Boosting performance when a read-only disc is in the drive

Tom Adelstein adelste at yahoo.com
Mon May 2 03:15:06 UTC 2005


On Mon, 2005-05-02 at 05:47 +0300, ZIYAD A. M. AL-BATLY wrote:
> On Sun, 2005-05-01 at 18:16 -0400, Stephen R Laniel wrote:
> > Is there any way to extract meaningful performance gains from a
> > DVD/CD-RW drive when a read-only CD-ROM disc is in the drive?
> No.  At least not anything that I know about.
> 
> > If Linux knows that it will never have to perform any writes while
> > that disc is in the drive, can it speed anything up?
> Linux always assume that the disc is read-only with the exception[*] of
> UDF mounted disk(s).  UDF is a file-system used by CD-RW and DVD media.
> This dos *not* mean that all CD-RW and/or DVD out there are UDF as you
> can create ISO9660 file-system on those instead of UDF.
> 
> In general, if your system is configure correctly (which should be by
> default!) then your CD-ROM is functioning at the best speed possible.
> 
> > -- 
> > Stephen R. Laniel
> > steve at laniels.org
> > +(617) 308-5571
> > http://laniels.org/
> > 
> 
> 
>       * Technically, you could format a CD with (almost) any file-system
>         out there, however it will be hard and pointless to do so and
>         you will most likely lose more than what you'll gain from doing
>         it.  CD-RW, for example, have a limit on the number of writes
>         per sector (about 10,000 if I remember correctly), and that was
>         the primary reason for creating the UDF.  Don't think that
>         10,000 is a large number, whenever you read (or access) a file
>         the super block of the file-system have to be updated even if
>         you didn't change the file itself (that's to update the "atime"
>         or "access time") and hence you see why using "normal"
>         file-system on CD-ROMs is pointless.
> 
> Ziyad.
> 
> 

Hi,

I would be surprised if you couldn't increase performance on your drive.

For example, I noticed that hdparm was set to 0 on my cdrom. I suggest
you take a look at the man page for hdparm and see if your using dma.

If not, you might find an increase in speed by setting the using-dma (-
d) flag to 1. You can try it both ways.





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