Re: [OT] DVD read maximum at 3.5x, is this normal?

Hi,

> I am actually pretty surprised my IDE-wired DVD writer can only reach
> avarage of 4MBytes/s when I try to make iso file out of my DVDs by using
> 'dd' (tried various block sizes and settled down with 20480bytes which seems
> to be fastest for me). 

4 MB/s is indeed a bit slow. With DVD+RW and an older DVD-ROM drive
i get about the same speed at the beginning. But it then accelerates
to reach an average speed of 6 MB/s in total.
Younger DVD drives should read at 8 to 10 MB/s at least.
E.g. with DVD-R:
  4591878144 bytes (4.6 GB) copied, 382.137 s, 12.0 MB/s


> And, it takes 100% system resource to do that.

Can it be there is no DMA enabled with the drive ?

What do you get from this command (as supersuser):
  hdparm -d /dev/...

My system repplies
  /dev/hda:
    using_dma    =  1 (on)

I am not sure how hdparm plays with the new ATA driver that maps IDE
drives to /dev/srX rather than /dev/hdX. You will have to try.

If it replies
    using_dma    =  0 (off)
then try to enable it by

  hdparm -d1 /dev/...

After having started to read, check again whether it is still enabled.
If not, then the driver experienced errors and disabled DMA.


> I hope I can get a 10min/change or 5min/change frequency so I can do
> the job in half a day. Is it possible?

Plug in an external DVD drive and read two DVDs simultaneously.
One drive IDE and one drive USB should work in parallel quite
undisturbed.


Have a nice day :)

Thomas


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