I just noticed I have this big file: C:\Users\(user name)\AppData\Roaming\Blender Foundation\Blender\2.66\cache\bvh_5A0601496B4787E1C017575FB7942F1F. This is on Windows 7.

Since I don't have blender installed, I guess it's from BURP.
I thought all BOINC project related files were confined to the BOINC folders, but I guess it's not true. I just don't remember seeing this behaviour described here on BURP anywhere...

---

Professor Desty Nova
Researching Karma the Hard way

The BVH is a bounding volume hierarchy cache and is used for the new experimental cycles renderer. This is definitely not supposed to go outside the BOINC folder (in fact I was under the impression that this particular set of data was stored in RAM and not on disk at all).

I'm afraid we will have to reject all new cycles renders until this issue has been fixed. For now I've added it to the known problems page and will return once I better understand what is going on with that cache file.

Thanks a lot for reporting this issue!

[Edit:] Turns out that it is a scene option added to cycles last year. Unfortunately, in addition to storing the file outside the project directory, if running multiple cycles renders and they start simultaneously, they may even remove each other's cache files and interfere with each other.

Good to know you discovered the problem fast.
It was just luck I noticed the file. I was analysing the disk to see if it needed defragmenting, and noticed this big fragmented file. I was curious, and then... Blender cache!!!???
This discovery also resolved another "mystery" I was having. I usually make daily backups, and the disk I use was getting filled pretty fast. Now I know why, with a new 1GiB file every time BURP runs. Now every time I see that BURP has run I go and delete the cache file.

---

Professor Desty Nova
Researching Karma the Hard way