felner@inf.ethz.ch (Tomas Felner) (03/15/89)
I just added a new harddisk to my selfbuilt harddisk-kit. The disk has
some hard errors on the media as indicated on the cover of the disk. To
map them out, I formatted it with the HDX 2.0 from Atari, which has a
Markbad facility that generates a bad sector list (BSL). However, it
didn't find all hard errors, and after running 'Markbad' a few times, I
got several different BSLs. Two entries at the end of the bootblock
indicate the first sector and the number of contiguous sectors holding
the BSL. The BSL looks like this (3 real examples):
000002 550000 002DC8 002D2C ( 2 bad sectors )
000003 AB0000 002DC8 002D2C 0003A6 ( a 3rd bad sector )
000003 030000 00123F 002DC8 002D2C ( different ordering and
another bad sector)
It seems that the first entry indicates the number of bad sectors, and
the third, forth, ... hold the number of the bad sectors. But what does
the second entry mean ? Is it a checksum ? How to get it ???
Since this is the format used by Atari, I guess it will be 'official'.
If I know what the second entry means, I can build the BSL by hand,
adding the bad sectors not found by the formatter (you never know !).
But how about handling that BSL. Does the TOS or any driver support it
or even look at it ? Any comments ? Atari ?
Or even better: the format-command of the Adaptec 4000 controller supports
adding a BSL, so that the bad sectors are mapped out at format-time.
Doing so, you don't have to worry about them any more, because they are
not accessible. Is there any formatter around that accepts such a BSL as
parameter ?
BTW, how did you, netlanders, map out bad sectors before (or now) ? I
was lucky not to have any bad sectors on my other harddisk so far.
- Tomas