Today saw a post about swappiness in pythian. It recalls my memory of tuning oracle on linux.
Linux is great, but not all things on linux are optimal for database. There are two bad things. One is swappiness, another one is file cache. If you run oracle on linux default, you may find the file system cache often grabs huge memory and system is busy in paging out oracle processes. It's too bad.
The solution is 1) setting swappiness to zero, it tells linux to release file cache instead of swapping processes to disk when memory is tight 2) use DIRECT_IO (no file system caching in db2), it bypass file cache so not suffers double-buffering.
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