Linux and 24x panasonic CD-ROM.

Linux and 24x panasonic CD-ROM.

Post by Ramesh R. R » Thu, 05 Jun 1997 04:00:00



Hi,

Have any of you guys been working with the OEM Panasonic 24x CD-ROM (model
CR-585-B) or any other high speed drives flooding the market these days ?

I purchased one recently and tested out "running Linux directly" off the CD-ROM and the installation went quite smoothly. Somehow I felt that it wasn't
"blazing" fast enough (of course I am *not* expecting hard disk performance
or equivalent) but still it seemed only slightly faster that a 4x.

I also found some info (not relavant to Linux) when I called up panasonic
support. They told me that it is indeed a 24x cd-rom but they don't have
drivers ready yet (for win 95 or NT). The drive came shipped with a floppy
with dos based drivers that are also said to be compatible with the new DVD
drives.

Anyway, I tried the following to check its speed (courtesy CD-ROM HOWTO) :

# time -p dd if=/dev/cdrom of=/dev/null bs=1k count =15000

and it took a real time of 9 secs. That works to about 1666kb/sec and with
CD-ROM ratings of 150kb/sec = 1x this means I have a 11x drive ! This was
ofcourse the first time. The next time I tried, the real time was like
0.63 secs (due to caching I guess) and this doesn't make sense either
because now it is a 158x drive.

Now :
Assuming 11x is more realistic, is this all that the drive can be "pushed"
to ?

Or should I have to recompile a kernel with new settings (or something
like that) ?

Or is it just me :-)

I would appreciate your thoughts and insights.

Ramesh R. Rao

 
 
 

Linux and 24x panasonic CD-ROM.

Post by -r » Fri, 13 Jun 1997 04:00:00



> Hi,

> Have any of you guys been working with the OEM Panasonic 24x CD-ROM (model
> CR-585-B) or any other high speed drives flooding the market these days ?

> I purchased one recently and tested out "running Linux directly" off the CD-ROM and the installation went quite smoothly. Somehow I felt that it wasn't
> "blazing" fast enough (of course I am *not* expecting hard disk performance
> or equivalent) but still it seemed only slightly faster that a 4x.

> I also found some info (not relavant to Linux) when I called up panasonic
> support. They told me that it is indeed a 24x cd-rom but they don't have
> drivers ready yet (for win 95 or NT). The drive came shipped with a floppy
> with dos based drivers that are also said to be compatible with the new DVD
> drives.

> Anyway, I tried the following to check its speed (courtesy CD-ROM HOWTO) :

> # time -p dd if=/dev/cdrom of=/dev/null bs=1k count =15000

> and it took a real time of 9 secs. That works to about 1666kb/sec and with
> CD-ROM ratings of 150kb/sec = 1x this means I have a 11x drive ! This was
> ofcourse the first time. The next time I tried, the real time was like
> 0.63 secs (due to caching I guess) and this doesn't make sense either
> because now it is a 158x drive.

> Now :
> Assuming 11x is more realistic, is this all that the drive can be "pushed"
> to ?

Newer cdrom drives are CLV (Constant linear velocity) instead of CAV
(constant angular velocity).  They spin at different rates depending on
whether you're reading the inside tracks (the "start of the partition"),
or the outside ones (the "end").  PCMag mentions this in their recent
issue.  They noted that 16x's are like 8x near the inside and 16x on
the outside.  Since most cd's aren't full, most data is on the inside,
where the performance is weaker.  AFAIK, all 12x's are 12x across the
disc (why couldn't 16x's be like 12x's on the inside?  I dunno!).
Anyway, the m*of the story was that the 12x are probably the best
deal ($/performance).  Your 11x behavior is probably reasonable, IMHO.
See if you can find a full disc, and read the outside tracks.  That's
easier said than done, but some cdrom benchmark utilities do this....
(I have a copy of cdthru, but it is an OS/2 utility).

Oh, and your scsi card may be affecting things.  My scsi cdrom runs
from my PAS16, which is much weaker than the newer PCI-based bus
mastering SCSI adapters.....

--
                -rb

    Before sending me unsolicited ads, be sure to see:
        http://www.veryComputer.com/
My opinions may or (more likely) may not reflect those of my employer.

 
 
 

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