Disc Duplicator

Currently, this topic contains my research into Disc Duplication. I have two different pieces of hardware that have prompted this. The first is an actual CD duplication device, it makes use of a robotic arm to load and unload CDs from its two drives. I have refitted it with a new motherboard and two CD/DVD burners, however the scripts I wrote to automate cdrecord have been less than perfect. The second is a 7-disc SCSI CD-ROM tower that was given to me. I'd like to see what it would take to convert it to a CD/DVD burning device.

The software

My experience with the automated duplicator led me to RedHat^?'s Fedora Core operating system. I chose it over other GNU/Linux distributions because the included version of cdrecord was patched to handle DVDs as well.

Software for the robot

Currently the robotic duplicator is running a series of custom shell scripts to handle the duplication. I would like to find a more robust solution, however the arm control is propritary and there is very little (no?) demand for OSS to drive such a device.

Software for the tower

The tower does not have the same software challanges as the robotic duplicator. The TurboJet CD/DVD Duplicator project seems to cover everything I would need.

The hardware

The hardware can be a little trickier. Once again, the two duplicators have different needs. The tower needs an external bus of some sort, while the robotic duplicator needs a full PC that fits within its case.

Hardware for the robot

At the moment the hardware for the robotic duplicator is functioning perfectly. The only reason I might change it, would be to turn it into a peripheral for a PC, instead of the self-contained device it is now. If I were to do that, it would have virtually identical requirements as the tower.

Hardware for the tower

The tower has seven bays available. Unless any other devices are required to fit in any of the bays, seven drives would be required. Because of space and heat requirements the tower will most likely be a peripheral device, there just isn't room for a motherboard in addition to the drives. The biggest question is, what interface will the drives use? The CD-ROM drives installed in it make use of the SCSI bus, with a pair of SCSI connectors on the rear of the case. Whichever bus is chosen, it has to be fast enough to support one or more DVD burners at a reasonable speed. If it can only handle one or two drives (which is likely), it must be relatively cheap to install multiple interfaces on the PC.

Busses

USB bus

The first bus that came to my mind is USB. USB 2.0 Hi-speed ports can transfer data up to 480 Mbit/s or 60 MB/s, however they commonly only achieve 30 MB/s. The biggest draw of the USB bus is that it is cheap, USB ports are very common. There are also a number of USB to IDE (PATA) interfaces available, which is handy as IDE is the most common optical drive interface at the moment.

• http://en.wikipedia.org/wiki/USB

The IEE-1394 (Firewire) bus

According to the Wikipedia article on USB, real-world tests indicate that Firewire generally outperforms USB 2.0 for storage devices. The Firewire spec that competes with USB, S400, can transfer data at 393.216 Mbit/s, or 49.152MB/s per second. There is also a newer Firewire standard available which provides even higher data rates, but it is rather expensive. Unfortunately Firewire is not as popular as USB, its main competitor. The selection of Firewire devices and controllers is lower than with USB.

• http://en.wikipedia.org/wiki/FireWire

External SATA (eSATA)

The Serial ATA bus, or SATA, is much faster than USB or Firewire. It can achieve rates of up to 1.5 Gbit/s, however due to overhead the maximum data transfer rate is usually 1.2 Gbit/s (150 MB/s). This is much faster than USB or Firewire, and ideal speeds for DVD burning. Unfortunatly, eSATA cables are limited to a length of two meters.

• http://en.wikipedia.org/wiki/SATA

Parts

I put this list together based on what was in stock at http://www.newegg.com/ and assuming I wanted to convert my robotic duplicator to eSATA. I already have a dual port eSATA PCI adapter.

Newegg.com prices for required eSATA equipment

Product	Link	Price
eSATA to SATA converter /w eSATA cable	http://www.newegg.com/Product/Product.asp?Item=N82E16812240002	$26.99
Samsung SATA 18x DVD-/+RW /w Litescribe	http://www.newegg.com/Product/Product.asp?Item=N82E16827151141	$46.99
Molex to SATA power adapter 2ct	http://www.newegg.com/Product/Product.asp?Item=N82E16812105008	6.99

Note: The drive listed above does not include any cables, and only has SATA power connectors.

-- JasonHill - 11 Feb 2007