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new ebdfcf2 Added September 2021 blog post: "Reaper: Anti-entropy Repairs
Made Easy" about running repairs using Reaper
ebdfcf2 is described below
commit ebdfcf2027eefeba75efda3cb61a481b49041e0f
Author: Diogenese Topper <diotop...@gmail.com>
AuthorDate: Tue Sep 14 15:08:54 2021 -0700
Added September 2021 blog post: "Reaper: Anti-entropy Repairs Made Easy"
about running repairs using Reaper
patch by Alexander Dejanovski, Diogenese Topper; reviewed by Erick
Ramirez, Mick Semb Wever for CASSANDRA-16964
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b/site-content/source/modules/ROOT/pages/blog.adoc
index e73eb44..e190232 100644
--- a/site-content/source/modules/ROOT/pages/blog.adoc
+++ b/site-content/source/modules/ROOT/pages/blog.adoc
@@ -39,9 +39,33 @@
xref:blog/Apache-Cassandra-Changelog-10-October-2021.adoc[Read More]
[openblock,card-header]
------
[discrete]
+=== Reaper: Anti-entropy Repair Made Easy
+[discrete]
+==== September 28, 2021
+------
+[openblock,card-content]
+------
+Originally designed by Spotify, Reaper is an open source written in Java to
schedule and orchestrate repairs of Apache Cassandra clusters. It helps make
repairs as safe and reliable as possible, and with the recent release of Apache
Cassandra 4.0 that also includes incremental repairs.
+
+[openblock,card-btn card-btn--blog]
+--------
+[.btn.btn--alt]
+xref:blog/Reaper-Anti-entropy-Repair-Made-Easy.adoc[Read More]
+--------
+
+------
+----
+//end card
+
+//start card
+[openblock,card shadow relative test]
+----
+[openblock,card-header]
+------
+[discrete]
=== Join Cassandra at Apachecon 2021
[discrete]
-==== August 27, 2021
+==== September 20, 2021
------
[openblock,card-content]
------
@@ -66,7 +90,7 @@ xref:blog/Join-Cassandra-at-ApacheCon-2021.adoc[Read More]
[discrete]
=== Cassandra on Kubernetes: A Beginner's Guide
[discrete]
-==== August 27, 2021
+==== September 4, 2021
------
[openblock,card-content]
------
diff --git
a/site-content/source/modules/ROOT/pages/blog/Reaper-Anti-entropy-Repair-Made-Easy.adoc
b/site-content/source/modules/ROOT/pages/blog/Reaper-Anti-entropy-Repair-Made-Easy.adoc
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+++
b/site-content/source/modules/ROOT/pages/blog/Reaper-Anti-entropy-Repair-Made-Easy.adoc
@@ -0,0 +1,82 @@
+= Reaper: Anti-entropy Repair Made Easy
+:page-layout: single-post
+:page-role: blog-post
+:page-post-date: September 28, 2021
+:page-post-author: Alexander Dejanovski
+:description: The Apache Cassandra Community
+:keywords:
+
+Reaper is an open source tool written in Java and built with Dropwizard to
schedule and orchestrate repairs of Apache Cassandra clusters. It was
originally
https://www.slideshare.net/planetcassandra/spotify-automating-cassandra-repairs[designed
and open-sourced by Spotify,window=_blank] in an attempt to automate repairs
while applying best practices from their solid production experience.
+
+=== Repair Challenges
+
+Anti-entropy repair is traditionally performed using the nodetool repair
command. It can be performed in two ways, full or incremental, and configured
to repair various token ranges: all, primary range, or sub-range. Add to this
different validation compaction orchestration settings (sequential, parallel,
and data center aware), the fact that anti-compaction may trigger in some
cases, and you're down a rabbit hole of complexity. All this for an operation
that is mandatory and should be s [...]
+In the 1.x/2.x days of Cassandra (and probably after that), some operators
simply gave up on repairing their clusters due to the difficulties involved in
completing the operation successfully without impacting SLAs.
