IBM RS/6000 7025 Personal Computer User Manual


 
patterns to the disk. An additional option allows data in a selectable block to be
read and displayed on the system console.
To use the Erase Disk option, specify the number (0-3) of patterns to be written.
Select the patterns to be written; the patterns are written serially. That is, the
first pattern is written to all blocks. Then the next pattern is written to all blocks,
overlaying the previous pattern. A random pattern is written by selecting the
"Write random pattern?" option.
The Erase Disk service aid has not been certified as meeting the Department of
Defense or any other organizations security guidelines. The following steps
should be followed if the data on the drive is to be overwritten:
1. Run the "Erase Disk" Service Aid to overwrite the data on the drive.
2. Do a format without certify.
3. Run a second pass of the erase service aid.
For a newly installed drive, you can insure that all blocks on the drive will be
overwritten with your pattern if you use the following procedure:
1. Format the drive.
2. Check the defect map by running the Erase Disk Service Aid.
Note: If you use the "Format and Certify" option, there may be some blocks
which get placed into the grown defect map.
3. If there are bad blocks in the defect map, record the information presented
and ensure that this information is kept with the drive. This data is used later
when the drive is to be overwritten.
4. Use the drive as you would normally.
5. When the drive is no longer needed and is to be erased, run the same
version of the Erase Disk Service Aid which was used in step 2.
Note: Using the same version of the service aid is only critical if there were
any bad blocks found in step 3.
6. Compare the bad blocks which were recorded with the drive in step 3 with
those which now appear in the grown defect map.
Note: If there are differences between the saved data and the newly
obtained data, then all of the sectors on this drive cannot be
overwritten. The new bad blocks will not be overwritten.
7. If the bad block list is the same, continue running the service aid to overwrite
the disk with the chosen pattern(s).
Chapter 7. Using the Service Aids 7-11