[Info-vax] analyze/disk errors

[Johnny Billquist]

On 2013-12-05 21:39, David Froble wrote:
> abrsvc wrote:
>> The documentation is correct, EXCEPT that badblk.sys is a reserved
>> file that has a particular file id that cannot be changed.  The
>> documentation should have specified that these files won't work this
>> way.  "The badblk.sys file contains a list of suspected bad blocks on
>> the volume that have not yet been turned over to the bad block file."
>> (From VMS File System Internals by Kirby McCoy page 59).
>>
>> So, in this case the documentation was correct, but incomplete.
>>
>> Dan
>
> Now that is interesting.  Always something more to learn.
>
> I've been aware that the file system needed some way to avoid multiple
> attempts to use a block that has been determined as "bad", and the
> mechanism provided was the bad block file/list, so that the block would
> be "in use" and not free for re-use.
>
> I wasn't aware there was an intermediate step.

I'm not sure it's correct either. There are no other bad block file, as 
far as I know. BADBLK.SYS is *it*. That is where bad blocks are placed. 
Suspected or confirmed makes no difference. They are placed in 
BADBLK.SYS, and thus, no other file can grab them. Problem solved. No 
files will have bad blocks (except for BADBLK.SYS, where pretty much all 
blocks are bad, by definition).

	Johnny