[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Low burning speed


Tomasz Kaptocz wrote:
>  181403648/4220336128 ( 4.3%) @6.0x, remaining 11:30 RBU  99.1% UBU  84.6%
>  209125376/4220336128 ( 5.0%) @6.0x, remaining 10:52 RBU 100.0% UBU  80.8%
>  232062976/4220336128 ( 5.5%) @5.0x, remaining 10:53 RBU 100.0% UBU  73.1%
>  241631232/4220336128 ( 5.7%) @2.1x, remaining 11:15 RBU  98.9% UBU  30.8%
>  256933888/4220336128 ( 6.1%) @3.3x, remaining 11:18 RBU 100.0% UBU  19.2%

The drive seems to be willing to run at the speed which
is announced for the first part of the media: 6.0x. 

The fact that the drive buffer (UBU) after a short time
of burning has less than 20 % fill indicates that there
is a problem with data transfer from computer to drive.

Effective throughput seems to be about 4.3 MB/second.

This incident here looks quite strange:

>  1882193920/4220336128 (44.6%) @3.7x, remaining 8:10 RBU 100.0% UBU  26.9%
>  1883176960/4220336128 (44.6%) @0.2x, remaining 8:13 RBU 100.0% UBU 100.0%
>  1883176960/4220336128 (44.6%) @0.0x, remaining 8:17 RBU 100.0% UBU 100.0%
>  1886191616/4220336128 (44.7%) @0.7x, remaining 8:21 RBU 100.0% UBU  15.4%

Drive buffer is reported as full, but there is no
substantial data transfer for a short time.
This cannot be blamed on a bad throughput.

Maybe the drive buffer ran empty and the drive
decided to wait until it is at 100 % again.
Then it needed some time to speed up disc rotation

Experiment proposal:

Would it work with better speed if you do not
burn the ISO image on the fly but first generate
it in a disk file and afterwards burn that file
to media ?
For simplicity you could omit the mkisofs run
and just create a dummy file of 4 GB:
  dd if=/dev/zero of=/tmp/4gb_of_zeros bs=1M count=4096

(1 GB = count=1024 should suffice too.)

This file could be burned to media by various programs:

  growisofs -use-the-force-luke -Z /dev/sr0=/tmp/4gb_of_zeros

  cdrecord -v dev=/dev/sr0 /tmp/4gb_of_zeros

  cdrskin -v dev=/dev/sr0 /tmp/4gb_of_zeros

Of course, the result will not be mountable but only
bear a lot of 0-bytes. One can verify success by
  diff /dev/sr0 /tmp/4gb_of_zeros
which might report surplus bytes on /dev/sr0.

Have a nice day :)


Reply to: