Yes, unfortunately you have to know whether your software is thinking in decimal figures or binary ones - and then translate the effective capacity accordingly. But the end result is the same either way: figure about 85-90 minutes of HQ footage on a single-layer Blu-ray disc.

Interesting point that hard drives are currently cheaper than Blu-ray discs per GB, but hard drives are unreliable as a permanent storage medium - and we don't know whether Blu-ray discs are reliable. Ideally you might make one backup on a hard drive and another on Blu-ray to have both redundant copies and alternative resistance to failure (depending on stress conditions).

Did they give a reason for this, Craig? And if so, how do you split up an over 25gb bpav folder (let's say from a 3-hour recording on a phu drive) for a data archive disk?

I have had to do this for a large project and yes it can be done. Refer to the XDCAM EX Clip Browser Manual for combining and splitting BPAV folders. There are in fact, settings in the Clip Browser to split for Blu-ray archival at 25GB (Disc 1) and 50GB (Disc 2), see page 30-31 of the manual (ver 1.2.5). Once they are split, it simply a matter of using your Blu-ray burning software to make a data disc (in my case, I use Toast 10 on the Mac). I've made both 25GB and 50GB data archival discs with BPAV folders. Cheers!

I can't recall the reason but it may have to do with laser focus over time.

I'm still using DL-DVD but considering the drop in prices of both media and burners and the possible faster burn speed, I'm considering moving to blu-ray.

ClipBrowser2 has a split function which ensures the data will fit (didn't work properly in ClipBrowser1).

Thanks, guys, I see it under "Splitting Folders". Looks pretty straightforward.

re-writable
 

Any issues with using a re-writable disc for archiving?

I'd like to continually add to the blu-ray disc as I accumulate more material rather than wait till I have 80 minutes of material before archiving.

I'm thinking of a system where I have a primary space on the computer HDD with an external HDD for initial backup plus the re-writable DVD for secondary back up. Then when the external HDD fills I can make a second non re-writable DVD for archiving. Longer term I'd have a re-writable and a non re-writable set of DVD's as backup of all pertinent files.

I'll also be doing some travel. I could leave the external HDD behind and make backups to re-writable DVD's. DVD's would seem to be a safer bet for the bumps and bruises of travelling.