Got DSM-11 running, any manuals online?
paulkoning at comcast.net
Mon Jan 11 08:21:56 CST 2021
> On Jan 9, 2021, at 4:55 PM, David Gesswein via cctalk <cctalk at classiccmp.org> wrote:
> On Sat, Jan 09, 2021 at 01:06:19PM -0700, Warner Losh wrote:
>> DEC standard 144 of any help?
> Thanks for looking.
> That standard is only capable of marking bad sectors. It doesn't have the
> information on where the bad sectors were remapped to. I took a quick look
> at the DSM image. It looks like cylinder 511 is where the controller
> tables are. This cylinder does have a different format. The data didn't
> match this standard.
DEC Std 144 is for older disks, not MSCP. It is the format for telling the OS where the bad sectors are, so the file system creation tool can mark those sectors as unavailable. That doesn't involve remapping (at least not on the OS I know). The bad sectors still exist in the address space, they are just not free so they won't be used.
The MSCP revectoring is a more complex mechanism where the controller tweaks the logical block numbering address space so it appears to be error-free. I assume it's a generalization of the spare-sector feature of the RM80, but as others have pointed out, with MSCP this was an internal matter of the controller and I don't know of any DEC standard for it. In fact, the details are likely to depend on the properties of individual drives.
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