+The main problems encountered during repairs were:
+
+* A high number of pending compactions and SSTables on disk
+* Repairs taking longer than the tombstones GC grace period
+* High cluster load due to repair pressure
+* Blocked/never-ending repairs
+* A repair that isn't resumable in case of failure
+* vnodes made the operation very long and challenging to perform
+
+==== Reaper performs safe repairs
+
+Reaper was built to address those issues and make repairs as safe and reliable
as possible. It splits the repair operations into evenly sized subranges and
schedules them so that:
+
+* All nodes are kept busy repairing small units of data if possible
+* A single segment is running on a node at once
+* Segments lasting too long are terminated and re-scheduled
+* Failed segments get replayed in case of a transient failure
+* Pending compactions are monitored to pause segment scheduling, preventing
overload
+* Repairs can be paused
+
+The tool also supports incremental repair, which should be safely usable
starting with Cassandra 4.0. Since Cassandra 3.0, Reaper can create segments
with several token ranges to reduce the overhead of vnodes on repairs. Such
ranges will be repaired in a single job by Cassandra as segments will only
contain ranges that are replicated on the same set of nodes.
+
+=== Reaper Features
+
+Reaper ships with a http://cassandra-reaper.io/docs/api/[REST
API,window=_blank], a command-line tool (spreaper) and a Web UI:
+
+image::blog/blog-post-reaper-anti-entropy-repair/image5.png[cluster view]
+
+It collects and displays runtime Cassandra metrics, running compactions and
ongoing streaming sessions:
+
+image::blog/blog-post-reaper-anti-entropy-repair/image6.png[node metrics]
+
+Reaper ships with a scheduler for recurring repairs but can also perform
on-demand one-off repairs:
+
+image::blog/blog-post-reaper-anti-entropy-repair/image7.png[scheduler]
+
+image::blog/blog-post-reaper-anti-entropy-repair/image4.png[repair]
+
+It's easy to install as a
http://cassandra-reaper.io/docs/download/install/[tarball,window=_blank], a
https://hub.docker.com/r/thelastpickle/cassandra-reaper/[Docker
container,window=_blank], or
https://cloudsmith.io/%7Ethelastpickle/repos/reaper/packages/[deb/rpm
packages,window=_blank] and can be deployed in various ways to accommodate your
http://cassandra-reaper.io/docs/usage/multi_dc_distributed/[cluster's
architecture,window=_blank]. A single Reaper instance is capable of managing
[...]
+
+image::blog/blog-post-reaper-anti-entropy-repair/image8.png[singlereaper
multidc]
+
+image::blog/blog-post-reaper-anti-entropy-repair/image3.png[multireaper
multidc]
+
+image::blog/blog-post-reaper-anti-entropy-repair/image2.png[ha reaper setup]
+
+If JMX is restricted to local access, Reaper can even be deployed as a sidecar:
+
+image::blog/blog-post-reaper-anti-entropy-repair/image1.png[reaper sidecar]
+
+Reaper also can listen and display live Cassandra’s emitted Diagnostic Events.
+
+In Cassandra 4.0 internal system “diagnostic events” have become available via
the work done in
https://issues.apache.org/jira/browse/CASSANDRA-12944[CASSANDRA-12944,window=_blank].
These allow us to observe internal Cassandra events, for example, in unit
tests, and with external tools. These diagnostic events provide operational
monitoring and troubleshooting beyond logs and metrics.
+
+Reaper can use Postgres and Cassandra itself as a storage backend for its data
and can repair all Cassandra versions since 1.2 up to the latest 4.0.
+
+To make Reaper more efficient, segment orchestration was recently revamped and
modernized. It opened for a long-awaited feature: fully concurrent repairs for
different keyspaces and tables.
+These changes also introduced a long-awaited feature by allowing fully
concurrent repairs for different keyspaces/tables.
+
+You can find more details on these changes in the
https://thelastpickle.com/blog/2021/02/22/reaper-for-apache-cassandra-2-2-release.html[2.2
release blog post,window=_blank].
+
+Note: the latest release is
https://github.com/thelastpickle/cassandra-reaper/releases/tag/2.3.1[2.3.1,window=_blank].
+
+=== Eager to try Reaper?
+
+Head over to the
http://cassandra-reaper.io/[cassandra-reaper.io,window=_blank] website, which
contains all information you'll need to get started, install Reaper and stop
worrying about repairs!
+
+This article by Alexander Dejanovski was previously published on
https://jaxenter.com/reaper-anti-entropy-174878.html[JAXEnter.com,window=_blank].
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