MiniDV As A Backup Medium 200
MiniDVfanatic writes "Last year I read an article in Slashdot about
using MiniDV as a backup medium.
Now I've found a recent article about the same topic in bulmalug.net. It's in Spanish, and it just talks about dvbackup, the same tool recommended in some old Slashdot posts, but it adds some interesting ideas such as data compression and interleaved Reed Solomon for error detection and correction, using a tool called rsbep.
According to the author's tests, this should let you backup 13GB in a cheap MiniDV tape in a safe manner, and restore it all later. Example commands provided, with simple workarounds for slow machines which cannot feed the tape at 3.6MB per second." You can fish the translation, for those who need - I was able to get by with my high school Spanish. Pretty cool stuff.
What about speed? (Score:5, Insightful)
Harddisks are really cheap these days, CD-Rs are also cheap and writable DVDs are becoming an option... Does it pay off?
Re:What about speed? (Score:5, Informative)
Re:What about speed? (Score:2)
A very good point. I would however dear to claim that there are probably cheap DV-tapes which could easily suffer the same fate as cheap CD-Rs.
Then again, I might be wrong
Re:What about speed? (Score:2)
Think about it.
Re:What about speed? (Score:2)
Also, why do you think a lot of early languages had line numbers?
With one line per card, if you dropped the deck you could just sort on the line numbers and get it back.
You'd be wrong :) (Score:3, Informative)
Re:What about speed? (Score:2)
Some tapes will cause digital-dropouts and worse almost instantly when used in certain cameras while work perfectly in others...
There seem to be a lack of quality in some tapes or there's some misunderstandings between some camera-makers and some tape-producers ;-).
miniDV consumer-grade, not data-safe format (Score:3, Informative)
Also, no DV formats are designed to be 100% bit safe. A lightweight video codec like DV can handle an off bit here and there without ruining the project. Just a little visual glitch here and there on a single frame, and pro decks do a good job of interpolating the missing data so the problem isn't too obvious. Not really possible with a compressed data bitstream.
Re:What about speed? (Score:2)
I have two Panasonic DV tapes recorded as recently as December of 2000 with dozens of missing frames caused by severe dropouts. It was one of only two on-tape copies of the master for said movie, and the only copy that's here in California.
Thankfully, when I made the copy of the original, I kept the files on a hard drive. The hard drive data, unlike the DV backup, is intact; the DV original, shot to hell.
Hopefully tapes by other vendors (TDK, Fuji, etc.) are more reliable, but even still, the thought of trusting any valuable data to be adequately backed up by mini-DV tapes makes me shudder.
Re:What about speed? (Score:2)
Tape strikes me as a redundancy plan for short term backup on a daily to weekly scale, however if you are going to expect something to last 'forever' other forms of storage may be better. You say that you've had CD-Rs fail, but have any failed that had the same ammount of use as the tape that you just dug out of the closet?
People mention DVD-Rs which as far as I have seen work fine as long as you don't handle them (scratches mame home dvd burns almost as fast as well.. something fast), and if you are meaning to do a real archival, I still believe that dropping a dollar per blank cd balances reliable long lasting media with decent capasity.
Anyway, most times people are storing way too much for archival... you don't need a full copy of your system in 10 years, you just need the documents and data. As a student I can back up the past three years and probably another 10 years of word docs onto a single CD-R with a redundant image on my school email server... that's a cheap and really sound backup solution.
What about hardware longevity? (Score:2)
Re:What about hardware longevity? (Score:2)
That being said, the prices of IDE-harddrives and raid-controllers like these [3ware.com], you might as well keep all your data online. That's a sure way not to let the media become outdated...
Re:What about hardware longevity? (Score:2, Insightful)
Re:What about speed? (Score:2, Insightful)
However, my experience with brand-name CD-RWs on a good quality drive has shown up nearly 100% reliability (only 1 bum disk) over 4 years. FWIW, of course...
Re:What about speed? (Score:2)
Magtapes are supposed to be at least that good; better, if you store them in the proverbial cool, dry place. Your real enemy is temperature fluctuation, as it will cause the media to expand and contract. You certainly don't want to get them too hot, though, or operate them too cold (though I doubt you could damage a magtape by getting it very cold, you would have to get it very, very cold...
Re:What about speed? (Score:2)
Re:What about speed? (Score:2)
On the other hand, I have videotapes from 5-10 years ago that are barely watchable anymore due to degradation. If an analog signal deteriorates so badly, can you imagine what would happen to the integrity of a digital bitstream?
