Strange thing is going on on my site.. In my cache/supercache folder from time to time i can find folders with not just my site name, but also with name of some known/unknown sites.. sometimes those are warez sites, sometimes sites of some very known airline company etc.. I delete them, and then, few days/weeks later, some others are there.. inside those folders is just index.html of my site, but folder names are definitely not from my site.. I was previous on shared hosting, never had that problem. Last months i'm on my own vps, and now i have those problems. Cache folder is 755, also supercache. Should i change any of that permissions?
I also have one other problem, i believe it is something related to wp-supercache, but not 100% sure. Once or twice a day my vps get stucked, and my tmp folder is full with files ending with MYI and MYD. Those files go up to 100MB, there can be up to 45 of them, i think i never saw more. Files are being deleted, and then once again being created. I opened some of those files, and they are full with links of posts on my site and comments. wp-supercache-gc is being mentioned a lot of times in those files.. I have strong vps, 4 cores, 2Gb ram, a lot of free space and 4 gb swap, but site becomes unreachable for half an hour or whole hour. I have 5.000 posts and 75.000 comments, also 15.000 visits daily average. And even in peak times, vps is not so stucked like in those moments. Yesterday i thought it may be because of wp-supercache preload mode which works with so many posts (i tried to set it to work with smaller number, but whenever i publish a new post number goes back to preload "all"), so i disabled preload mode, but id like to have it enabled of course. I'l see now can this be a problem, or garbage collector.. Can you recommend good settings for gc for my site? A lot of new comments (hundreds per day average), average 10 new posts daily.. GC is now using default settings.
Thanks for any help and suggestions in advance.