cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Branislav Janosik -T (bjanosik - AAP3 INC at Cisco)" <>
Subject Re: Cassandra cluster performance
Date Thu, 22 Dec 2016 17:22:50 GMT
Yes, there is definitely something wrong but I’m struggling to figure out what exactly. To
answer your questions.

-          There are no errors in client or Cassandra

-          I tried manual inserts and there are no errors either, I set the tracing on so
I can see that the data is distributed to different partitions. Even when I use nodetool status,
the Owns is 48.4% to 51.6%.

From: Ben Slater <>
Reply-To: "" <>
Date: Wednesday, December 21, 2016 at 6:20 PM
To: "" <>
Subject: Re: Cassandra cluster performance

Given you’re using replication factor 1 (so each piece of data is only going to get written
to one node) something definitely seems wrong. Some questions/ideas:
- are there any errors in the Cassandra logs or are you seeing any errors at the client?
- is your test data distributed across your partition key or is it possible all your test
data is going to a single partition?
- have you tried manually running a few inserts to see if you get any errors?


On Thu, 22 Dec 2016 at 11:48 Branislav Janosik -T (bjanosik - AAP3 INC at Cisco) <<>>

- Consistency level is set to ONE
-  Keyspace definition:

                    "CREATE KEYSPACE  IF NOT EXISTS  onem2m " +
        "WITH replication = " +
        "{ 'class' : 'SimpleStrategy', 'replication_factor' : 1}";

- yes, the client is on separate VM

- In our project we use Cassandra API version 3.0.2 but the database (cluster) is version

- for 2node cluster:

         first VM: 25 GB RAM, 16 CPUs

         second VM: 16 GB RAM, 16 CPUs

From: Ben Slater <<>>
Reply-To: "<>" <<>>
Date: Wednesday, December 21, 2016 at 2:32 PM
To: "<>" <<>>
Subject: Re: Cassandra cluster performance

You would expect some drop when moving to single multiple nodes but on the face of it that
feels extreme to me (although I’ve never personally tested the difference). Some questions
that might help provide an answer:
- what consistency level are you using for the test?
- what is your keyspace definition (replication factor most importantly)?
- where are you running your test client (is it a separate box to cassandra)?
- what C* version?
- what are specs (CPU, RAM) of the test servers?


On Thu, 22 Dec 2016 at 09:26 Branislav Janosik -T (bjanosik - AAP3 INC at Cisco) <<>>
Hi all,

I’m working on a project and we have Java benchmark test for testing the performance when
using Cassandra database. Create operation on a single node Cassandra cluster is about 15K
operations per second. Problem we have is when I set up cluster with 2 or more nodes (each
of them are on separate virtual machines and servers), the performance goes down to 1K ops/sec.
I follow the official instructions on how to set up a multinode cluster – the only things
I change in Cassandra.yaml file are: change seeds to IP address of one node, change listen
and rpc address to IP address of the node and finally change endpoint snitch to GossipingPropertyFileSnitch.
The replication factor is set to 1 when having 2-node cluster. I use only one datacenter.
The cluster seems to be doing fine (I can see nodes communicating) and so is the CPU, RAM
usage on the machines.

Does anybody have any ideas? Any help would be very appreciated.


View raw message