On Fri, Jan 23, 2015 at 9:59 AM, Kevin Burton <bur...@spinn3r.com> wrote:
> The WAL (and walls in general) impose a performance overhead. > > If one were to just take a machine out of the cluster, permanently, when a > machine crashes, you could quickly get all the shards back up to N replicas > after a node crashes. > It depends a bit on your consistencylevel and frequency of repair, and (as Rusty says) how much you care about your data. But why take the machine out? Just have it rejoin... taking it out means you lower the "unique replica count" by one and lose any data that for whatever reason was only propagated there. But yes, the overhead of the commit log is why the durable_writes:false cassandra.yaml option exists. Some people are ok with losing everything that was in a memtable on only the single crashed node; most are not, and should not disable the commit log. =Rob
