disk partitioning

[Jeremy Harris]

In article <7247 at sun.uucp> mojo at sun.UUCP (Joseph Moran) writes:
>`SCSI' disks (ST506 and ESDI) let the controller handle forwarding bad
>blocks.  The good side of this is that the UNIX driver should always
>see a perfect disk.  The down side of this is that a bad sector which
>shows up after the original format of the disk can only be "mapped out"
>by using a disk utility to reformat the entire disk.

	The SCSI spec defines an optional command 'reassign blocks' for
normal and WORM disks.

>`SMD' disks (e.g. A "normal" Fujitsu eagle) *CAN* let the controller
>handle the bad block forwarding, but you have more control.  The
>controller can avoid a bad block by "slipping" a sector.  When this
>happens normally a logical sector is slipped to a spare sector on the
>same track.  This way the data is on the same cylinder and track that
>the file system expected.

	Some SCSI controllers do forwarding this way too. There's nothing
in the SCSI spec which says where the replacement blocks have to be.

Jeremy Harris	jgh at gec-mi-at.co.uk	...!mcvax!ukc!hrc63!miduet!jgh