command to recreate stub files for migrated files and to create stub files for premigrated files for each file system for which you restored the directory structure. If you enter the dsmmigundelete command without a file system specification, the default is all file systems for which space management is active. Space management is automatically activated for a file system when you add space management to it. For example, if you want to recreate stub files for all migrated files and create stub files for all premigrated files in the /home file system that were not marked for expiration on the server, enter:
       dsmmigundelete /home
    
    Note:
    When you restore a file system, do not use the expiring option with the dsmmigundelete command unless you want to create stub files for all migrated and premigrated files, whether or not the files were marked for expiration. If you use the expiring option, you might create stub files for migrated or premigrated files that were intentionally deleted from your local file system prior to the problem that caused you to lose your file system.

    For more information about the dsmmigundelete command, see dsmmigundelete.

  7. Enter the dsmc restore command with the replace option set to no to restore backup versions of previously resident files. For example, to restore backup versions of all remaining files in the /home file system, enter:
       dsmc restore -replace=no -sub "/home/*"
    
    Note:
    The HSM client restores hard links during the restore process if the hard links were backed up.


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