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Posted to user@cassandra.apache.org by Batranut Bogdan <ba...@yahoo.com> on 2015/01/13 11:01:43 UTC
2 Cassandra nodes slow
Hello,
I have a cluster of 6 C* nodes. All machines have the same hardware. I have noticed in opscenter that when I start reading a lot from the cluster 2 nodes have read latencies, but the rest do not have such high values. The replication factor for the keyspace is 3. Also those 2 nodes have latencies when measuring the CF Local Read Latency so I know that the reads on the main col family are slow on these 2 nodes. Partitioning is good since in the column family there are a few million possible values.Another thing is that I have stopped these 2 nodes and ran a few selections for 6000 rows .... those were executed in about 15 seconds. I have changed the keys so that I avoid caching as much as possible.Also I have done the same test when running with all nodes and the execution of the selection was abou 22 seconds....
Any ideeas?
I am thinking on rebuilding the data on the nodes... Stop the node , delete the data folder and restart... but I don't know the consequences....
Re: 2 Cassandra nodes slow
Posted by Batranut Bogdan <ba...@yahoo.com>.
Hello,
The data distribution is ok, as I sayd there area few milion distinct values for the keys. I am running repairs like this :Node 1st runs repair on 1 and 15th of the monthNode 3rd runs repair on 3 and 15th of the month and so on...
On Tuesday, January 13, 2015 1:47 PM, Rahul Neelakantan <ra...@rahul.be> wrote:
Is the data distribution OK? Have you tried running repairs?
Rahul
On Jan 13, 2015, at 5:01 AM, Batranut Bogdan <ba...@yahoo.com> wrote:
Hello,
I have a cluster of 6 C* nodes. All machines have the same hardware. I have noticed in opscenter that when I start reading a lot from the cluster 2 nodes have read latencies, but the rest do not have such high values. The replication factor for the keyspace is 3. Also those 2 nodes have latencies when measuring the CF Local Read Latency so I know that the reads on the main col family are slow on these 2 nodes. Partitioning is good since in the column family there are a few million possible values.Another thing is that I have stopped these 2 nodes and ran a few selections for 6000 rows .... those were executed in about 15 seconds. I have changed the keys so that I avoid caching as much as possible.Also I have done the same test when running with all nodes and the execution of the selection was abou 22 seconds....
Any ideeas?
I am thinking on rebuilding the data on the nodes... Stop the node , delete the data folder and restart... but I don't know the consequences....
Re: 2 Cassandra nodes slow
Posted by Rahul Neelakantan <ra...@rahul.be>.
Is the data distribution OK? Have you tried running repairs?
Rahul
> On Jan 13, 2015, at 5:01 AM, Batranut Bogdan <ba...@yahoo.com> wrote:
>
> Hello,
>
> I have a cluster of 6 C* nodes. All machines have the same hardware. I have noticed in opscenter that when I start reading a lot from the cluster 2 nodes have read latencies, but the rest do not have such high values. The replication factor for the keyspace is 3. Also those 2 nodes have latencies when measuring the CF Local Read Latency so I know that the reads on the main col family are slow on these 2 nodes. Partitioning is good since in the column family there are a few million possible values.
> Another thing is that I have stopped these 2 nodes and ran a few selections for 6000 rows .... those were executed in about 15 seconds. I have changed the keys so that I avoid caching as much as possible.
> Also I have done the same test when running with all nodes and the execution of the selection was abou 22 seconds....
>
> Any ideeas?
>
> I am thinking on rebuilding the data on the nodes... Stop the node , delete the data folder and restart... but I don't know the consequences....