Backing up a DV movie?

February 24, 2006 11:32 PM

I'm finishing up postproduction on a small digital video movie. I want to get a DLT tape storage system to back it up and send it off. However, I want to also use the same machine on my PC.

I edited the movie on two macs, one with OS X and the other with OS 9.2. I also have a windows XP machine that i use for print design and personal stuff. I want to use DLT because I've read that DVD duplication businesses prefer DLT tapes to other media formats. What kind of machine should I get and what should I be aware of when backing all of this up?

posted by clockworkjoe to computers & internet (8 comments total)

Most DLT machines are built around SCSI interfaces, but there are a couple of generations of DLT technology around now, and what you choose will depend to some extent on what you are willing to spend.

Early DLT decks were 10/20 GB or 15/30 GB capacity (the numbers being uncompressed/compressed data capacity, using on board streaming data compression). These drives were generally equipped with conventional 8 bit "narrow" SCSI interfaces, good for about 1.5 mb/second backup speeds. These decks use older media like DLT III, and can't take advantage of higher capacity tapes like DLT IV. The slow interfaces mean it can take quite awhile to put down and verify something like a 4 GB video file, but refurbished decks are available for as little as $100, and you can use cheap narrow SCSI PCI adapters to interface. Windows XP and Mac OS X should support these devices natively.

Later versions of DLT (sometimes called DLT4000 and DLT7000) came in 20/40 and 35/70 capacities. The higher data capacities also warranted faster SCSI interfaces, and faster tape transports, so these devices are generally equipped with 5 mb/sec SCSI II (16 bit or "wide" SCSI) interfaces. Later units may even have had Ultra 3 SCSI interfaces (10 mb/sec LVD or "68 pin" SCSI). Refurbished versions are generally available in the range of from $500 to $1500, and you'll need the appropriate level of SCSI interface cards and cables to get them to work.

Even later versions of the DLT technology are available, such as Super DLT (SDLT), with capacities in the 80/160 and 160/320 ranges. But these are high speed server backup subsystems, and will cost several thousand dollars per deck, and require U320 SCSI or FibreChannel interfaces.

If transfer speeds aren't all that important to you, you might get away with a used external DLT 4000 drive, and a narrow SCSI card for each machine. If you want 5 mb/sec transfer, move up to a DLT 7000 external machine, and Ultra 3 SCSI cards and cables for your computers.
posted by paulsc at 1:47 AM on February 25, 2006

You should be able to get a SCSI DLT drive to plug straight into your system. Obviously you will need a SCSI card to match if you don't already have at least an ultra-wide interface. Just talk to your duplication people and ask them what they prefer; DDS is pretty common and they may want that.
posted by polyglot at 1:49 AM on February 25, 2006

I want to get a DLT tape storage system to back it up and send it off.

This line makes me think you're not up to speed on the DVD production process, so:

1) When you send a movie off to get replicated, the file you deliver is not a backup but a disc image.

2) This disc image is created by authoring software and it's built not from your source files, but from compressed audio (ac3) and video (MPEG2) files in accordance with the DVD Spec (although you can use uncompressed audio - it just takes up a bit more room).

3) This is what C & A (Compression & Authoring) companies do. They all have DLT drives.


If you wanted to do it yourself, you'd need a good MPEG encoder like Cinemacraft SP to compress your video, and authoring software like DVD Studio Pro to create the disc image (DVD SP also includes an ac3 encoder and an MPEG encoder, but I can't speak for the quality of the encoded MPEG) . DLT 4000 drives are fine for replicators.

apologies if I've jumped to the wrong conclusion.
posted by forallmankind at 8:52 AM on February 25, 2006

I understand the tape will be a disc image. I want to do both though. Back my computer up AND send a disc image off. Is there some way around installing a SCSI card on every machine?
posted by clockworkjoe at 2:17 PM on February 25, 2006

Most DVD replication house will take stuff off of DVD-Rs nowadays (it used to be DLT only, then DVD Masters (a pioneer 101-a)).

Ask the replication house. A DLT is only necessary nowadays if you're going to make a DVD-9.

Nobody has come out with a firewire DLT (although several have announced it.)

Realistically, a scsi card per machine should be $100 or so each.

Alternatively, buy some hard drives for long term access.
posted by filmgeek at 2:37 PM on February 25, 2006

As for avoiding getting SCSI cards for each machine, if you have enough disk space in one machine to set up a network share that can be used as a backup target by the other machines, you could do that. Then, set up the other machines to do disk images to that share, and after the disk images are put there, have the host machine write them out to tape, for offliine archiving and backup copy physical dispersal. For a few hundred bucks, you could even add a dedicated hard drive to the one machine to establish a big dedicated network share, and tape copy target. This is frequently done in small server environments, and is all driven by scripts, which automatically save several generations of backup (depending on available disk space), and then automatically overwrite it.
posted by paulsc at 3:12 PM on February 25, 2006

So a new external hard drive is a better backup solution than DLT? Do you have any links about accepting DVD-R instead of DLT tapes? Thanks for the advice too.
posted by clockworkjoe at 4:13 PM on February 25, 2006

From Jim Taylor's DVD FAQ:

"It's possible to submit DVD-R(A) and DVD-R(G) discs for replication, with limitations. First, not all replicators will accept submissions on DVD-R. Second, there can be problems with compatibility and data loss when using DVD-R, so it's best to generate a checksum that the replicator can verify. Third, DVD-R does not directly support CSS, regions, and Macrovision. Support for this is being added to DVD-R(A) with the cutting master format (CMF), which stores DDP information in the control area, but it will take a while before many authoring software programs and replicators support CMF."

So if I were you, I'd approach submitting DVD-Rs for replication with a degree of caution.
posted by forallmankind at 4:37 PM on February 25, 2006