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From Jean-Yves LEBLEU <>
Subject Re: Changing column families and drain
Date Wed, 13 Oct 2010 19:15:27 GMT
Thank you for your comments.

You are right we are running 0.6.4, and we are changing column family type
to supercolumn.
So the idea is to export data, stop all the nodes in the ring, remove data
files, restart all nodes with the new storage-conf and reimport data.

On Wed, Oct 13, 2010 at 2:07 PM, aaron morton <>wrote:

> I've always assumed that when the drain command logs that the node is
> drained the commit log is clear. The drain command stops the node from
> accepting requests, flushes the memtables to disk and finally marks the
> commit logs as safe to delete. As far as I can tell, it should either work
> or fail.
> If a second of the log cannot be discard the command will log at debug
> level "Not safe to delete commit log...". But AFAIK once the memtables are
> flushed and more more writes accepted you are good to go.
> If you are dropping CF's then you should be able to deploy the code to stop
> querying them and then do a rolling change in the cluster. If you are
> renaming then it may be a bit trickier.
> Shutting down with kill -9 is the approved way to stop cassandra.
> Also, am assuming you are on 0.6*.
> Hope that helps
> Aaron
> On 13 Oct 2010, at 21:00, Jean-Yves LEBLEU wrote:
> Hi all,
> When I look at the wiki the procedure to change the column family is :
>    1. Empty the commitlog with "nodetool drain."
>    2. Shutdown Cassandra and verify that there is no remaining data in the
>    commitlog.
>    3. Delete the sstable files (-Data.db, -Index.db, and -Filter.db) for
>    any CFs removed, and rename the files for any CFs that were renamed.
>    4. Make necessary changes to your storage-conf.xml.
>    5. Start Cassandra back up and your edits should take effect. **
> How do we check that the commitlog is empty ? as it seems that there are
> still files in the commit log directory after a drain ?
> Is it necessary to shutdown all nodes in a ring before changing the
> storage-conf.xml files ?
> On linux is a "kill -9" acceptable as a cassandra shutdown ?
> Thanks for answer.
> Jean-Yves
> **

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