When you absolutely, positively, need a RELIABLE backup

[jmkeuning]

I have been backing up data to CDs, then, later, to DVDs, for years. I have, on occasion, gone to retrieve a back-up and got a CRC error. If you have ever encountered one of these, you know that Windows stops copying at the error and you are stuck. Fortunately, programs like IsoBuster and MagicISO will create an ISO, ignoring errors. The problem is, when you create the ISO, and then extract the contents of that ISO, the error will likely have corrupted a file, maybe more. This was not a problem for me when I was backing up things like audiobooks because all I really lose is an mp3, PART of an mp3 if I am able to "repair" the mp3. However, is this error occurred on a .DOC or .PDF you could have irreparable damage. What's the point of backing up if you can't retrieve the back up?

Now, with these video back-ups, where you have essentially one "file" on a DVD, you could lose the whole file to a CRC error. You are gonna be pissed in a few years when your backup is crap.

I started making PAR files for all my backups. Using Quickpar you can create a parity set that will fix corrupted files. The beauty of the PAR files is that if you do have a CRC error, you can create the ISO, extract the contents of the ISO, and then repair the damaged files with the PAR files.

So here is what I just did. I am just posting this for the newbies; the veterans know this or have other methods for ensuring sound, reliable backups. I just backed up a DVD movie. I used DVDShrink to burn a copy of the DVD. Realizing that this DVD might get a CRC error and be unrecoverable at a later date I wanted to make sure that I have a way of recovering the data. After using DVDShrink to burn my video DVD, I used DVD shrink again to make an ISO. However, rather than using the DVD5 setting I went into preference and set up a custom file size of 4 gigs. Then I took my 4 gig file and created a 10% par set for that ISO. After that, all this data fit on a DVD. Of course, if you wanted to, you could create a full-size ISO and then make whatever size PAR set that you want and just burn the PAR files to a separate DVD. This is a little less practical as now you have an organizational problem - PAR files on a different disc. Putting all the files on one disc gives you a self-contained recovery disc. If you were really crazy you could even put the QuickPar installer on the disc so you could recover it anytime, anywhere.

For what its worth, I have a DVD camcorder, my first video camera, and I have taken many many gigs of video of my first child. Obviously, I do not want to lose this video!

My two cents. Take it or leave it!

[guns1inger]

An interesting idea. The DVD Video design does have built-in safeguards in the form of the BUP file, however only imgburn 2 seems to actually burn DVD Video with the correct safety margin between the IFO and the BUP files to make it worthwhile.

What happens if your PAR files and your data are both corrupt ?

[Bjs]

My two cents then ... considering backups are more than just important .

If your serious about achival backups , that last ... consider dat backup unit .



Replace the tape every 2 years is good advice , though we have had tape's stored for more than 5 years (writen once / stored as long term backups / never accessed) , recently tested , and all perfect .

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If cd/dvd backup and par are buggered ... you are too ... dont rely on it .

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The code for image is not my doing ...

[jmkeuning]

What happens if your PAR files and your data are both corrupt ?

That's actually the cool thing abour PAR files. If you make a 10% PAR files, you can repair up to 10% of missing data from the file set - 10% of the files could be completely gone and you would still be good to go. If the PAR files are damaged, that just limits how much damage you can repair. So if a PAR file gets damaged maybe you can only repair 8 or 9 % of the fileset.

Regarding built-in safeguards in the DVD file structure - I am curious about this. As I said in another thread, I have a DVD (original) with a CRC error, I just could not get it backed up. Eventually, RipIt4Me did the job but it removed some data. I wonder what this data is... will their be a hitch in the video somehere? What happens if a VOB gets damaged? Can you repair the VOB and then re-author the DVD?