I also have yet in several years of burning to encounter a CD-R that worked correctly at first, but later became unreadable.
Anecdotal evidence is not evidence.
Re:What about speed? (Score:2)
Re:What about speed? (Score:2)
This PDF spec [verbatim.com] on Verbatim's site throws out a figure of 100 years for General Use DVR-R discs. Another PDF I've seen on Pioneer's site says the same thing, but in reference to DVD-R for Authoring discs. We use the latter at the office since Pioneer suggested to us that the Authoring discs are better for archival purposes. The discs are probably 2-3 times the price of General Use discs, but for securing source code, etc. it's worth it.
Re:What about speed? (Score:2)
Re:What about speed? (Score:2)
The point was that the drives "scrub" the disk periodically when they're idle (or so I'm told). Spinning it up and doing a read of a few blocks just doesn't have the same effect, although it would at least minimize the stiction risk.
Now, a periodic "dd if=/dev/hda? of=/dev/null" is another story, and I'd expect that to be sufficient, but I'm not certain....
Re:What about speed? (Score:3, Interesting)
50/100 GB Tape: $50. Easily unmounted, removed, taken off-site or stored in a safe, etc. Tape changers make backing up to multiple tapes/rotating tapes a cinch. Random seek times for a particular file is slow, but full restores are acceptable.
Spare 100 GB Hard Drives: $100 If you go with cheaper IDE drives, you probably aren't going to do hot swapping, so you'll have to bring the system down to remove them. SCSI would be more expensive, but would allow hot swapping. NAS is an option though, but slower. Drives are not meant to be carted around, bumped, etc like removable media is. One accidental drop and the entire backup is shot unlike tape or disc based backups. Really fast seek times though.
CD-Rs: Cheap. $15+ depending on quality/name brand. You can get free at BestBuy or some place after rebate, but usually not worth the hassle for a business. Only holds 700 MB, so be prepared for lots of swapping. Slower then other methods. Plus you now have a stack of 150 CDs for every backup that you do. Can be transported around, but inconvenient. Fast seek times for individual restores.
DVD-Rs: More expensive then CD-Rs. 20+ for 20 disks for a 100 GB backup. Same things apply to CD-Rs, stack of discs, inconvenient transportation, etc...just less discs.
This is all hypothetical of course, you circumstance may be different.
Tape drives were not meant for backing up individual files for restoring those individual files. It was meant for archiving large data file/sets. Tapes offer a large capacity at a decent price with convenience of having all your data in a small durable package unlike what hard drives. Yes there are going to be alternate storage mediums, but there is a convenience/price/durability tradeoffs.
If you want to be able to seek to a particular file to restore/modify it, go with a CD-R or HD. If you want to backup your system, go with tape.
Re:What about speed? (Score:2)
Well this used to be the case.
Today there are several makers that supply IDE-RAID card that support hot- and coldswapping.
You can also get drivecages that are suspended from the cabinet so the whole thing can handle transportation without being damaged. ;-)
I even heard a story of somebody having a disk-storage box returned because of damage to the chassis (the sidedoor was cracked in transport) but the disks survived like a charm
Re:What about speed? (Score:2)
Everything adds up extra. I said later down that there were other storage options. Like you pointed out, there are even with actual hard drive. Although adding a IDE hotswap controller and shockmounted drives are going to add significantly to the price...possibly 400-500% over the price of just the drive.
Re:What about speed? (Score:2)
Each of them drives is gonna set you back ~$200 (easy number) so for $3200 you've got a ~2.5 Tera RAID system... That's pretty cheap considering this is ONLINE data, not offline-backups...
Buying more disks would offcourse allow you to hotswap and store the disks both offline and offsite, making it a viable backup solution as it takes 200 gigs per medium, and it's fast to backup to and not at least restore from!
Re:What about speed? (Score:2)
First of all, the solution to your hot-swapping problem is firewire. You can get an adapter to stick an IDE drive on a 1394 bus. Second of all, hard drives ARE designed to be carried around, this is why the heads park. While the heads are parked it's actually pretty hard to damage a hard drive without dropping it pretty far onto a hard surface, though your mileage may vary on this point.
Get a IEEE1394 enclosure with a 5.25" drive bay in it, get an IDE hot swap adapter, and hook it all up. When you want to change drives, pull it off the 1394 bus, power down, and swap. All the benefits of SCSI that are relevant here, and none of the disadvantages.
