Data restoration from tape is the process of copying data files back to the storage system from backup tapes that were created using the storage system dump command.
- When to restore data
You restore data from tape when files are deleted from disk but backed up to tape, when files are corrupted, or when no disk slots are available for expansion. - What the restore command recovers
The restore command enables you to recover all the information that you backed up using the dump command. - How the restore command works
The restore command writes file system data from tape to disk using a predefined process. - Information required for using the restore command
Before restoring data with the restore command, you need to ensure that you have the required information, decide where to enter the restore command, and prepare the destination for the restore. - Where to enter the restore command
You can enter the restore command through a Remote Shell connection, such as RSH, or on the console. - Preparing the destination
If you are restoring the backup to its original path, you do not need to prepare the target volume, qtree, or subtree. If you are restoring the backup to a different destination, you must prepare the location. - Restore command syntax
The restore command consists of a set of options that include the restore types and the modifiers. - What restore types are
A restore type specifies the type of restore you are performing. - What modifiers are
Modifiers specify optional actions. - Executing a restore command
You have to perform a series of steps to execute a restore command. - Restoring incremental backups
Incremental restores build on each other the way incremental backups build on the initial level-0 backup. Therefore, to restore an incremental backup, you need all the backup tapes from the level-0 backup through the last backup that you want to restore. - Restoring the entire storage system
You can restore a storage system only to disks that you have initialized. The way you restore an entire storage system depends on whether you backed up each volume in one backup or as individual directories and qtrees. - Restoring individual files and directories
You can restore one or more directories or files from a backup. - Specifying a full restore
A full restore rebuilds the file system, qtree, or subtree that was in the backup that a tape file contains. - What a table-of-contents restore is
You can display a table of contents of the files or qtrees in a tape file. This is useful in determining what files or qtrees are on a tape and their locations. For qtrees, the restore lists the qtree properties. - Specifying a resume restore
If an entire tape file restore is stopped, you can resume the restore and avoid restoring again what has already been restored. - Specifying tape devices in the restore command
When you performed a backup, you specified one or more tape devices. The files written by these devices can be on one or more tapes. When restoring, you have to list the tape devices in the same order that you used in the backup. - Specifying a single tape file on a multifile tape
You can have more than one tape file on a tape. Tape files do not have names. You can restore a single tape file on a tape that contains more than one tape file. This is done by moving the tape to the beginning of the file that is to be restored. - Specifying the restore destination
The destination acts as the root of the backup that you are restoring. You specify a different restore destination if you are restoring the backed up data to a different location. - Specifying the blocking factor during restore
The blocking factor specifies the number of tape blocks that are transferred in each write operation. A tape block is 1 kilobyte of data. When you restore, you must use the same blocking factor that you used for the backup. The default blocking factor is 63. - Displaying detailed status output
You can get information about the progress of a restore on a file-by-file basis. If you have a restore problem, this output can be useful for your own diagnostics, as well as for technical support. Because of the volume of information that needs to be processed by a console, getting detailed output can slow down a restore considerably. - Specifying to ignore inode limitations
If you are sure that the restore consists mostly of files to be updated rather than new files, you can instruct the storage system to ignore the inode limitations. - Specifying automatic confirmations
Automatic confirmation is the automated answering to any restore questions with "yes". - Specifying no ACLs to be restored
You can exclude ACLs from a restore. - Specifying no qtree information
You can omit qtree information from a restore. In such cases, the qtrees are restored as ordinary directories. - Specifying a test restore
You can test a restore by performing a restore that reads the tape, but does not write to the storage system. - Restore examples: Restoring using a remote tape drive
You can perform a storage system restore using a tape drive attached to a remote storage system or a tape drive attached to a Solaris system. - Restore examples: Multiple tape restores
There are different types of multiple tape restores, such as multiple tapes on a single-tape drive, multiple tapes on two single-tape drives, and multiple tapes on a tape stacker.
Related concepts
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Part No. 210-04162_A0
June 2008