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Conference 7.286::atarist

Title:Atari ST, TT, & Falcon
Notice:Please read note 1.0 and its replies before posting!
Moderator:FUNYET::ANDERSON
Created:Mon Apr 04 1988
Last Modified:Tue May 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1433
Total number of notes:10312

1251.0. "bad blocks on non-SCSI drives" by BERN01::RUGGIERO (Markus Ruggiero from Switzerland) Mon Mar 02 1992 05:29

    Hi,

    I need some information.

    SCSI-drives do maintain their own bad sector list. This is independant
    of the filesystem.

    How is this done with non-SCSI drives? In my case I own an Eickman EX60.
    This is essentially an enhanced SH205 to have a total capacity of 60
    MB. The HD-utilites allow me to scan for bad sectors and mark them. How
    are these bad sectors being marked? Is this mark just some sort of
    preallocation in the FAT? In that case I would get overwritten when I
    use some partitions for other filesystems like Spectre.

    On the other hand 40 MB of this drive can be seen with SCSI-tools. Does
    this mean that 20MB are the original Atari HD and the enhancement is
    another 40 MB on the same spindle connected with some sort of SCSI-
    hostadaptor? When this is true it should be possible to use generic
    SCSI badblock handling. The whole thing however claims to be an Adaptek
    controller when tested.

    Who can shed some light on this?


    thanks
    
    ---markus---
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1251.1It's in the FATYNGSTR::WALLACEMon Mar 02 1992 12:2323
>    How is this done with non-SCSI drives?
TOS and DOS mark bad blocks in the FAT, a FAT entry either has a value
indicating the next FAT entry in a chain, that this is the last entry in a
chain, that the entry is unused, OR that the entry is associated with bad
blocks on the disk. In the latter case TOS and DOS will not use the FAT entry
and associated cluster (sectors) on the disk.

>    On the other hand 40 MB of this drive can be seen with SCSI-tools.
What SCSI tools?

>    this mean that 20MB are the original Atari HD and the enhancement is
>    another 40 MB on the same spindle connected with some sort of SCSI-
>    hostadaptor? The whole thing however claims to be an Adaptek
>    controller when tested.
If there is only one drive then it is all accessed in the same manner.
The Adaptek makes your drive look like a SCSI drive to the system.

>   When this is true it should be possible to use generic
    SCSI badblock handling.
I don't think that Adaptek does "SCSI badblock handling", but I could be
remembering this wrong.

	Ray
1251.2PRNSYS::LOMICKAJJeffrey A. LomickaMon Mar 02 1992 14:168
With an Adaptek 4000 compatible controller, the file system (FAT table
in the TOS case) must handle bad block replacement.  With an OMTI
controller, the controller will handle the bad block replacement for
you.  You seem to have an Adaptek, sorry.

Also, if the drive is a 60MB RLL drive, and you do not have an RLL
controller (an MFM controller instead), you will only get 40MB of space
out of it.  Is that what happened?
1251.3more to the confusionBERN01::RUGGIEROMarkus Ruggiero from SwitzerlandMon Mar 02 1992 14:3429
    re .1

    Thanks for confirming the FAT usage for badblock marking.

    >>What SCSI tools?

    I have a Syquest 44MB removeable SCSI drive that came with formating
    and utility software. This software (and Spectre!) sees 40MB of my
    Eickman drive. Some testing showed me that this is the sectornumbers
    from 0 up to whatever. The other 20MB occupy sectors whatever+1 up to
    last (can't remember the actual sector numbers). None of these
    SCSI-related programs can see the whole disk! (The same goes for other
    SCSI hacks like Megamin etc.)

    Besides I think the controller for the Eickman is the 'standard' SH205
    one and I think someone mentioned to me that there is a SCSI bus
    connector on the Atari controller.

    re .2

    I don't know if MFM or RLL but I can get the full 60MB under TOS (eg 6
    partitions with 10MB each). But only 4 of these partitions are seen by
    Spectre and can be converted to Spectre format.
    
    Oh my! It's becoming more and more confusing!


    ---markus---