My first suspicion would be to look at the server times in the cluster. It
looks like other cases where a write occurs (with no errors) but the data is
not retrieved as expected. If the write occurs with an earlier timestamp than
the existing data, this is the behavior you would see. The write would occur,
but it would not be the latest data to be retrieved. The write looks like it
fails silently, but it actually does exactly what it is designed to do.
Sean Durity
From: Mahesh Daksha <daks...@gmail.com>
Sent: Tuesday, April 09, 2019 9:10 AM
To: user@cassandra.apache.org
Subject: [EXTERNAL] Issue while updating a record in 3 node cassandra cluster
deployed using kubernetes
Hello All,
I have a 3 node cassandra cluster with Replication factor as 2 and read-write
consistency set to QUORUM. We are using Spring data cassandra. All
infrastructure is deployed using kubernetes.
Now in normal use case many records gets inserted to cassandra table. Then we
try to modify/update one of the record using save method of repo, like below:
ChunkMeta tmpRec = chunkMetaRepository.save(chunkMeta);
After execution of above statement we never see any exception or error. But
still this update state goes silent/fail intermittently. That is at times the
record in the db gets updated successfully where as other time it fails. Also
in the above query when we print tmpRec it contains the updated and correct
value every time. Still in the db these updated values doesn't get reflected.
We check the the cassandra transport TRACE logs on all nodes and found the our
queries are getting logged there and are being executed also with out any error
or exception.
Now another weird observation is this all thing works erfectly fine if I am
using single cassandra node (in kubernetes) or if we deploy above infra using
ansible (even works for 3 nodes for Ansible).
It looks some issue is specifically with the kubernetes 3 node deployment of
cassandra. Primarily looks like replication among nodes causing this.
Please suggest.
I have a 3 node cassandra cluster with Replication factor as 2 and read-write
consistency set to QUORUM. We are using Spring data cassandra. All
infrastructure is deployed using kubernetes.
Now in normal use case many records gets inserted to cassandra table. Then we
try to modify/update one of the record using save method of repo, like below:
ChunkMeta tmpRec = chunkMetaRepository.save(chunkMeta);
After execution of above statement we never see any exception or error. But
still this update fail intermittently. That is when we check the record in the
db sometime it gets updated successfully where as other time it fails. Also in
the above query when we print tmpRec it contains the updated and correct value.
Still in the db these updated values doesnt get reflected.
We check the the cassandra transport TRACE logs on all nodes and found the our
queries are getting logged there and are being executed also.
Now another weird observation is this all thing works if I am using single
cassandra node (in kubernetes) or if we deploy above infra using ansible (even
works for 3 nodes for Ansible).
It looks some issue is specifically with the kubernetes 3 node deployment of
cassandra. Primarily looks like replication among nodes causing this.
Please suggest.
Below are the contents of my cassandra Docker file:
FROM ubuntu:16.04
RUN apt-get update && apt-get install -y python sudo lsof vim dnsutils
net-tools && apt-get clean && \
addgroup testuser && useradd -g testuser testuser && usermod --password
testuser testuser;
RUN mkdir -p /opt/test && \
mkdir -p /opt/test/data;
ADD jre8.tar.gz /opt/test/
ADD apache-cassandra-3.11.0-bin.tar.gz /opt/test/
RUN chmod 755 -R /opt/test/jre && \
ln -s /opt/test/jre/bin/java /usr/bin/java && \
mv /opt/test/apache-cassandra* /opt/test/cassandra;
RUN mkdir -p /opt/test/cassandra/logs;
ENV JAVA_HOME /opt/test/jre
RUN export JAVA_HOME
COPY version.txt /opt/test/cassandra/version.txt
WORKDIR /opt/test/cassandra/bin/
RUN mkdir -p /opt/test/data/saved_caches && \
mkdir -p /opt/test/data/commitlog && \
mkdir -p /opt/test/data/hints && \
chown -R testuser:testuser /opt/test/data && \
chown -R testuser:testuser /opt/test;
USER testuser
CMD cp /etc/cassandra/cassandra.yml ../conf/conf.yml && perl -p -e
's/\$\{([^}]+)\}/defined $ENV{$1} ? $ENV{$1} : $&/eg; s/\$\{([^}]+)\}//eg'
../conf/conf.yml > ../conf/cassandra.yaml && rm ../conf/conf.yml && ./cassandra
-f
Please note conf.yml is basically cassandra.yml file having properties related
to cassandra.
Thanks,
Mahesh Daksha
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