Re: CD-ROM settings and hardware resources...

[Bryan Simmons <bsimmo1@gl.umbc.edu>]

On Thu, 2002-10-24 at 03:01, Ray Olszewski wrote:
> At 05:51 PM 10/23/02 -0400, Bryan Simmons wrote:
> >Perhaps dma wasn't the problem.  Here's the output when I execute hdparm
> >on /dev/hdc (my CD-RW):
> >
> >/dev/hdc:
> >  HDIO_GET_MULTCOUNT failed: Input/output error
> >  IO_support   =  1 (32-bit)
> >  unmaskirq    =  1 (on)
> >  using_dma    =  1 (on)
> >  keepsettings =  0 (off)
> >  readonly     =  0 (off)
> >  BLKRAGET failed: Input/output error
> >  HDIO_GETGEO failed: Invalid argument
> >
> >When I try to retrieve the read-ahead setting: hdparm -a /dev/hdc I get:
> >
> >/dev/hdc:
> >  BLKRAGET failed: Input/output error
> >
> >Does anyone know of a web site where I can research these errors?  Or
> >does anyone have an idea, off the top of their heads, why this could be
> >happening?
> 
> 
> I don't have a reference, but I did take a minute to get the same results 
> for my two drives. Both work fine. Here is what I get:
> 
> First, for hdc, which is a DVD drive acessed via IDE --
> 
>          waverly:/home/autovcr# hdparm /dev/hdc
> 
>          /dev/hdc:
>          HDIO_GET_MULTCOUNT failed: Invalid argument
>          IO_support   =  0 (default 16-bit)
>          unmaskirq    =  0 (off)
>          using_dma    =  1 (on)
>          keepsettings =  0 (off)
>          readonly     =  1 (on)
>          readahead    =  8 (on)
>          HDIO_GETGEO failed: Invalid argument
> 
> Now for hdd, my CD-RW drive, accessed via ide-scsi emulation --
> 
>          waverly:/home/autovcr# hdparm /dev/hdd
> 
>          /dev/hdd:
>          HDIO_GET_MULTCOUNT failed: Input/output error
>          IO_support   =  0 (default 16-bit)
>          unmaskirq    =  0 (off)
>          using_dma    =  1 (on)
>          keepsettings =  0 (off)
>          readonly     =  0 (off)
>          BLKRAGET failed: Input/output error
>          HDIO_GETGEO failed: Invalid argument
> 
> And just to complete the comparison, here is one of the same system's hard 
> disks --
> 
>          waverly:/home/autovcr# hdparm /dev/hdb
> 
>          /dev/hdb:
>          multcount    = 16 (on)
>          IO_support   =  0 (default 16-bit)
>          unmaskirq    =  0 (off)
>          using_dma    =  1 (on)
>          keepsettings =  0 (off)
>          readonly     =  0 (off)
>          readahead    =  8 (on)
>          geometry     = 15017/255/63, sectors = 241254720, start = 0
> 
>  From this, I infer that the two errors I see on both removable drives 
> reflect differences between CD drives and hard disks. The BLKRAGET error is 
> somehow associated with use of scsi-ide emulation, but does not interfere 
> with my ordinary use of the drive.
> 
> So ... you might, just as a test, remove the scsi-ide emulation and see if 
> you can then read the problem CD. If not, you can then check the readahead 
> setting and see if it seems to be wrong. 
For some reason, I can't access this setting at all.  it doesn't show up
when using the hdparm /dev/hdc command and when asking for it directly,
hdparm -a /dev/hdc I get an input/output error.


More likely, since the problem is 
> specific to the one disk, there is something unusual about it that needs to 
> be corrected. When it is mounted, does it return sensible results in its 
> listings of "df" and "ls -l"? 
I suppose so.  I can see and at least start to copy all the files on the
disk.  

Can you "dd" it to an iso image? Is it 
> iso9660 compliant?
I really don't know since I'm kinda ignorant to the different
file-system types.

I remember when first installing CD burning software in Windows (please
hear me out) it told me to turn off the read-ahead on the CD-ROM to
allow me to read all CD-R media.  Is this relevant in Linux?

> 
> 
> --
> -------------------------------------------"Never tell me the odds!"--------
> Ray Olszewski					-- Han Solo
> Palo Alto, California, USA			  ray@comarre.com
> -------------------------------------------------------------------------------
> 
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-- 
Regards,

Bryan Simmons 
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