What about ATAPI? (Score:2)
I like your post, but you forgot that modern EIDE disks support tunneling the data through another transport. So an ATA hard drive solution does _not_ mandate using an ATA adapter with 2 devices per IRQ in Master/Slave. You can mount an ATA disk using many other kinds of buses and gain hotswappability in the process. ATA bridges for USB, 1394/Firewire, SCSI, and even the parallel port exist and can be bought at Fry's. There are disadvantages, like USB's bad speed and reputation for unreliability, or Firewire's cost, or SCSI's device conflicts. But it can be done.
I _think_ SATA also supports hot-swapping drives, and there's a standard in the works for using USB for internal peripherals.
The big downside to ATA drives is storage. Even though head autopark now, they're still more vulnerable to crashes when spun-down. And if a drive mechanism is going to fail, the spin-up after the drive's been in your file cabinet for a year is when its going to happen, maybe due to a little stiction.
Re:What about speed? (Score:3, Interesting)
Hard drives ARE a good medium for backups. Sure, they weigh more, so can't take as much of a drop, but tapes don't have metal casing around them, so hard drives are less vulnerable to electrical/magnetic interference. You could have sheilded cases for tapes, but they are vulnerable while you are handling them. So you really have to choose your poison in that case. Any story of restoring ancient backups always includes the part about all the tapes that just couldn't be read ofter years of sitting in storage closets. Admitedly, that's often due to over-use of the tape, but hard drives are clearly more durable for repeated uses.
In addition, tapes cost about the same as hard drives for similar capacity, and yet hard drives don't require extra hardware that will set you back several thousands of dollars, so HD are clearly cheaper for the smaller shops.
In addition, when you spend thousands for your 100GB tape drive, you are stuck. You can't use the 250GB tapes that come out the next year, until you spend several more thousands of dollars for the new drive. Not to mention that hard drives can all be used simultaneously, while you can only use one tape at a time per the number of multi-thousand dollar tape drives you have.
Re:What about speed? (Score:2)
For about the same $$, you can get a nice DDS4 DAT drive, which does 20/40GB, and has super-cheap tapes - $17/ea at CDW, probably cheaper elsewhere..
Sourceforge has one for OS X (Score:5, Informative)
It works very well. 5 gigs on a tape, 10 if you don't make it redundant.
Re:Sourceforge has one for OS X (Score:3, Interesting)
Re:Sourceforge has one for OS X (Score:2)
For OS X? The SourceForge page says "Linux", and the dvbackup page makes no mention of anything except "Unix". I just downloaded and it built OK on RH 8.0.
Firewire isn't available under Linux (AFAIK) with my Asus A7N8X MB (NFORCE2), and I don't yet have an appropriate camcorder anyhow. I may have to get one to check this out. ;-)
At any rate thanks for the interesting link!
Re:Sourceforge has one for OS X (Score:2)
they open standard: if your to streamer, aah to camcorder dies you dog rescue your dates with any to other one (except PAL/NTSC need to fit), you plows not bound to to special company
it's to faster streamers than many and it will be dwells comfortable - you dog uses the search-index function to "jump" to to recording
Wha? The incessant use of the word "dog" was driving me nuts, bringing up memories of that Sean Connery movie from a couple years back. Anyway, back to your regularly scheduled broadcast, dog!
Ive seen this before... (Score:5, Interesting)
Re:Ive seen this before... (Score:4, Interesting)
Nowadays most ADAT recorders are HD-based though, but the format's popularity was largely due to the cheap media, when compared to other digital multichannel systems at the time.
Re:Ive seen this before... (Score:4, Informative)
Here's a few links:
http://www.pwr.wroc.pl/AMIGA/AR/ar410_Sections/re
http://www.amiga-hardware.com/vbs.html [amiga-hardware.com]
http://www.aurora1.demon.co.uk/gadgets/vbs.html">
Re:Ive seen this before... (Score:2)
Try about 15 years ago. I bought one of these things with the assurance that it would work with my old betamax recorder, which it didn't. No point sacrificing a VCR that you're still actually using..
I'll never like tape backup (Score:2, Insightful)
The reason this is a great idea ... (Score:2)
Further you could include the transitions and extra audio to change it.
Plus, any multi use is a good use, especially if it were unexpected.
Recently the Mac Community has seen two very cool apps for Sony T68i phones. They remote control the DVD Player and iTunes + Powerpoint presentations. Sure, there's other remotes that do a better job, but it's still handy. You always have your phone. Just as, some people always have their camcorder and PC nearby.
