IBM H SERIES RS/6000, User Manual

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This option can be used to overwrite (remove) all data currently stored in user-
accessible blocks of the disk. The Erase Disk option writes one or more 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 ensure that all blocks on the disk are over-
written 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, some blocks may get placed
into the 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 overwritten.
4. Use the drive as you would normally.
5. When the drive is no longer needed and needs to be erased, be sure to run
the same version of the Erase Disk service aid used in step 2.
Note: Using the same version of the Erase Disk service aid is only critical
when bad blocks were found in step 3.
6. Compare the bad blocks recorded in step 3 with those that now appear in
the defect map.
Note: If the saved data and the newly obtained data differ, then all sectors
of this drive cannot be overwritten. The bad blocks on the new list
were not overwritten.
7. If the new bad block list is the same, continue running the service aid to
overwrite the disk with the chosen patterns.
Chapter 7. Using the Service Aids
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