Over the last decade CPU speeds have increased dramatically while disk access times 
have only improved slowly.  This trend is likely to continue in the future and it will cause 
more and more applications to become disk-bound. [...] 
Log-structured file systems are based on the assumption that files are cached in main
memory and that increasing memory sizes will make the caches more and more effective 
at satisfying read requests.  As a result, disk traffic will become dominated by writes.