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Tivoli Storage Manager for UNIX Backup-Archive Clients Installation and User's Guide

Backup Image

The backup image command creates an image backup of one or more volumes on your system.

Notes:

  1. The Tivoli Storage Manager API must be installed to use the backup image command.
  2. Image backup of the Sun QFS file system is not supported.

The Tivoli Storage Manager client must support the raw device type on the specific platform to perform an image backup of a raw device. You can only perform an image backup on local devices. Clustered devices or file systems as well as devices or file systems shared between two or more systems are not supported. If you want to perform an image backup for a file system mounted on a raw device, the raw device must be supported. See Volume Device Type Support for an Image Backup for specific information about supported devices for the backup image command.

Use the include.image option to include a file system or logical volume for image backup, or to specify volume-specific options for image backup.

Offline and Online Image Backup

The traditional offline image backup prevents access to the volume by other system applications during the operation. Use the imagetype=dynamic option to back up the volume as is without remounting it read-only. Corruption of the backup may occur if applications write to the volume while the backup is in progress. In this case, run chdsk after a restore.

For Linux86 only: Tivoli Storage Manager performs an online image backup of file systems residing on a logical volume created by the Linux Logical Volume Manager during which the volume is available to other system applications. Online image backup requires a Version 5.1 Tivoli Storage Manager server.

You can use the imagetype option with the backup image command or the include.image option to specify whether to perform an offline or online image backup. See Imagetype for more information.

The Linux Logical Volume Manager allows the creation of a snapshot of a logical volume while the logical volume itself is still online. The snapshot is created inside the same volume group as the source logical volume. You must ensure that the volume group provides enough free disk space to create the snapshot. The snapshot contains the old data blocks while the modified data is stored in the source logical volume. Use the snapshotcachesize option with the backup image command, in the dsm.opt file, or with the include.image option to specify an appropriate snapshot size so that all old data blocks can be stored while the image backup occurs. A snapshot size of 100 percent will ensure a valid snapshot. See Snapshotcachesize for more information.

Special Considerations when Backing Up Images

When using the backup image command, it is important to be aware of special considerations if you want to do either of the following:

If You Intend to Perform a Point-in-Time Restore Later

To ensure that you can perform point-in-time restores of your file systems, including deleting original files which no longer exist on the logical volume, use a combination of full image backups and the incremental command as described in the steps below:

  1. Perform a full incremental backup of the logical volume, for example:
      dsmc incremental /myfilesystem
    
  2. Perform an image backup of the same logical volume, for example:
      dsmc backup image /myfilesystem
    
  3. Periodically, perform incremental backups, for example:
      dsmc incremental /myfilesystem
    

You must follow these steps in the order shown to ensure that the server records additions and deletions accurately. The following command restores the file system to its exact state as of the last incremental backup:

  dsmc restore image /myfilesystem -incre -del

If you do not follow the steps exactly, two things can occur:

Using the Mode Option

Two types of backup apply to logical volumes: mode=selective (the default) and mode=incremental. The mode=selective option creates and sends a full backup copy of the logical volume to the server. The mode=incremental option sends only those files that were added or changed since the last full image backup to the server. Tivoli Storage Manager ignores the -deletefiles option when the image+image incremental technique of backing up has been used.

If you use the backup image command, first with mode=selective followed by one or more executions with mode=incremental, use the incremental option with the restore image command to apply any changes made after the original image backup. The restore may include files that were later deleted plus the latest versions of files added or changed after the original image backup. If logical volumes are running at or near capacity, an out-of-space condition could result during the restore. For more information, see "Incremental-by-Date". The deletefiles option is allowed on the restore image command, but the client ignores it because the server is not aware of any deleted files.

The following restrictions apply:

Supported Clients

This command is valid for AIX, AIX 5L, HP/UX, Linux86, and Solaris only.

Syntax

                               .-----------------.
                               V                 |
>>-Backup Image--+----------+----+-------------+-+-------------><
                 '- options-'    +- filespec---+
                                 '- "filespec"-'
 
 

Parameters

options
You can use the mode and imagetype command line options with the backup image command. For more information, see Mode.

You can also use these common options: domain.image, exclude.image, include.image, snapshotcachesize. For information, see Chapter 9, Setting Processing Options.

filespec
Specifies the name of one or more logical volumes. If you want to back up more than one file system, separate their names with spaces. Do not use pattern matching characters. If you do not specify a file system, the logical volumes specified with the domain.image option will process. If you do not use the domain.image option to specify file systems to process, an error message displays and no image backup occurs.

Specify the file space over which the logical volume is mounted or the logical volume name. If there is a file system configured in the system for a given volume, you cannot back up the volume with the device name. For example, if /dev/lv01 is mounted on /home you can issue backup image /home but backup image /dev/lv01 will fail with an error: ANS1063E Invalid path specified.

For Sun systems: Specify either a file system name or a raw device name (block device type).

Examples

Task
Back up the /home/test file space over which the logical volume is mounted and perform an image incremental backup that backs up only new and changed files after the last full image backup.

Command: dsmc backup image /home/test -mode=incremental

Task
Perform an offline image backup of the /home directory during which the volume is unmounted and remounted read only.

Command: dsmc backup image /home -imagetype=static

Task
Back up the /dev/lv01 raw logical volume.

Command: dsmc backup image /dev/lv01


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