Graphite

How Graphite FS handles inconsistancies

Asked by nickethier

Hello,

Imagine this setup:

When clustering graphite you have, for example, server1 with carbon cache and aggregation and server2 with the same setup. There is also a carbon-relay that sends all metrics to both carbon instances.

My question is what happens when a metric doesn't make it to one carbon instance but does to another. The whisper databases are not in sync then, server1 says metric x = a and server2 says metric x = b.

What does graphite do when you want to graph this data point?

Is there a way to ensure that your replicas are consistent?

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nickethier
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Eric Ziegenhorn (ziggy) said : 		#1

The first carbon instance to respond to the webapp frontend gets its data displayed. It's a race condition that results in erratic random results. You want to avoid this situation.

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nickethier (nickethier) said : 		#2

Thanks, its good to know this. I suspect the likely hood of it happening is close to none, just wanted to know the what ifs.