[CentOS] Re: SCSI bad block table display

William L. Maltby CentOS4Bill at triad.rr.com
Fri Dec 7 23:29:19 UTC 2007


On Wed, 2007-12-05 at 17:29 -0800, Hugh E Cruickshank wrote:
> From: Scott Silva Sent: December 5, 2007 16:32
> >
> > on 12/5/2007 4:21 PM Hugh E Cruickshank spake the following:
> > > From: Ross S. W. Walker Sent: December 5, 2007 15:49
> > >> Google 'sdparam'
> > >><snip>

> No, I am definitely thinking SCSI. I would like to get at the same
> information that SCO OSR5 would report with the badtrk utility.
> 
> > Smart
> > utilities usually can only tell you how many spares are used and
> > how many are
> > left, or just if there are more bad sectors than the drive had
> > spares for.
> 
> For SCSI this table should be available for display. According to the
> SCO OSR5 badtrk man page:
> 
>     Bad tracks/blocks listed in the table are ``aliased'' to good
>     tracks/blocks; when a process tries to read or write a track/block
>     listed in the bad track/block table, it is replaced by one of the
>     alias tracks/blocks.
> 
>     The bad track/block table and alias tracks/blocks are stored in the
>     disk partition, after the division table and before division 0.
> 
> Now that I have reread that several times it is starting to sound more
> like this functionality may have been implemented a the OS level and not
> in the drive as I had previously thought. I will have to go back and
> find our for sure.

Don't bother. It was implemented in the OS, including Xenix IIRC. The FS
format had extra tracks reserved for remapping a whole track when one
bad block was found in the original.

> 
> You know it amazing sometimes how you can have a wrong perception in
> your head for years and never have it challenged or have cause to
> question it. When I say years I mean many years. I have had 20+ years
> of using UNIX systems and this is the first time that I have ever
> had cause to question this. Just goes to show you live and learn!

*chuckle* If it ain't broken ...

> <snip>

--
Bill





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