Commands which use defect descriptors

Jeff Williams jlw at
Wed Mar 8 14:07:33 PST 1995

With the use of MR heads and the increase in the number of defects
possible on the media, we see that the current commands which use
defect descriptors in the data payloads (Format Unit, Reassign Blocks,
Read Defect Data), do not have the allocation length or the parameter
list length sizes that we need.  For example, a two byte length allows
for 64k bytes.  Each descriptor is 8 bytes.  Therefore only 8k defects
can be handled with some of these commands.

Has anyone else run into this?  If so, how do you solve it?  Should
we create a set of expanded commands for large lists?

Jeffrey L. Williams                                HP TelNet: 396-5030
Disc Controllers Lab             	 Telephone: (1) (208) 396-5030
Disc Mechanism Division                  Facsimile: (1) (208) 396-6858
Hewlett-Packard Co.                    ARPANET: jlw at

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