SCSI block formatter reassign disk format

Q:  My SCSI disk has a few bad blocks.  Is there any way I can avoid swapping the disk for a new one?

Q:  Is there a disk format utility available?

A:  There are two utilities available to handle this sort of thing: reassignblock and formatdisk.  The reassignblock program attempts to remap a known bad sector to a new location on the disk.  It's typically used when messages of the following form appear in the console following disk I/O failure:

      Target 0: MEDIA ERROR; block 7D0H retry
      Target 0: MEDIA ERROR; block 7D0H retry
      ...
      Target 0: MEDIA ERROR; block 7D0H retry
      SCSI Block in error = 2000; Partition a  F.S. sector 1840

This message means that SCSI target 2  encountered an unrecoverable media error at block 2000.  In this case, SCSI block 2000 was associated with File System Block 1840 in disk partition a.  If (and only if) the error is a MEDIA ERROR, the reassignblock utility can be of use.  What we would like to do is repair just that one block, without disturbing the rest of the disk. 


The formatdisk program performs a surface-level format of the entire disk.  When more than a few sectors have all gone bad on a particular disk, it is necessary to reformat the disk. Reformatting involved "wiping the slate clean", so to speak, and re-writing each header on the disk.  This procedure is not to be taken lightly; all user data is, of course, lost.  The formatdisk utility is a last resort before replacing the drive and returning the defective unit to NeXT (or the manufacturer of the drive) for repair. 

You can find the two programs within ~rc/Archive/Binary/BlockUtilities.  Both come with a README file. 

QAxx			

-NeXT-Only-below-this-line-

This stuff doesn't come with the system but we're free to give it out.  Doug Mitchell wrote it and it got Avie's stamp of approval.

Source: 03/12/90	Jayson Adams [surak]
Verify:	10/04/89	Doug Mitchell [dmitch]
Entered: 03/14/90	QAP lord [qap]
Last edit: 03/14/90 surak


