found it , https://issues.apache.org/jira/browse/CASSANDRA-3387
On Thu, Oct 20, 2011 at 1:37 PM, aaron morton <aa...@thelastpickle.com> wrote: > It's unlikely that HH is the issue. (Disclaimer, am not familiar with HH in > 1.0, i know it's changes a bit) > Take a look at the TP Stats, what's happening ? > Cheers > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > On 20/10/2011, at 10:10 AM, Jérémy SEVELLEC wrote: > > Ok. > I think a degration could be normal because your cluster is in a degraded > state when a node is down. > With a replication_factor of 3 and with a 3 nodes cluster, each data you > write is replicated on each node. As One node is down, when writing, it's > impossible to send a replica on the down node and hints are send > : http://www.datastax.com/docs/1.0/dml/about_writes#hinted-handoff-writes > And it could be more expensive to achieve QUORUM when you read in that > context. > It may be one explanation. You can turn cassandra log into debug level to > see what happen when when there is a down node. > 2011/10/19 Yang <teddyyyy...@gmail.com> >> >> 3 >> >> sorry forgot this important info >> >> On Oct 19, 2011 11:31 AM, "Jérémy SEVELLEC" <jsevel...@gmail.com> wrote: >>> >>> Hi, what is your replication_factor? >>> >>> 2011/10/19 Yang <teddyyyy...@gmail.com> >>>> >>>> I'm using a cassandra version compiled from 1.0.0 github HEAD. >>>> >>>> I have 3 nodes, A B and C, on node A I run a client, which talks only >>>> to B as the coordinator. >>>> >>>> the performance is pretty good, a QUORUM read+write takes < 10ms. >>>> >>>> but then I shutdown C, quickly the performance starts to degrade, and >>>> QUORUM read+write time steadily increase to about 300ms. >>>> >>>> if I shutdown A and keep C, I observe the same effect. >>>> >>>> >>>> I understand that "2 out of 3" is going to give you faster response >>>> than "2 out of 2", but the difference should not be that dramatic as >>>> 10ms vs 300ms. >>>> >>>> any possible reasons for this?(or how to debug this?) >>>> >>>> Thanks >>>> Yang >>> >>> >>> >>> -- >>> Jérémy > > > > -- > Jérémy > >
