> Thanks for the reply. By packet drops I mean, the client is not able to read > the shared memory as fast as the software switch is writing into it.. > > What is the error you are getting on the client ?
> Also, I would like to know if in general , distribution of write requests > to different Casaandra nodes instead of only to one, leads to increased write > performance in Cassandra. > In general yes, clients should distribute their writes. > Is there any particular way in which write performance can be measured, > preferably from the client??? > > Logging at the client level ? Cheers ----------------- Aaron Morton New Zealand @aaronmorton Co-Founder & Principal Consultant Apache Cassandra Consulting http://www.thelastpickle.com On 18/12/2013, at 5:02 pm, Krishna Chaitanya <bnsk1990r...@gmail.com> wrote: > Thanks for the reply. By packet drops I mean, the client is not able to read > the shared memory as fast as the software switch is writing into it.. > I doubt its the issue with the client but can you in particular issues > that could cause this type of scenario? > Also, I would like to know if in general , distribution of write requests > to different Casaandra nodes instead of only to one, leads to increased write > performance in Cassandra. > Is there any particular way in which write performance can be measured, > preferably from the client??? > > On Dec 18, 2013 8:30 AM, "Aaron Morton" <aa...@thelastpickle.com> wrote: >> rite throughput is remaining at around 460 pkts/sec or sometimes even >> falling below that rate as against the expected rate of around 920 pkts/sec. >> Is it some kind of limitation of Cassandra or am I doing something wrong??? > There is nothing in cassandra that would make that happen. Double check your > client. > >> I also see an >> increase in packet drops when I try to store the packets from both the hosts >> into the same keyspace. The packets are getting collected properly followed >> by intervals in which they are being dropped in both the systems, at the >> same time. Could this be some kind of a buffer issue??? > What do you mean by packet drops ? > > Do you mean dropped messages in cassandra ? > >> Also, can write throughput be increased by distributing the write requests >> between the 2 Cassandra nodes instead of sending the requests to a single >> node? Currently, I dont see any improvement even if I distribute the write >> requests to different hosts. How can I improve the write performance overall? > Normally we expect 3k to 4k non counter writes per core per node, if you are > not seeing that it may be configuration or the client. > > Hope that helps. > > ----------------- > Aaron Morton > New Zealand > @aaronmorton > > Co-Founder & Principal Consultant > Apache Cassandra Consulting > http://www.thelastpickle.com > > On 15/12/2013, at 7:51 pm, Krishna Chaitanya <bnsk1990r...@gmail.com> wrote: > >> Hello, >> I am a newbie to the Cassandra world and have a few doubts which I >> wanted to clarify. I am having a software switch that stores netflow packets >> into a shared memory segment and a daemon that reads that memory segment and >> stores them into a 2-node Cassandra cluster. Currently, I am storing the >> packets from 2 hosts into 2 different keyspaces, hence only writes and no >> reads. The write throughput is coming to around 460 pkts/sec in each of the >> keyspaces. But, when I try to store the packets into the same keyspace, I >> observe that the write throughput is remaining at around 460 pkts/sec or >> sometimes even falling below that rate as against the expected rate of >> around 920 pkts/sec. Is it some kind of limitation of Cassandra or am I >> doing something wrong??? >> I also see an >> increase in packet drops when I try to store the packets from both the hosts >> into the same keyspace. The packets are getting collected properly followed >> by intervals in which they are being dropped in both the systems, at the >> same time. Could this be some kind of a buffer issue??? >> The write requests from both the systems are >> sent to the same node which is also the seed node. I am mostly using the >> default Cassandra configuration with replication_factor set to 1 and without >> durable_writes. The systems are i5s with 4 gb RAM. The data model is: each >> second is the row key with all the packets collected in that second as the >> columns. Also, can write throughput be increased by distributing the write >> requests between the 2 Cassandra nodes instead of sending the requests to a >> single node? Currently, I dont see any improvement even if I distribute the >> write requests to different hosts. How can I improve the write performance >> overall? >> >> Thanks. >> -- >> Regards, >> BNSK. >
