Re: Low burning speed
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%
So not a single SYNC CACHE? ... Moving on to next probable suspect, unit
lying about available buffer capacity. Open growisofs_mmc.cpp in text
editor, locate lines that read
if (msecs>=0)
{ poll (NULL,0,msecs);
continue;
}
(line #637 in 7.1) and modify it as following:
if (msecs>=0)
{ fprintf(stderr,"--- %d %d %d\n",msecs,bsize,bfree);
poll (NULL,0,msecs);
continue;
}
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.
Well, not necessarily. In growisofs case when unit returns "long write
in progress", it takes a nap for estimated time to drain buffer to 1/2
of its capacity. Then it should be noted that UBU value is *minimum*
observed value for progress indicator update period. So that *if* unit
returns "long write in progress" a lot, it would be normal to observe
UBU lying around 50%. If not below, because system timer doesn't provide
enough accuracy to nail 50% mark exactly. Note that I'm only saying that
UBU values below 50% do not *necessarily* indicate a problem! I'm *not*
saying that it's not a problem indication in *this* case:-)
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 usually happens when recording crosses the velocity zone boundary.
Though it's too early if one trusts write performance descriptor [in one
previous posts it was at 112640*2K=230686720]...
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
again.
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 ?
Also, in case it's not executed as root, try to execute growisofs as root.
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
Or simply 'growisofs -Z /dev/dvd=/dev/zero'. This will guarantee that
there is no interference from file system. A.
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