I have a digital camera that has an MP3 player built in, it's practically useless, except for the sound effects that I keep on there, in Mp3 format, to add to slideshows. I can edit on other people's computers when travelling.
Backup Shelf Life (Score:4, Informative)
Re:Backup Shelf Life (Score:2)
Interesting. Do you happen to know if DVD-R (or DVD+R) is similar?
I have a rather keen interest in the answer to this, as whilst typing this in the background Pinnacle Studio is hard at work preparing a DVD image of my wedding video shot on Saturday...
Cheers,
Ian
Re:Backup Shelf Life (Score:2, Insightful)
I suggest that you burn two DVDs and keep each at a separate location (one at work, one at home for eg). Reburn one (or both, if you want) of them every two or three years.
I expect my CDs to last up to 10 years, but like I said, they're mere backups that live in a CD folder and are rarely touched. You're talking about your wedding, not ancient pr0n/mp3 archives.
Re:Backup Shelf Life (Score:2)
Good advice, and advice I'll take.
I also have the advantage that I run a small-scale webhosting operation. If I copy the DVD image to my server, it will be both an offsite backup and copied to tape by my co-lo hosts on a nightly basis. Paranoid certainly, but as you point out we're talking about data that is crucial to me.
Cheers,
Ian
Re:Backup Shelf Life (Score:2)
Professionals in the industry generally know better than to use MiniDV for broadcast-quality recording. Also, the people who made CD-Rs in the beginning claimed a 20+ year shelf life, and nobody should believe them. Nobody seriously claims a data life for a consumer quality videotape, because they're not sold or tested for data-grade applications, but for videotaping, and consumer videotape has a really high "acceptable" loss rate.
Re:Backup Shelf Life (Score:2)
Oh, you'll also want to let the journals know they shouldn't be making claims about the use of DV as a long term storage for high quality masters. I mean, they'll be so embarassed when they realize their mistake, but relieved that you set them straight.
Re:Backup Shelf Life (Score:2)
MiniDV is a lot different, and it's got to do with the quality of the tape used, which is exactly the part of the system we'd be using for data storage.
Try looking here [spec-comm.com] for a precis by a company that maintains/repairs hardware for both types of systems, or here [sonyusadvcam.com] if you want a manufacturer's perspective.
They're not the same. One has much better performance and stability. It's not the consumer grade.
How much data do you have? (Score:2)
Re:I'll never like tape backup (Score:3, Informative)
great! please tell me how to back up to CD or DVD 90 gigabytes of data daily. or better yet the 1.2 Terabyte SQL database I have or how about the 20 terabytes of video files the master video database has here...
CD and DVD is only a really small scale backup solution for low end home use or special use. Cd and DVD is for content authoring first and foremost.
Hell it takes 20 CD's to backup my documents directory her at work.. That all the policy and proceedure manuals, company built software manuals, and other documentation.
I love tape backup and until someone creates a backup solution that is greater than DLT with the same reliability it is the absolutely the ONLY choice in backups that matter.
Take it easy... (Score:2)
Dude, that is a LOT of porn.
If you're a masochist, then yes... (Score:2, Interesting)
Sorry, but for starters, you can't fit 200GB onto a DVD-R. Secondly, I can back-up 200GB to an AIT tape in right around 3 hours. You just can't do that with optical media right now. Not to mention that AIT drives can be found pretty cheap these days if you don't HAVE to have an AIT 3 drive.
This is why I'll never like optical backup right now. It just can't compete with my AIT drive. I buy archival optical media for long term storage of data, but the workhorse of my back-up efforts for giving me the security of knowing that *everything* is getting backed up every night... I don't know how I could live without AIT.
don't bother (Score:3, Insightful)
With IDE drives down to around $1/G, just go out and buy yourself a bunch of IDE drives for backup--they are a lot more reliable and a lot faster. Or, get a DVD-R: at 4.7G per side, it's not so different from a MiniDV, and they are bound to last longer than a MiniDV backup tape.
Re:don't bother (Score:2)
What about when your house burns down, your power supply drops 120VAC on the +5 line of all of the drives, etc? Am I supposed to drop an IDE disk in my safety deposit box occasionally? As far as DVD-R goes, so far the media cost seems kind of high to be running full backups very often. (E.g. nightly, which is easy to do with tape.)
Note, I'm not endorsing the idea of using video tapes for backup, but using a real tape backup still seems like the best option to me for data you really want to be able to restore.
