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(Updated)
Overview
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Since my last article about writing CD's in FreeBSD, I experimented more with the
concept, and therefore I devised a better, and more stable way of writing them with the burncd command.
By following my own set of instructions, I encountered problems with
burncd. Sometimes, writing large images (say, around 600mb) the IDE bus would timeout, and reset, thus interuppting any burning in progress.
My other problem was the lack of buffering burncd used when reading the image for
burning - any amount of hard drive activity would easily interupt the read process, and cause a buffer underrun. For instance, opening a manpage would suffice to create a buffer underrun in the current
situation.
Solution
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As this document is an extension to my previous one, which explains how to set up
your cd writer to be supported by freebsd, I will assume you have read that, and have your burner set up, as well as knowing how to dump/create an iso image.
To be able to create a sufficient buffer, you need to install the team utility from
the ports collection.
# cd /usr/ports/misc/team/
# make && make install
Once completed, type my revised burncd command:
# cat /usr/misc/image.iso | team 100k 8 | burncd -f /dev/acd1c -s 2 data /dev/stdin
fixate
Don't forget to exchange the settings for drive, where -s is the speed, and -f is
the device.
What this command does is concatenates the contents of image.iso to the standard
output, team then arranges it into 8 guy processes, each caching 100k buffers, which stream this to standard output. Burncd then reads this continuous dump from the standard in.
Some of the output from burncd might be concerning, such as the wild percentage
complete estimate, and the 0KB file input (as it is reading from a character device).
You should see something along the lines of:
next writeable LBA 0
writing from file /dev/stdin size 0 KB
641474 kilobytes, 2141 seconds64079600%) total 640796 KB
written this track 641474 KB (64147400%) total 641474 KB
fixating CD, please wait..
Of course, the numbers vary on the size of your image.
This should now be a more practical way of burning and creating your CDs in freeBSD.
Final Notes
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o I managed to test out the buffering, by allowing cron to execute its daily tasks
halfway through my cd burning procedure. This **definitely** wouldn't have survived with the normal burncd command.
o This only applies to freeBSD 4.0 or later.
o Please give me some feedback on how you progress with burncd.
o I hope to write another doc soon on how to do disc to disc copies.
Good luck!
Andy Smith
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