DataStax Support Forums » Tag: replication factor

DataStax Support Forums » Tag: replication factor - Recent Posts http://www.datastax.com/support-forums/tags/replication-factor Software, Support, and Training for Apache Cassandra en-US Thu, 20 Jun 2013 11:53:18 +0000 http://bbpress.org/?v=1.0.3 <![CDATA[Search]]> q http://www.datastax.com/support-forums/search.php rob4you on "Nodes were Unavailable" http://www.datastax.com/support-forums/topic/nodes-were-unavailable/page/2#post-7242 Wed, 31 Oct 2012 00:09:58 +0000 rob4you 7242@http://www.datastax.com/support-forums/ The problem doesn't seem to have been fixed. Look at this snippet: > CREATE KEYSPACE a WITH strategy_class = 'org.apache.cassandra.locator.SimpleStrategy' AND strategy_options:replication_factor='1'; > DESCRIBE KEYSPACE a; CREATE KEYSPACE a WITH strategy_class = 'SimpleStrategy' AND strategy_options:replication_factor='1'; > USE a; > CREATE TABLE t (id int PRIMARY KEY, col1 text); > SELECT * FROM t: Unable to complete request: one or more nodes were unavailable. > SHOW VERSION; [cqlsh 2.2.0 | Cassandra 1.1.5 | CQL spec 3.0.0 | Thrift protocol 19.32.0] I'm using DSE, latest release. thobbs on "Nodes were Unavailable" http://www.datastax.com/support-forums/topic/nodes-were-unavailable/page/2#post-5799 Fri, 10 Aug 2012 19:11:28 +0000 thobbs 5799@http://www.datastax.com/support-forums/ Thanks for the post! I sent a note to the docs team, so that should be fixed shortly. tstarbow on "Nodes were Unavailable" http://www.datastax.com/support-forums/topic/nodes-were-unavailable/page/2#post-5688 Thu, 09 Aug 2012 17:48:53 +0000 tstarbow 5688@http://www.datastax.com/support-forums/ It is pretty annoying that the "Getting Started Using the Cassandra CLI" for Cassandra 1.0 (<a href="http://www.datastax.com/docs/1.0/dml/using_cql" rel="nofollow">http://www.datastax.com/docs/1.0/dml/using_cql</a>) code doesn't work as written. It looks like it has been fixed on 1.1 docs: CREATE KEYSPACE twissandra WITH strategy_class = 'org.apache.cassandra.locator.SimpleStrategy' AND strategy_options:replication_factor='1'; Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-858 Thu, 15 Dec 2011 14:37:13 +0000 Anonymous 858@http://www.datastax.com/support-forums/ We were able to try the patch yesterday and we were able to run the hadoop job and read at CL of QUORUM. Thanks for the help. zznate on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-827 Thu, 08 Dec 2011 03:22:35 +0000 zznate 827@http://www.datastax.com/support-forums/ Ok, looks like you are getting hit by <a href="https://issues.apache.org/jira/browse/CASSANDRA-3551" rel="nofollow">https://issues.apache.org/jira/browse/CASSANDRA-3551</a> If you would like to apply the patch on the source and give it a try, this would actually be super valueable as an external test of the fix. zznate on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-824 Wed, 07 Dec 2011 16:46:10 +0000 zznate 824@http://www.datastax.com/support-forums/ We are currently looking into this and we'll update here as soon as we find something. Thanks for the extra details and patience. Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-823 Wed, 07 Dec 2011 14:53:16 +0000 Anonymous 823@http://www.datastax.com/support-forums/ 1.0.5 zznate on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-819 Wed, 07 Dec 2011 02:13:48 +0000 zznate 819@http://www.datastax.com/support-forums/ What version of Cassandra is this? This behavior certainly does not sound correct. Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-818 Tue, 06 Dec 2011 19:54:02 +0000 Anonymous 818@http://www.datastax.com/support-forums/ When we run the job and read with consistency level "QUORUM" the cluster's read latency will jump to over a minute, and we see the disk utilization hits 100%. When we run the same job against a keyspace with a replication factor of 1, CL "ONE", the read latency gets as high as 2 or 3 seconds and the disk utilization doesn't get above 55%. Are there settings we can change to help bring down the disk utilization on replicate keyspaces? Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-814 Mon, 05 Dec 2011 21:11:11 +0000 Anonymous 814@http://www.datastax.com/support-forums/ The replication factor is set to 3 and we have dropped the batch size ranges as low as 32. What metrics would you like and is there a way to print a report of the metrics? zznate on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-813 Mon, 05 Dec 2011 19:30:25 +0000 zznate 813@http://www.datastax.com/support-forums/ What is the replication factor and range batch size? Also, do you have any other metrics for performance of individual nodes? Like what is the OpsCenter output for the nodes when the timeouts occur? Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-810 Mon, 05 Dec 2011 17:18:34 +0000 Anonymous 810@http://www.datastax.com/support-forums/ When we run our hadoop job at read consistency "QUORUM" we get a timeout in the ColumnFamilyInputFormat. Our rows really aren’t that big (a few dozen columns @ a few KB per). We have a 4 node cluster running Cassandra 1.0.5. We have tried setting the timeout to a minute, as well as decreasing the range batch size, but we still end up with the following error: java.lang.RuntimeException: TimedOutException() at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.maybeInit(ColumnFamilyRecordReader.java:281) at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.computeNext(ColumnFamilyRecordReader.java:295) at org.apache.cassandra.hadoop.ColumnFamilyRecordReader$RowIterator.computeNext(ColumnFamilyRecordReader.java:183) at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:140) at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:135) at org.apache.cassandra.hadoop.ColumnFamilyRecordReader.nextKeyValue(ColumnFamilyRecordReader.java:139) at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:456) at org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67) at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:143) at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:647) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:32 Is there something we can check or try and/or change to keep from timing out? zznate on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-803 Mon, 05 Dec 2011 01:46:59 +0000 zznate 803@http://www.datastax.com/support-forums/ This is best summed up by the following: "Note that if W + R > ReplicationFactor, where W is the number of nodes to block for on write, and R the number to block for on reads, you will have strongly consistent behavior" ALL should only be used in situations where high availability is not required. Anonymous on "ColumnFamilyInputFormat - read and write consistency levels" http://www.datastax.com/support-forums/topic/columnfamilyinputformat-read-and-write-consistency-levels#post-800 Sat, 03 Dec 2011 19:38:25 +0000 Anonymous 800@http://www.datastax.com/support-forums/ When running a Hadoop job that uses a Cassandra column family as input, how does setting the read consistency affect the range scan used to get the input? Ie if we want to guarantee that a hadoop job runs on the most up to date information in a column family, is it better to have written with a consistency level of "ALL" so the job can read with consistency of "ONE" or to both read and write at a consistency level of "QUORUM"? Anonymous on "Nodes were Unavailable" http://www.datastax.com/support-forums/topic/nodes-were-unavailable/page/2#post-765 Thu, 24 Nov 2011 07:25:41 +0000 Anonymous 765@http://www.datastax.com/support-forums/ This is the link I followed : <a href="http://www.datastax.com/docs/1.0/dml/using_cql" rel="nofollow">http://www.datastax.com/docs/1.0/dml/using_cql</a>. Here there is nothing like replcaition factot in the command. Thanks, Raju.