How To: Restore ArcInfo coverages from backup tapes


How do I restore incremental backups of ArcInfo coverages?


An ArcInfo coverage consists of a coverage directory and several files in an INFO sub-directory. The following steps describe how to restore a coverage
from a backup tape that was made as part of a comprehensive backup procedure. In this example, the disks are backed up monthly with a full (level 0) backup. Each week, successive incremental backups are done: level 1, level 2, and level 3, (and level 4 in those months containing 5 weeks). Each day, level 9 backups are done, and written over each week.

Level 0 = all files
Level 1 = all files added/modified since the last level 0
Level 2 = all files added/modified since the last level 1
Level 3 = all files added/modified since the last level 2
Level 9 = all files added/modified since the last level 1,2, or 3

1. Go back to the last full (level 0) backup, and extract both the coverage directory and the entire INFO directory. Create a temporary directory to hold them.

Example: You need to restore a coverage that was accidentally deleted on Thursday in the third week of April. First we need to recover the coverage and INFO directories from the level 0 backup made at the end of March.

2. Go through each incremental level made between the last level 0 and the current date. Restore the coverage and INFO directories over data in the temporary workspace.

Example: Check the level 1 tape for April. The pertinent directories are not found, so we know the coverage was not touched that week. We skip to the level 2 tape for April. The coverage was modified, so we copy the coverage and INFO directories from the tape onto the existing directories in our temporary workspace, thus updating them. The level 3 backup has not yet been completed, as weekly backups are performed on Friday. Therefore, we needn't worry about the weekly tape. Next, we check Monday's level 9 tape, followed by Tuesday's. Since we know the coverage was deleted on Wednesday, we need go no further.

3. At this point the temporary workspace contains the up-to-date coverage directory, and the entire INFO directory as it was the date the coverage was deleted. use ARC COPY to restore the coverage to the original workspace. Do not use the UNIX cp -r command to move the directories, because it will overwrite current INFO files with out-of-date ones.

4. Once the user notifies you that the data has been recovered, delete the temporary workspace.