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From "Logendran, Dharsan (Dharsan)" <dharsan.logend...@alcatel-lucent.com>
Subject RE: Question about out of sync
Date Wed, 15 Jan 2014 20:51:34 GMT
Thanks Rob,

It was quick.

Dharsan


From: Robert Coli [mailto:rcoli@eventbrite.com]
Sent: January-15-14 2:44 PM
To: user@cassandra.apache.org
Subject: Re: Question about out of sync

On Wed, Jan 15, 2014 at 11:36 AM, Logendran, Dharsan (Dharsan) <dharsan.logendran@alcatel-lucent.com<mailto: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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