Hello Evelyn,

if we do what you say cassandra creates a new, empty column family directory on restart and the stops with the same exception.


One point i forgot to mention is that we've still got data in the commit log. (99.9% for other keyspaces). Are there any tools which we can use to examine the sstable or the commitlog files to dig further into this issue?

Or:
Can we setup a new cassandra installation and copy the data of the other keyspacs to the new instance?

The column family which shows this error does not contain important data. We're just very uncertain now what to do if this happens with important data. (ok - maybe this problem is not that important if we use a cluster of e.g. 3 nodes and a replication factor of 2 - but it leaves a strange impression about cassandra anyway).

greetings,
Michael


On 05.06.2018 15:31, Evelyn Smith wrote:
Hey Michael,

I have a hunch.

If the system doesn’t recognise the column family which is stopping
the node from starting perhaps try copying the column family directory
to a backup then deleting it.

Then restart Cassandra. If it starts I’ll assume the schema didn’t
have the column family:
* Create the column family again (be careful to create it exactly how
it was in the original schema);
* Stop Cassandra again;
* Move the SSTables from the column family backup into the new column
family folder (you have to do this as the column family folder will
have a UUID in it’s name that will have changed); and
* Restart Cassandra.
You should now have Cassandra running without losing your data.

If Cassandra doesn’t restart after deleting the column family
directory then just restore it from the backup and you are back to
square one.

Regards,
Evelyn.

On 5 Jun 2018, at 7:32 pm, m...@vis.at wrote:

Hi all!

We're using cassandra since a couple of month to get familiar with it. We're currently using only 1-node. Yesterday our server had to be restarted and now cassandra does not start anymore.

It reports:
INFO [main] 2018-06-05 09:50:43,030 ColumnFamilyStore.java:406 - Initializing system_schema.indexes INFO [main] 2018-06-05 09:50:43,036 ViewManager.java:137 - Not submitting build tasks for views in keyspace system_schema as storage service is not initialized INFO [main] 2018-06-05 09:50:43,283 ColumnFamilyStore.java:406 - Initializing system_traces.events INFO [main] 2018-06-05 09:50:43,286 ColumnFamilyStore.java:406 - Initializing system_traces.sessions INFO [main] 2018-06-05 09:50:43,287 ViewManager.java:137 - Not submitting build tasks for views in keyspace system_traces as storage service is not initialized INFO [main] 2018-06-05 09:50:43,300 ColumnFamilyStore.java:406 - Initializing m2m_auth.user INFO [main] 2018-06-05 09:50:43,302 ColumnFamilyStore.java:406 - Initializing m2m_auth.eventsbytag1 INFO [main] 2018-06-05 09:50:43,306 ColumnFamilyStore.java:406 - Initializing m2m_auth.mail2user ERROR [main] 2018-06-05 09:50:43,311 CassandraDaemon.java:706 - Exception encountered during startup java.lang.IllegalArgumentException: Unknown CF 0f6c8b36-5f34-11e8-a476-c93745f84272 at org.apache.cassandra.db.Keyspace.getColumnFamilyStore(Keyspace.java:204) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.db.view.ViewManager.addView(ViewManager.java:152) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.db.view.ViewManager.reload(ViewManager.java:125) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.db.Keyspace.<init>(Keyspace.java:324) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.db.Keyspace.open(Keyspace.java:127) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.db.Keyspace.open(Keyspace.java:104) ~[apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:292) [apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:600) [apache-cassandra-3.11.0.jar:3.11.0] at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:689) [apache-cassandra-3.11.0.jar:3.11.0]

We do not know how to bring it up again and e.g. stackoverflow only recommends to delete the node and let it rebuild (which we cannot do as we've only 1 node currently).
Can anybody drop us a hint ?

What can we do if our node does not start?

We've found an entry in the data directory with the given UUID but at the time when we restarted the node the whole keyspace was idle for a couple of hours. With the problem we're now _very_ concerned about data safety when we read that it can be a problem if e.g. tables are created/deleted/updated concurrently. But in our case we did not create/update tables concurrently and got this problem anyway....

Thanks for any help!

greetings,
Michael



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