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https://issues.apache.org/jira/browse/STORM-885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15009640#comment-15009640
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ASF GitHub Bot commented on STORM-885:
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Github user d2r commented on a diff in the pull request:
https://github.com/apache/storm/pull/838#discussion_r45128439
--- Diff: docs/documentation/Pacemaker.md ---
@@ -0,0 +1,89 @@
+# Pacemaker
+
+### Introduction
+Pacemaker is a storm daemon designed to process heartbeats from workers.
As Storm is scaled up, ZooKeeper begins to become a bottleneck due to high
volumes of writes from workers doing heartbeats. Lots of writes to disk and
traffic across the network is generated as ZooKeeper tries to maintain
consistency.
--- End diff --
`Lots of writes to disk and lots of traffic`...
> Heartbeat Server (Pacemaker)
> ----------------------------
>
> Key: STORM-885
> URL: https://issues.apache.org/jira/browse/STORM-885
> Project: Apache Storm
> Issue Type: Improvement
> Components: storm-core
> Reporter: Robert Joseph Evans
> Assignee: Kyle Nusbaum
>
> Large highly connected topologies and large clusters write a lot of data into
> ZooKeeper. The heartbeats, that make up the majority of this data, do not
> need to be persisted to disk. Pacemaker is intended to be a secure
> replacement for storing the heartbeats without changing anything within the
> heartbeats. In the future as more metrics are added in, we may want to look
> into switching it over to look more like Heron, where a metrics server is
> running for each node/topology. And can be used to aggregate/per-aggregate
> them in a more scalable manor.
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