Disk if full, but after clear cache and restart i see 12 GB free space. And then i start crawling and boom, no free space after 1-3 minutes.
With limited information, I cannot claim to know why you are seeing this problem. But if I were you, I would look at your disk settings. Here are some settings that are working for me.
/Performance_p.html
Is it possible that you are crawling sites with lots of .ISO/.zip/.rar files?
Have a look at “Loader Queue” in the crawling monitor to see if this is the case.