Re:don't bother (Score:2)
I would certainly hope that you would store your tapes off-site, why not your backup HDs?
I had nothing but failures on the old (admittedly consumer-grade) tapes I used to use. I back up my personal data to CD now. I really should get better about putting it in the firesafe, though (I think my currents are in my CD binder...on my desk)
A warning about CD-R backups: I've had CD-Rs fail. This was 7 years ago, but we had some gold-colored discs develop "spots" on the written surface, under the plastic. They made the files generally unrecoverable. The degradation occured in a one year timespan. After that, we kicked around the idea of redundant backups and test-reading our old discs once per month just to make sure we didn't lose anything again. Of course, back then our entire department generated only about 150MB of new data each year.
Re:don't bother (Score:2)
Yes. If the size bothers you, pay a little more and get laptop drive or a bus-powered USB2 drive. There are about half the size of a VHS cassette.
Or, alternatively, simplify your life, stick the disk into an old computer and do backups over the network (the link doesn't have to be very fast). You can do wireless and put it somewhere reasonably far away from the main computer (garage?), put it at a friend's house, or colocate.
As far as DVD-R goes, so far the media cost seems kind of high to be running full backups very often.
Media are down to under $2 per disk for both "R" and "RW" (2-3x that at your local CompUSA). You can use DVD-RW if you want to reuse backups.
Re:don't bother (Score:3, Informative)
Yeah, tape doesn't last very long..... I'll go tell these tapes we use and rely on that.
Re:don't bother (Score:2)
Yeah, right. And if it doesn't last 50 years, the manufacturer will gladly replace the media for you, which is the degree of their liability. And DLT's are at least designed for data and backups, MiniDV are consumer media for video. Get the difference?
and we have some 9 track magnetic tapes we found in the basement from the late 70's along with a 9 track tape reader that had an ISA card from the mid 80's and dos drivers (on a 5 1/4 inch floppy) to read that tape last week... it read fine..
I have had 8mm and DAT tapes fail after a few months. Tapes develop a lot of cross-talk between loops if they sit around for too long (you can hear it on audio). The coating used for tapes becomes brittle and just falls off sooner or later.
Yes, you can get lucky. And 9 track tapes are probably the most robust given that the data density is so low. But it's not something I would trust important backup data to.
Re:don't bother (Score:2)
Clearly there are two different almost religious views on this, but many of us have been burned by tape backups too many times to keep putting blind faith in them.
Re:don't bother (Score:2)
No errors. one tape rotated in every 6 months to rotate out one full backup.
Never had a failure, and tests on tapes that had an excess of 1000 read/writes at a lab showed no significant degradation.
tape = excellent.... espically prefessional level stuff called DLT.
Lumpy is right, DLT is bulletproof, that is why 95% of all enterprise level companies use it exclusively for critical data.
apples and oranges (Score:2)
And for the privilege of using a sequential access storage medium, you end up paying more per gigabyte than if you just bought an IDE derive.
All of that fiddling with DLT may still make sense for enterprises, but it makes no sense for someone considering using MiniDV for backups.
Re:don't bother (Score:2)
On the other hand, you're thinking about analog signals stored on magnetic tape. Digital signals aren't anywhere near as delicate as analog waveforms (since they can take degredation and still be perfectly readable), so they'll last much longer longer than those VHS tapes you're thinking of (especially the ones you recorded at EP speed).
Re:don't bother (Score:2)
The actual software projects used: (Score:4, Informative)
and dvbackup [sourceforge.net]
Using them is relatively straightforward. Actually, it looks like rspep is a generic implementation of reed solomon error correction, which would make it usefull to storing information on any somewhat lossy or error-prone media.
Cost effective? (Score:5, Informative)
You can pick up a DDS-3/4 DAT drive on eBay for under $300. Tapes come in at similar costs to MiniDV (or cheaper). These will backup more than the DV tape and are designed for this sort of use. MiniDV cameras however cost more than this and aren't designed for this sort of use.
The only reason that I can see for looking at this at all is if people have a MiniDV tape and want to make occasional backups. It could be a risky business for though for two reasons:
I remember using the first 8mm backup systems, derived from 8mm video mechs. They were notorious for only being able to restore on the same mech. This would have been fine if the failure rate of the mechs wasn't so high.
Re:Cost effective? (Score:2, Interesting)
Re:Cost effective? (Score:5, Interesting)
It was designed to be connected to a computer, accepting bi-directional communications with error correction, with a tiny tape that stores up to 1 hour of DV quality (essentially lossless) video, or about 14Gbs.
