CAS operation result is unknown - proposal accepted by 1 but not a quorum

[Ralph Boehme]

Hi folks!

Ralph here from the Samba team.





- fast
- fast
- fast
- highly consistent, iow linearizable









This happens when executing the following LWT:

        f'''
        INSERT INTO {dbname} (key, guid, owner, refcount)
        VALUES (?, ?, ?, ?)
        IF NOT EXISTS
        ''')



# nodetool status
Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving


Can anyone shed some light on what I might be doing wrong?

Thanks!
-slow

[1] <https://wiki.samba.org/index.php/CTDB_and_Clustered_Samba>

I'm currently doing research into Opensource distributed NoSQL key/value stores to be used by Samba as an more scalable alternative to Samba's own homegrown distributed key/value store called "ctdb" [1]. As an Opensource implementation of the SMB filesharing protocol from Microsoft, we have some specific requirements wrt to database behaviour: We got away without a linearizable database as historically the SMB protocol and the SMB client implementations were built around the assumption that handle and session state at the server could be lost due to events like process or server crashes and client would implement a best effort strategy to recover client state. Modern SMB3 offers stronger guarantees which require a strongly consistent ie linearizable database. While prototyping a Python module for our pluggable database client in Samba I ran into the following issue with Cassandra: File "cassandra/cluster.py", line 2618, in cassandra.cluster.Session.execute File "cassandra/cluster.py", line 4901, in cassandra.cluster.ResponseFuture.result cassandra.protocol.ErrorMessageSub: <Error from server: code=1700 [Unknown] message="CAS operation result is unknown - proposal accepted by 1 but not a quorum."> This is the first time I'm running Cassandra. I've just setup a three node test cluster and everything looks ok: -- Address Load Tokens Owns (effective) Host ID Rack UN 172.18.200.21 360,09 KiB 16 100,0% 4590f3a6-4ca5-466f-a24d-edc54afa36f0 rack1 UN 172.18.200.23 326,92 KiB 16 100,0% 9175fd4e-4d84-4899-878a-dd5266132ff8 rack1 UN 172.18.200.22 335,32 KiB 16 100,0% 35e05369-cc8a-4642-b98d-a5fcc326502f rack1

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