[Simh] Disk Errors

[Kevin Handy]

patrick renouvel wrote:
> God morning,
>
> After migration from physical machine to SimH we have a lot of errors 
> on a disk:
>
> $> analyze/disk/norepair SVLPPCD5:
> Analyze/Disk_Structure for _$1$DUB0: started on 16-FEB-2010 08:20:23..54
>
>
...
>
> I did copy this disk on a scratch one, did a ana/repair and all errors 
> disappeared (with 12 files :-((( )
>
> The same ana/disk/norepair on physical machine gives no errors at all...
>
> Did anybody had this kind of trouble before ?
>

Usually this kind of thing means that there was a problem with
generating the image copy somewhere along the line.


1. How did you create the image file? If you did it on a live system,
    you may have had the directory structure changing while the
    copy was occurring, thus giving you inconsistent results.

2. Did you copy it from the file that created the image to another?
    There are many ways for that to cause problems, such as not
    copying in binary format.

3. Anything else done with the original image? Compression (zip,
    tar, etc)?

4. What system is simh running on? Linux, Windows, etc.
    Windows sometimes likes to play magic tricks. When was the last
    time you did a diskscan? Could it be mangled by drive problems
    on the host system?

Usually there are few problems with disk images, and under Linux,
at least, you can point at the raw access to a CD in the derive, and it
works just as it should (point it to /dev/cdrom for example).