Restoring Your Data

HP-UX has a number of utilities for backup and recovery. This discussion focuses on the fbackup and frecover commands used by SAM. Refer to the HP-UX Reference for information on the other backup and restore utilities: cpio, dump, ftio, pax, restore, rrestore, tar, vxdump, and vxrestore.

The following topics are covered:

Determining What Data to Restore

There are two scenarios you will likely encounter for restoring files:

You need to recover one or a few files, usually as a result of an accidental deletion or because the file has been overwritten.
You need to recover all of your files. This is usually part of the system crash recovery process. If you have experienced a file system failure and you suspect that you have corrupt data, refer to System Recovery. If your root disk failed and all the data on the disk is lost, you need to re-install HP-UX; refer to the HP-UX installation guide for your version of HP-UX for details. After you have repaired the file system or replaced the hardware, you can restore your data from your most recent backups.

Ensure that your system can access the device from which you will restore the backup files. You might need to add a disk or tape drive to your system; refer to Configuring HP-UX for Peripherals for more information.

Before Restoring Your Data

Gather the following information and materials before you begin:

A list of files you need to restore
The media on which the data resides
The location on your system to restore the files (original location or relative to some other location)
The device file corresponding to the backup device used for restoring the files

Restoring Your Data Using SAM

You can use SAM or HP-UX commands to restore data. Generally, SAM is simpler than HP-UX commands. If your backup was created by the fbackup command (which SAM uses), you can use SAM or the frecover command to restore the files from your backup.

Restoring Your Data Using HP-UX Commands

The command restores backup files made using the fbackup utility. If your files were not created with fbackup, you will need to use another utility (see Choosing the Backup and Recovery Utility).

To restore files from backups using frecover:

Ensure that you have superuser capabilities.
Ensure that files you intend to restore are not being accessed. The frecover command will not restore files that are active (open) or locked.
Verify that the backup device is properly connected.
Verify that the device is turned on.
Ensure that the device is loaded with the appropriate backup tape.
Restore files using the frecover command.

The -r option to the frecover command is generally used for recovering all files from your backup; the -x option is used for restoring individual files to your system. For complete details, see frecover(1M).

Restoring Files that are NFS Mounted

When restoring files that are NFS mounted to your system, frecover can only restore those files having “other user” write permission. To ensure the correct permissions, log in as superuser on the NFS file server and use the root= option to the /usr/sbin/exportfs command to export the permissions. For more information, see exportfs(1M) and Installing and Administering NFS Services.

Restoring Large Files

If you use fbackup to back up large files (> 2 GB), then those files can only be restored on a large file system. For instance, suppose that you back up a 64-bit file system containing large files; you cannot restore those files to a 32-bit file system that is not enabled for large files.

If a backup contains large files and an attempt is made to restore the files on a file system that does not support large files, the large files will be skipped.

Examples of Restoring Data

Here are some examples of restoring data:

To restore the files using frecover in the directory /home/deptA from a DDS format (DAT) tape:
frecover -x -i /home/deptA
If files are currently in a directory on the disk that is newer than the corresponding files on the tape, frecover will not overwrite the newer version on disk because the -o option is not specified.
To restore the files using frecover from all of the directories under /home/text from a DDS format (DAT) tape into the /tmp directory on the system:
cd /tmp
frecover -x -oF -i /home/text
The -F option removes leading path names from all files on the tape that meet the include criteria. If there are files in the directory /tmp whose names match those coming from tape, specifying the -o option overwrites the version on disk, even if the copy on disk is newer. The /tmp directory now contains all of the files that were backed up from /home/text without the leading directories.

Examples of Restoring Data Remotely

Here are some examples of restoring data remotely (across the network):

To use frecover to restore files across the network, enter:
frecover -r -vf remote-system:/dev/rmt/0m
To use the tar command to restore files across the network, enter:
remsh remote-system -l user dd if=/dev/rmt/0m bs=7k \ | tar -xvf -
If the tar backup used relative paths, the files will be restored relative to the current directory. If absolute paths were used, the files will be restored to their original paths.

Recovering From a System Crash




	IMPORTANT: To protect your data, you should create a recovery system to be used in the event of a system crash.

On 10.x systems

See copyutil(1M) and the documentation accompanying your support media for instructions on creating a recovery system. copyutil is only available from the support media.

On 11.0 systems

On 11.0 systems, you can create a customized System Install Image of an existing system. To obtain the system recovery features and manpages, install Ignite-UX from the Application Release CD-ROM and choose the bundle that matches your release (for example Ignite-UX-11.0).

The following commands support system recovery:

make_recovery - creates the System Recovery Image
check_recovery - checks whether the System Recovery Image needs to be recreated.

For detailed information, see the HP-UX installation and update guide for your version of HP-UX.