If it is already there, if it is already connected to the computer through an extremely fast interface, and if it is so easy to backup data, then what is the problem with backing up your data? That they have a high mechanical failure rate? And what is your proof? 8mm backup tapes?
This is not intended to replace DATs at the server room, it is just to extend the use of something you already have. This is hacking at its best.
The only thing that does not excite me is that the tools are not 100% compatible with Windows. Yes, I can compile them with gcc but I want my dialog boxes dammit! :-)
Re:Cost effective? (Score:3, Informative)
This is not quite true. DV is MJPEG, so each fram is compressed lossily, but there are no intermediate frames constructed just from changes applied to previous frames. This makes it very good for video editing, since each frame can be edited without affecting any other frame, but it is not lossless.
"essentially" lossless (Score:2)
i.e. the compressionr ratio is so low that it's uncompressed for all practical purposes.
Just like it's practically impossible to tell the difference between an SHQ 2048x1536 JPEG from my Olympus C-3000 and a TIFF from the same camera. SHQ JPEGs from that camera equate to using a quality level of 98% or 99% when saving using GIMP or ImageMagick filesize-wise. (Default seems to be 80% or 90% - Even at those quality levels it's hard to see a difference.)
Re:"essentially" lossless (Score:3, Interesting)
Re:Cost effective? (Score:2)
Also, what I said is that it is essentially lossless. I dare you to find artifacts on any dv movie filmed with a reasonably modern DV camera.
Re:Cost effective? (Score:2)
Okay. While strictly true, DV is DCT based, and so I lumped it in the same category as MJPEG. I could have spent a page explaining the differences, but I didn't bother because they both use more or less the same algorithms, and I doubt anyone would bother to read it if I did.
I dare you to find artifacts on any dv movie filmed with a reasonably modern DV camera.
Sure. Film a white background with a black line in the middle. Oh look, on either side of the line there is a hatchy gradient. Why? Because DCT based algorithms can't cope with this kind of source image, which I think was the point I made in my last post...
Re:Cost effective? (Score:2)
We get artifects such as that on our professional DVCAM camera, while the pass through (using Y/C out) is nice and sharp.
The little MiniDV jobby we have smears before it hatches on fine detail or deliberate attempts to show up the limitations of the format.
No doubt the DVCAM has an added advantage since the track pitch of the tape is 1.5x wider than DV, although this reduces the recording time by a third.
Re:Cost effective? (Score:2)
Re:Cost effective? (Score:2)
I don't see an issue with using your camera for occasional backups, it's your camera :) I was pointing out there are cheap solutions to this issue that may be more suitable.
WRT mechanical failure. I have no proof for miniDV. Apply a little bit of logic though. The mech in a consumer level device is primarily designed for record and playback on a streaming basis. Backup tends to be like this, restore less so. If you are using your device for regular backups you are likely to use it more than just as a video device. This will wear everything more. The more you use it the more chance of it failing.
Back in the early 90s video 8 was released. At the same time this was seen as a more cost effective medium for backups than QIC (Quarter Inch Cartridge) tapes and so a modified version of this mech was used for data backup. The problem was that the tolerances for data and video are different and the drives had problems with alignment. This led to problems reading tapes written on one drive not being readable on other drives. It could be the same model from the same manufacturer but it just wouldn't read. Once DAT became more widely available 8mm lingered on a while (it had higher capacity) but was gradually replaced.
Why isn't the opposite done? (Score:2)
Now imagine a DDS-based camcorder, with a built-in mpeg4 encoder. It would fit in the palm of your hand, and be able to record 50 hours of video in one tape which is about half the size of a DV. That would be possible with current technology, using OEM parts that are available right now.
Preventing data loss using striping (Score:4, Interesting)
Re:Preventing data loss using striping (Score:2, Informative)
It mixes up large blocks of data and then does ECC on them, so if a large block gets dropped due to an error, it actually contains a small number of bytes from many other block, each protected by a separate ECC.
This is the same type of error correction used on CD's (CDROMs uses 3 layers of ECC).
It's an interesting poing, though (Score:3, Interesting)
I remember there was people who made "VCR backup solutions," too. Anybody knows what happened to them?
before anybody gets too negative, remember I am talking 10X redundancy for 15G. Heck it's sure a lot cheaper than DVD-RW right now, so from price/GB point of view, I think it still kicks DVD's butt, even if higher redundancy was needed.
