> Potential sources of simultaneous disk write : > > - Memtable flushing > - SSTable compaction/anticompaction > - SSTable streaming > - Commitlog writes (which should be on a different drive from data per > best practices anyway..)
Honestly though, last time I measured the effects of multiple streaming writers on modern fs:es (xfs and reiserfs at the time, several years ago) no appreciable difference was found in practice in terms of the resulting throughput you would get from reading the files back. But then, if you're unlucky you might trigger some degenerate case in allocation strategies, so who knows... But yes, it's certainly a very valid point that concurrent streaming I/O can be an issue. But as you say, given that there is a reasonably small amounts of concurrent writes that (except for the commit log) write in large chunks, it should not be a major concern. -- / Peter Schuller
