If the operating system becomes corrupted for any reason, you need to restore it from CD-ROM. You may also want to restore the operating system if you are recovering from a system failure. You need to restore the data area if it is damaged or if data is lost. If you have copies of unused or historical data files stored offline, you must restore them to the hard disk drive in order to access them.
There are two methods of restoring the data area of the hard disk drive:
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Full |
Restores the entire data area of the disk drive. |
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Partial |
Restores only a portion of the disk data area. Partial restorations may restore one complete account or file, or restore only the changes made to the data area or to one file or item since the last full backup data from an incremental save backup medium. |
Generally, restoring all or part of the system is done for one of three reasons:
To recover data that has become corrupted
For normal system and file maintenance
To transfer data from one system to another
The method used to restore the system depends on why it is being restored. For example, if data in only one account or file becomes corrupted, it may be necessary to restore only one account or file. On the other hand, if you need to reallocate files or reorganize the disk space, you need to restore the entire data area.
All restorations are performed using physical or virtual logical tape units made with one of the backup Procs. For system and file maintenance, only filesave backup media should be used. For transferring data to another system, only filesave or account-save backup media should be used.
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NOTE |
mvBase uses the diskette drive as a tape drive. Use the tape commands to control physical tape devices, virtual tape devices, and diskette drives. |
Full File-restore
When a full file-restore is performed, the following things occur:
The Overflow Table is initialized and all available space is consolidated into a single block of contiguous frames.
The SYSTEM Dictionary is created.
The Master Dictionary of the first account on the tape is created, and a pointer to it is placed in the SYSTEM Dictionary.
Each data file in that account is then loaded, followed by the items in its associated dictionary.
All commands, Procs, and Q-pointers are restored to the Master Dictionary.
Items 3, 4, and 5 are repeated for each account on the tape.
After the last account is restored, the SYSTEM Dictionary is loaded; Q-pointers and the logon banner are restored.
The same sequence is used for an account-restore, except that the SYSTEM Dictionary is already present and only the D-pointer to the account’s Master Dictionary is added to it.
The following sections describe the various kinds of restoration that are possible.
See Also