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From "Kurt Greaves (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-12296) system_auth can't be rebuilt by default
Date Wed, 12 Oct 2016 22:28:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-12296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15570067#comment-15570067
] 

Kurt Greaves commented on CASSANDRA-12296:
------------------------------------------

Don't insert your foot there too soon. Bootstrap is fine however you still get an incorrect
error message if you try and rebuild from the same DC using NTS from a DC that doesn't contain
the keyspace. When I was testing this case apparently the error got masked by another keyspace
which makes me think there may be another bug here (details for which are below) i.e:
{code}
 keyspace_name      | durable_writes | replication
--------------------+----------------+-------------------------------------------------------------------------------------
               test |           True |       {'class': 'org.apache.cassandra.locator.NetworkTopologyStrategy',
'dc1': '1'}

ccm node2 nodetool rebuild test dc2
 nodetool: Unable to find sufficient sources for streaming range (-1977532406384460074,-1976661853362798275]
in keyspace test with RF=1. Consider using NetworkTopologyStrategy for this keyspace.
{code}

In this case, node2 is in dc1, and although test isn't replicated to dc2 it still gets to
that error message.

I suppose alternatives could be:
1. Make the error more generic (e.g: 'Ensure this keyspace has replicas in the source datacentre')
2. Catch this case separately and warn that you can't rebuild from a DC that has no replicas.

Something more generic is probably OK and with a bit of thought the user should come to a
conclusion on how to deal with the issue like increase RF or change to NTS - As long as we
can be sure this only occurs from rebuilds. I can't see any path that leads to here from anywhere
other than a rebuild however I haven't completely ruled out bootstrap yet.

What do you think [~jjirsa]?

> system_auth can't be rebuilt by default
> ---------------------------------------
>
>                 Key: CASSANDRA-12296
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12296
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jim Witschey
>            Priority: Minor
>              Labels: lhf
>         Attachments: 12296.patch
>
>
> This came up in discussion of CASSANDRA-11687. {{nodetool rebuild}} was failing in a
dtest. [~pauloricardomg] explained:
> bq. before [CASSANDRA-11848] the local node could be considered a source, while now sources
are restricted only to dc2, so since {{system_auth}} uses {{SimpleStrategy}} depending on
the token arrangement there could or not be sources from dc2. Fix is to either use {{-Dcassandra.consistent.rangemovement=false}}
or update {{system_auth}} to use {{NetworkTopologyStrategy}} with 2 dcs..
> This is, at the very least, a UX bug. When {{rebuild}} fails, it fails with
> {code}
> nodetool: Unable to find sufficient sources for streaming range (-3287869951390391138,-1624006824486474209]
in keyspace system_auth with RF=1.If you want to ignore this, consider using system property
-Dcassandra.consistent.rangemovement=false.
> {code}
> which suggests that a user should give up consistency guarantees when it's not necessary.



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