Re:It's an interesting poing, though (Score:3, Interesting)
First off, a DVD is 9.4G/side - most current DVDs are dual-layer. Rewritable DVD's are still only single layer.
Next, you've deeply, vastly, absurdly overestimated the quality of VHS. Record at best quality possible on VHS and it's still less than half the line count of DVD, and we won't even go into chroma and lumiscence loss.
The one estimate I've seen for VHS backups is 2.7GB... certainly not that bad, but it has all the drawbacks of tape storage and requires a rather hokey control system (IR blaster out of the PC).
Re:It's an interesting poing, though (Score:2)
VHS can hold approx. 50 gigs now (Score:3, Informative)
I'm talking about D-VHS. (Such as the JVC HM-D30000U, and 1-2 other DVHS decks in existence.) These are designed from the ground up to record digitally, and given the bitrates specified and the recording times, it comes out to something like 40-50 gigs per DVHS tape. Not sure how well "standard" VHS tapes work, they're probably exactly the same except for a cost premium for the DHVS-specific tapes.
Current limitations:
a) DVHS decks record MPEG-2 transport streams, not DV video streams. Which means dvbackup won't work. DVHStool for Windows is about halfway there - But it only will send prerecorded or premade transport streams. The VCR might be unhappy if the TS doesn't have a real MPEG stream in there, but one could embed a low-bitrate 480i stream and fill the rest of the transport stream with data. (MPEG-2 Transport Streams as used in HDTV broadcasts allow for arbitrary data. For example, a Fox station broadcasting 480p with no subchannels is padding their 19.2 MBit/sec stream quite a bit.)
b) Current DVHS decks are rare and the ones that do exist don't have the best reliability record.
Re:It's an interesting poing, though (Score:2)
According to JVC, digital VHS can hold up to 4 hours of HDTV resolution or 24 hours of SDTV.
RSBEP page (Score:2)
Rsbep [netic.de] (Reed-Solomon and Burst Error Protection).
Looks like the current version is 0.0.4 with the caveat "it still gives occasional bit-errors, especially in Long-Play mode or with damaged tapes." The code is doubly FEC'ing data, which seems odd, but supposedly/should increases the integrity of the data.
Just some info...
Misplaced Application (Score:2, Interesting)
Is this really needed? (Score:2)
(...)this should let you backup 13GB in a cheap MiniDV tape in a safe manner, and restore it all later.
Hmm...
Re:Is this really needed? (Score:3, Informative)
Yes. There were a lot of backup devices around a few years back which let you back-up data to VHS for under $50, but the one thing they all had in common was that most of the time you couldn't restore it later, since VHS tapes are not very reliable.
Finally... (Score:2, Funny)
Finally a way to store all my mpeg's...
In a pinch, sure... (Score:3, Interesting)
As pointed out in the previous comments, DV cameras are not designed for lossless data handling, they are designed for video. Video is lossy, and while the tape and recorders are capable of error free capture and transfer, the emphasis is on making it good enough.
The cameras will dump the tapes at normal recorded video speed. If an error occurs in transfer (record or dump), the camera will keep going. If either computer in the chain is slow, you have to increase the error correction -- decreasing the available storage -- to handle those errors.
So, you end up getting better quality tapes and/or loosing capacity and speed.
Additionally, to use the DV you have to have a firewire port on the computer or drag along a card. If you have the time to do the prep work to put in a firewire card, you might want to consider getting a firewire hard drive -- and move from 5-10 gigs a tape to 60-120 gigs a drive. The speed is much higher too.
With that much forsight, you may as well pick a case that has USB 2.0 on it to cover systems that don't have firewire already. That's what I did, and it's worked out well. As can be expected, USB 1.x works too, though very slowly.
Might be a bad translation, but... (Score:4, Insightful)
But let's be even more realistic -- hard drives are almost $1/gig these days. Even if he has worked out the issues that are mentioned (lossy media...I really don't get the new discussion how lossy is lossless), the media deteriorates with age, seek time, etc, the cost savings just aren't there. The only advantage that I can see on this [assuming it does work well], is the physical size of the tapes, and so, you'll be able to pack more data into a fire safe.
Oh...and don't forget... at 13G/tape, you might be looking at 10+ tapes to back up some drives these days....It might be a cool hack, but changing tapes sucks...I'd still rather just mirror to another drive that I can remove, as the random access dramatically improves recovery time.
Re:Might be a bad translation, but... (Score:2)
If I have a mini-dv camera already, I can back up my drive for $10. I just saved $140 bucks and can store the backup somewhere outside my computer, safe for such things as fire, flood, or theft.
