Subject: Re: Bad sector troubles.
To: Boris Gjenero <>
From: Anders Magnusson <>
List: port-vax
Date: 03/11/1997 20:39:47
> Hmm...  I doubt it.  Take a look at the disktab for an RD53 on MSCP:
> :ns#18:nt#8:nc#963:
> 18*8*963=138672
> Now here are the actual specs for the RD53 which are used for the MFM
> device:
> Sectors/track:17  Read/write heads:8  Cylinders:1024 
> 17*8*1024=139264  (592 more sectors, probably replacements on MSCP)
> If I actually use the real physical specs in edlabel (as you have to
> with the mfm device), then there is no way that some other space for bad
> sector replacement could exist.  I'm using the whole drive.  This brings
> up two questions:
> 1 - Does NetBSD even use the bad sector replacement stuff on the VS2000
> or does it just write straight to real physical sectors? 
No, the driver does not use any sector replacement. If I understand
the Ultrix sdc manual page correct, then bad block replacement are done
in hardware on MVII/MSCP, and software on MV2000. I haven't the slightest
idea of how this should be done...

> 2 - Assuming it does, how do I make sure that it doesn't trash the
> replacements?  Should I just reserve 592 sectors at the end of the
> drive?
You can try; it depends of if bad blocks are remapped by the software
or hardware. ``You cannot more than fail''.

-- Ragge