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From Robert Coli <rc...@eventbrite.com>
Subject Re: Question about out of sync
Date Wed, 15 Jan 2014 19:43:48 GMT
On Wed, Jan 15, 2014 at 11:36 AM, Logendran, Dharsan (Dharsan) <
dharsan.logendran@alcatel-lucent.com> wrote:

>  Lets say we have a two nodes cluster(node_a and node_b) with the
> replication factor of 2.  It means both nodes(node_a and node_b) will have
> the same amount of data replicated. If one node(node_b) goes down and comes
> back. Is there any way for us to find out how the node_b is behind(out of
> sync) or  needs  to catch up.  The amount could be in bytes, number of rows
> for each column family etc.
>

You can see how many hints node_a has stored for node_b, and look at how
large that is on disk, but that's about it. If you exhaust
max_hint_window_in_ms there is literally no way to know how out of sync you
are until you run repair.

Other notes :

1) If you're asking this question, you probably have not internalized what
the "eventual" part of eventual consistency really means to your
application.
2) RF=N=2 is not a recommended production configuration. Minimal
recommended is usually RF=3, N=6.

=Rob

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