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From "Yang Yang (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-2019) add interface to DatabaseDescriptor to help setting seeds and tokens at boot time (for EC2 feature)
Date Mon, 24 Jan 2011 18:18:43 GMT


Yang Yang commented on CASSANDRA-2019:

Thanks, I see that SSMBean does have a move() call now. so with CASSANDRA-526  committed,
we should be able to achieve resetting the token before the node starts participating in the

then we can consider this jira solved.


> add interface to DatabaseDescriptor to help setting seeds and tokens at boot time (for
EC2 feature)
> ---------------------------------------------------------------------------------------------------
>                 Key: CASSANDRA-2019
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>    Affects Versions: 0.7.0
>            Reporter: Yang Yang
>             Fix For: 0.7.1
>         Attachments: DBdscrpt.diff
> 1)
> in the amazon EC2 environment, machines die off and more frequently, and new instances
are brought up more often, so even if we list out all the nodes in the ring as seeds, all
of these seeds may have gradually died off after some time. at that time , new nodes joining
won't be able to find the existing ring, and will establish a new, separate ring of the same
name, which is wrong. 
> we have made some custom code that utilizes external systems to figure out the EC2 autoscaler
group, and at boot time feed this info to the new node. but this requires the new node to
be able to modify the seeds at boot time. right now the DatabaseDescriptor only has a getSeeds()
method, we would like to add a setSeeds()
> 2) similarly, for the token-1  trick, we wrote code to do this automatically.  the StorageService.initServer()
code reads the initialToken at boot time, we need to be able to modify this  at boot time.
so we would like to add DatabaseDescriptor.setInitialToken()
> patch attached. 
> also theoretically we could do both just by modifying the config file, but that requires
running a separate process before cassandra daemon starts, which is not as clean.
> Thanks a lot 
> Yang

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