actually this is only an issue in HH, since HH writes all the stored messages into the same row, so locking is a problem
2011/10/21 Jérémy SEVELLEC <jsevel...@gmail.com>: > @Araron you're right and i was wrong! > > 2011/10/20 Yang <teddyyyy...@gmail.com> >> >> 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 >> > >> > > > > > -- > Jérémy >
