I see the blu-ray format has multi-layers where it can burn 25 GB or 50 GB. My interest is for using them as data storage as a disc ROM, not for playing movies.
Can it address 50 GB as single storage, or does it have to be 25 GB per layer? If it is per layer, does the device mount as per layer so the system sees two 25 GB drives or as one 50 GB device?
The layers act as a single disc and you no more need to be aware of the breaks between layers than you need to know which side of which platter the data on your HD is stored on. However, personally I’d stick with 25 GB discs just because an extra layer gives an extra way for the disc to fail.
I agree with this. Even dual layer DVD-R discs can be iffy.
Come to think of it, I don’t think I’ve even come across someone supplying a DVD-R as dual, and that might very well be the reason.
OK, it sounds like sticking with 25 GB Blu-ray as single layer is a better idea. Any particular brand/model that works best?
Oh, they exist. But the last time I looked, they were disproportionatly expensive–as in, one double layered disc was 4 or 5 times the cost of two single layered disc (and by this I mean over a dollar verses 20 or 20 cents.) The one time I bought a spindle of dual layers, there were several coasters.
Verbatim have served me flawlessly for many years, DL included.
You probably don’t see DL-RW very often because two single layer discs are much cheaper.
I, too, concur that dual-layer DVD-Rs can be iffy and though I have no direct experience with dual-layer Blu-ray, the unreliability of dual-layer in DVD-Rs has left me with negative impressions. Specifically, on two different DVD burners that are supposed to be dual-layer capable, on two different computers, there was no problem writing the DVDs and IIRC no problem reading them, either, but there were major problems reading them on other devices. No problems at all with any brand of single layer. I still have a small stack of dual-layer DVD-R blanks that I never use.