DVD burner farm

[Lennart Sorensen]

On Tue, Jan 25, 2005 at 10:54:44PM -0500, jim ruxton wrote:
> I'm looking at putting together a system that will burn 50
> DVDs at a time. I'd like to use 16x Burners such as the Pioneer
> http://www.pioneeraus.com.au/computer/dvdwriters/dvr108/ I would like to
> be able to send the DVD burner farm an iso image via a network
> connection or firewire perhaps. Of course I'd like the system to be
> Linux based but can't be too fussy. I've seen duplicators like this
> around http://www.americal.com/pg/pioneer-16x-dvd-duplicators.html#nine
> however as far as I can tell they all need to have a source DVD first.
> Has anyone got any thoughts on this? How do the big guys do it?

I saw one system a few years ago (using Win NT 4 on the host) that had 4
SCSI plextor writers, and a SCSI robotic for loading the CDs from a
spindle into the drives, and it had it's own software that would write
to the drives when they were ready and verify discs and such.  It also
had a B/W CD printer that it ran the CD through after it was verified,
and would print cross hatches on the CD if it was a coaster.  Seemed
pretty neat, but proprietary.

On Linux you could certainly (given enough IO bandwidth, or enough ram
to cache the image to write) handle writing to multiple drives at once
(if IDE, don't let them share the same controller cable, or you may have
problems, but then again maybe you won't).  50 seems like an awful lot
to do at once if you don't have an automatic way to load the discs.  You
could barely keep up changing discs by hand in the time a 16x drive
writes discs.  You probably couldn't keep up.  And how are they going to
be labeled?  Epson has some nice CD/DVD capable printers (R200, R300,
etc) that make nice looking discs.

Now if you had a very large case, I wonder if you could run 12 SATA
plextor writers from a 3ware controller card.  That would be pretty
neat.  I still suspect bandwidth would be an issue.

16x1.3MB/s = 25MB/s (to get a nice round number and allow for some
overhead).

PCI bus = 132MB/s (theoretically).  66MHz 64bit PCI = 500MB/s.

So if you had a 64bit 66MHz PCI server to run it, you could potentially
run 12 drives of a controller and not saturate the bus.

Most of the dedicated duplication systems have custom hardware that
simply reads from the source drive and writes to all the other drives at
the same time on separate channels.  They are designed for it and don't
have the limitations of a standard bus (and most of them probably use
slower drives still).

Oh well, enough babbling from me.

Lennart Sorensen
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