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From Robert Coli <rc...@eventbrite.com>
Subject Re: I don't understand shuffle progress
Date Tue, 17 Sep 2013 19:43:01 GMT
On Tue, Sep 17, 2013 at 12:13 PM, Juan Manuel Formoso <jformoso@gmail.com>wrote:

> I am running shuffle on a cluster after upgrading to 1.2.X, and I don't
> understand how to check progress.
>

If your shuffle succeeds, you will be the first reported case of shuffle
succeeding on a non-test cluster. Until I hear a report of someone having
real world success, I recommend against using shuffle.

If you want to enable vnodes on a cluster with existing data, IMO you
should fork writes and bulk load a replacement cluster.


> I'm counting the lines of cassandra-shuffle ls, and it decreases VERY
> slowly. Sometimes not at all after 24 hours of processing.
>

I have heard reports of shuffle taking an insanely long amount of time,
such as this, as well.


> Is that value accurate?
>

Probably.


> Does the shuffle operation supports disabling/re-enabling (or restarting
> the cluster) and resuming from the last position? Or does it start over?
>

Yes, via the arguments "enable" and "disable". "clear" is what you use if
you want to clear the queue and start over.

Note that once you have started shuffle, you don't want to add/remove a
node until the shuffle is complete.

https://issues.apache.org/jira/browse/CASSANDRA-5525

=Rob

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