ubifs:questions about this filesystem

[辉少]

Hi,MTD lists
I've got two questions about ubifs listed below,
1. If I write a file to the filesystem, dose it go to a new block or the same block last written file goes?
2. What's the priority of GC thread? If GC thread is working background, what effect will it bring to other working threads in my embedded system? Can other threads be blocked?

Best Regards,
Andy