Hacking at its best, taking what you have and making it more useful.
Michael
How large are your drives? (Score:2)
Re:Might be a bad translation, but... (Score:2)
But if you're a home user, not backing up an IT department or your business machines, then you don't need to back the entire drive. Just the changes. And for a single PC, even with broadband, a day's worth of work isn't going to fill an entire 100GB hard disk, unless you're doing video production or audio editing with ProTools. Then your back in the "business" category of backups, and should buy a solution indexed to the cost to recreate lost data. Never backup $1000 worth of data on a $35 device unless you know your going to be able to recover it.
This isn't really a reply to your post per se, but slashdot in general. Everytime one of these "backup" related stories hits slashdot, it's always the same litany. "How do I backup my 136 GB hard disk? To another hard disk?" No. The answer is "You don't." Or "If you have to back up the WHOLE disk, you're doing it wrong."
1) Secure your computer.
If you tighten the permissions on your PC so that non-root/administrator can't write files wherever they please, this simplies backups greatly. You shouldn't be logged in as a privelidged user anyway except for maintenance. Your backup software can help you here, making a catalog of changed files to backup. If you see changes in
2) Don't back up worthless files.
Browser cache, history, temp files, print spool files, etc etc. Just exclude them from the backup script. You're probably saving yourself from future prosecution by not backing up any way, and some of the files get corrupted and are good to purge. If you don't backup worthless junk, there's less to backup.
3) Backup in sets to multiple media.
If you've done the above, then you can use algebra to make backups. If you've already backed up the OS and apps, and your permissions and backup scripts confirm for you that there are no interesting changes in those directories to backup... then you don't need to back them up! As long as you have a duplicate of each backup tape/cd/floppy (copy 1 of 2, copy 2 of 2) and you store them in different places, you're good. I've been running on incremental backups for months.
On a home machine, with good security and a good list of junk files to exclude, a days changes are at most 1 meg, but only if I download a large file. And that includes my wife's stuff too. With an aggressive backup scheme, it really doesn't matter how big the disk is but how much change in data from day to day you have to back up. And it gives you a good opportunity to learn about your system by keeping tabs on this.
With that kind of strategy, MiniDV looks actually pretty good. Just use 2 mDVs with the same backups on each, maybe "Winter 2003 copy 1 of 2" and "copy 2 of 2". That will hold 13GB of _changes_ to your system, which is quite alot, and might actually hold a year's worth for some people. With the reduced cost, it might be worth a look.
Backups in general (Score:2)
Yes, you can back up only incremental changes, however, if you're backing up to something like tape, you need to use a good backup program to maintain indexes of the tapes...
otherwise, you're going to be going through every last tape you have to find that file that someone accidentally deleted.
[for me, recovery time is key, as if I want something back, I want it now....but of course, all people are different, so some others may see the added cost/effort now to not be worth it]
Longevity of media (Score:2, Insightful)
the corner, then most tapes would have a very short lifespan.
Most companies that I have worked for that used tapes send them off site,
and put them into a controlled environment (humidity, temp, etc).
I used to think this was a good idea... (Score:3, Interesting)
Then again, for system backups which allow a complete restore of the whole lot, this could be handy, I guess. Especially since the "tape drives" (cameras) have lots of other uses. And I guess the speed of most DV cameras' rewind and fast-forward means that this would allow almost-speedy random-access.
It seems like this idea of backing up data to DV tape has been around for a while - but there's still no "prosumer"-ready application out there (yeah yeah, go write one yourself - but I'm not a programmer).
AIT - derived from 8mm video (Score:2)
On the other hand, I've been testing a HP Ultrium-2 drive, which costs a bomb-and-a-half, but is giving real speeds of 16MB/sec backing up, and close to the claimed 30MB/sec on restore. It won't stream unless your subsystem can handle 15MB/sec sustained, which is not trivial in the PC world. When it does, though, you can almost hear the slurping...
Great! So I can use my $1000 DV Camera for backup (Score:2)
This is a cool hack, but not very practical for most people.
This is not new (Score:2)
The way this one is set, you can put either 10 GB of data without error correction, or 5GB with error correction. It is rudimentary but in principle works and it is simple to implement. I guess it took me less than an hour to figure out how to make it work with my JVC miniDV cam.
MiniDV? (Score:2)
Re:MiniDV? (Score:2)
Re:google translation (Score:2, Informative)
here [google.com]