On 25 May 2010 09:04, David Boxenhorn <da...@lookin2.com> wrote: > I have seen several off-hand mentions that writes are inherently faster > than reads. Why is this so? >
In addition to the points that other posters made, writes only need to go as far as your battery-backed raid controller, whereas reads go all the way to the disc, possibly quite a lot of times (to search a tree structure for the right block). The client has no option but to wait for these. For durability, you just need the data to be in battery-backed ram in the controller, which is a pretty fast path, provided it has sufficient throughput to get the blocks on to disc faster than they're being written to (which should not be a problem for Cassandra's sequentially-written commit log and sstable files) Mark
