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mayo32

File fragmentation support

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Hello.

Does ISO9660/UDF specification allows file fragmentation?

Let's say a need to write 40 GB big backup file to 50GB disc. Because I don't know how reliable this disc is I decided to create 8 GB of recovery files with par2 utility. I am assuming that most critical is the layer-break area (few MB before and after) therefore I write these par2 files to that critical area (to both layers) and because the 40 GB file will not fit to one layer it will be splitted to 2 areas, it will surround par2 files.

Thanks.

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That file size indicates you're burning to a bluray. Bluray doesn't have a layer break the way DVD has. Essentially a bluray is treated as 1 big 50gb sized layer.

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File size above 8.5GB indicates that BD-R is required. File size above ~23868MB indicates that BD-R DL is required. For my particular example I do not need to know where exactly the layer-break is (how much sectors are in each layer), it's somewhere in half of the disc. I need to write half of the file from beginning of the disc and second half of the file to the end of the disc. For the reason I mentioned before I want to avoid the layer-break area therefore I need to write a dummy file (or recovery files, which is more useful) to that area to fill almost entire disc capacity .

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No you don't need to, because there's no such thing as a layer break on BD's like there is on DVDs. BD's are meant to be treated as 1 giant layer. No more no less. Think of them a small hard drive.

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I'm just guessing, but I think the OP is thinking of layer change versus layer break.  It sounds like he wants a specific file to span between Layer 0 and Layer 1 on the BD-R/E DL.

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Seems this discussion changed it's topic to Layer-break.

Let's try with illustration. I need to create a DL disc  (it does not matter if it is DVD or BD) with following layout:

data_map.PNG

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