IBM 7013 J Series, Operator'S Manual

Page: 173 / 297

Using the Service Aids
6-7
To prevent problems that may occur when running this service aid from disk, it is suggested
that this service aid be run from the diagnostics that are loaded from removable media when
possible.
Display/Alter Sector Service Aid
Note: To access this service aid refer to the Disk Maintenance Service Aid.
This service aid allows you to display and alter information on a disk sector. Care must be
used when using this service aid because inappropriate modification to some disk sectors
may result in total loss of all data on the disk. Sectors are addressed by their decimal sector
number. Data is displayed both in hex and in ASCII. To prevent corrupted data from being
incorrectly corrected, the service aid does not display information that cannot be read
correctly.
Disk Media Service Aids
This service aid consists of a Format, Certify, and Erase service aid for each type of hard
disk supported, and Optical Disk service aid for supported optical disks.
•
Certify
Certify reads all of the ID and data fields. It checks for bad data and counts all errors
encountered. If more than 10 hard data errors or more than 1 hard equipment error is
found, the user is prompted to replace the drive. One or less recovered data errors per
megabyte is normal. More than one recoverable data error per megabyte indicates that
the disk should be formatted and certified. Disk errors are not logged during certify.
•
Format
Format writes all the disk. The pattern put on the disk is device dependent, i.e. some
drives may put all 0s, while some may put hexadecimal number 5F. No bad block
reassignment occurs
•
Format and Certify
Format and Certify does the same as format does. After the Format is completed, Certify
is run. This Certify reassigns all bad blocks encountered.
•
Erase Disk
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.