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Posted to commits@cassandra.apache.org by "Jeremy Hanna (JIRA)" <ji...@apache.org> on 2019/01/08 18:33:00 UTC
[jira] [Commented] (CASSANDRA-14957) Rolling Restart Of Nodes Cause
Dataloss Due To Schema Collision
[ https://issues.apache.org/jira/browse/CASSANDRA-14957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16737379#comment-16737379 ]
Jeremy Hanna commented on CASSANDRA-14957:
------------------------------------------
The schema has to agree across the cluster. If a node is being restarted, it has to catch up with the schema before being able to process writes to the new table. Until then, it will probably have messages in the logs that it can't identify a table with a certain id.
How did you determine that there was data loss outside of temporary inconsistency between nodes? If the writes succeeded on other nodes at the consistency level you specified, then there wasn't data loss. You just had a temporary inconsistency on the node being restarted. So the normal anti entropy operations like read repair and full repair should get it back into a consistent state.
> Rolling Restart Of Nodes Cause Dataloss Due To Schema Collision
> ---------------------------------------------------------------
>
> Key: CASSANDRA-14957
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14957
> Project: Cassandra
> Issue Type: Bug
> Components: Cluster/Schema
> Reporter: Avraham Kalvo
> Priority: Major
>
> We were issuing a rolling restart on a mission-critical five node C* cluster.
> The first node which was restarted got the following messages in its system.log:
> ```
> January 2nd 2019, 12:06:37.310 - INFO 12:06:35 Initializing tasks_scheduler_external.tasks
> ```
> ```
> WARN 12:06:39 UnknownColumnFamilyException reading from socket; closing
> org.apache.cassandra.db.UnknownColumnFamilyException: Couldn't find table for cfId bd7200a0-1567-11e8-8974-855d74ee356f. If a table was just created, this is likely due to the schema not being fully propagated. Please wait for schema agreement on table creation.
> at org.apache.cassandra.config.CFMetaData$Serializer.deserialize(CFMetaData.java:1336) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.db.partitions.PartitionUpdate$PartitionUpdateSerializer.deserialize30(PartitionUpdate.java:660) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.db.partitions.PartitionUpdate$PartitionUpdateSerializer.deserialize(PartitionUpdate.java:635) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.db.Mutation$MutationSerializer.deserialize(Mutation.java:330) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.db.Mutation$MutationSerializer.deserialize(Mutation.java:349) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.db.Mutation$MutationSerializer.deserialize(Mutation.java:286) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.net.MessageIn.read(MessageIn.java:98) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.net.IncomingTcpConnection.receiveMessage(IncomingTcpConnection.java:201) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.net.IncomingTcpConnection.receiveMessages(IncomingTcpConnection.java:178) ~[apache-cassandra-3.0.10.jar:3.0.10]
> at org.apache.cassandra.net.IncomingTcpConnection.run(IncomingTcpConnection.java:92) ~[apache-cassandra-3.0.10.jar:3.0.10]
> ```
> The latter was then repeated several times across the cluster.
> It was then found out that the table in question `tasks_scheduler_external.tasks` was created with a new schema version after the entire cluster was restarted consecutively and schema agreement settled, which started taking requests leaving the previous version of the schema unavailable for any request, thus generating a data loss to our online system.
> Data loss was recovered by manually copying SSTables from the previous version directory of the schema to the new one followed by `nodetool refresh` to the relevant table.
> The above has repeated itself for several tables across various keyspaces.
> One other thing to mention is that a repair was in place for the first node to be restarted, which was obviously stopped as the daemon was shut down, but this doesn't seem to do with the above at first glance.
> Seems somewhat related to:
> https://issues.apache.org/jira/browse/CASSANDRA-13559
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