减少大型网站数据库i / o bottoleneck的最佳方法是什么？

For large web sites (traffic wise) that has alot of incoming reads and updates that end up being database I/Os, what're the best ways to mitigate the performance impact? one solution that I can think of is - for write, to cache and then do delayed write (using separate job); for read, use memcached concept. any other better solutions? For large web sites (traffic wise) that has alo