In article <[EMAIL PROTECTED]
.com>, Lars Strobor <[EMAIL PROTECTED]> writes
>Hello,
>I am interested in putting together a machine to burn lots of CD-ROM's for
>software distribution. I want to put anywhere from 5 to 10, 8 speed
>burners in the system that will write one ISO image at the same time using
>multiple processes of cdrecord. My question is will the SCSI subsystem on
>Linux handle this, and has anyone ever tried this? I understand that
>pre 2.2 kernels had problems with limited buffers in the SCSI generic
>driver. Will newer kernels have the same limitations? Any help or insight
>would be greatly appreciated.
I've done it (built three of them), and it does work. However, I had to
split the writers across more than one bus, to ensure sufficient
capacity. I could handle 5 Plextor/Yamaha 4x writers, using two Advansys
ABP-940U cards; I had to make a small patch to the kernel to provide two
instances of SG_BIG_BUFF, one for each host adaptor. (This isn't
necessary on later 2.2 kernels but is needed for early 2.2 and 2.0
series). The machine was a Cyrix 166, 32Mb ram, burning from an IDE HD.
The only other thing I found was necessary was to include some code to
detect the space available in the drive's buffer and use that as the
basis for sleeping or calling sched_yield in order to ensure some form
of balancing across the processes. I'm aware that this solution has come
in for saome flak, but it worked. There's some (now out-of-date) info on
what I did at http://www.azuli.co.uk/cdr_issues.html --I now have
another job, and the actual system as used by my client is now somewhat
more advanced than the software on that website. If you email me I'll
try to gather together more up-to-date information for you (but I'm
frantically busy at present)
I'm trying now to implement a solution based around cdrdao instead, to
save the hassles of parsing the structure of the original disc...
John
--
John Gray | [EMAIL PROTECTED] 0121 688 8897
Azuli IT Services, Birmingham | Web, databases, custom Linux solutions
www.azuli.co.uk
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