Bug Report: Large file size compare on ext devices fills hds drive & crashes computer

[Critcho]

Hi guys,

I'm trying to verify that 2000 photos have been successfully copied from my camera to my external hard drive. The camera USB3 connection mounts as mtp://Canon EOS 5D Mark IV/CF/DCIM/101EOS5D. The external USB-C hard drive mounts as I:\. There is about 50GB of photos to compare. When my computer started to lag, I launched TreeSize, and I noticed that the selected files to be compared are copied to %UserProfile%\AppData\Local\Temp\BC4F270.tmp\ as they are being compared. If I try to compare the entire 50GB, BC tries to copy all 50GB to the tmp folder, my SSD fills up, and my PC crashes. After the crash, the tmp is cleared.

If I tediously select 100 photos at a time (~2GB), tmp grows to ~2GB, but after the comparison is done, tmp is emptied, so the computer doesn't crash. But this means I have to keep comparing 20 batches of files, instead of letting it do its own thing in one operation.

I'll leave it to you to come up with the best solution for this... Don't use tmp? Delete each tmp file once the individual file comparison is done? See how much space is left on the SSD and do it in batches of half of that much then delete tmp?

Cheers,
Critcho

Sysinfo:
BC4.2.10.23938 on Win10.0.17134 64b

[Aaron]

Hello,

Because you have an MTP device, the temp files are necessary for the content comparison scan. However, BC4 should delete each tmp file as the content comparison finishes.

One hunch: if both of your devices is suitably fast (USB3 and USBC) it tries to grab as many temp files as it can, and deletes them as the scan completes. If the generating step is outpacing the scanning, that could be what is filling up the ssd.

Would it be possible to access the MTP files as a drive letter, such as an external card reader? This would workaround the temp file generation, accessing the device directly.

[Critcho]

Hi Aaron, thanks for the quick reply. I've tried mapping the drive, but Windows doesn't like it. I'll contact Canon support / forums and see if they can advise.

[Aaron]

Sure thing. If they aren't able to help bind as a drive letter directly, and the Canon supports a memory card format, it may be a solution to pull out the memory card and put it into a card reader that represents itself as a drive letter.