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Posted to common-commits@hadoop.apache.org by ha...@apache.org on 2018/01/03 21:32:00 UTC
[28/50] [abbrv] hadoop git commit: HDFS-12351. Explicitly describe
the minimal number of DataNodes required to support an EC policy in EC
document.. Contributed by Hanisha Koneru.
HDFS-12351. Explicitly describe the minimal number of DataNodes required to support an EC policy in EC document.. Contributed by Hanisha Koneru.
Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo
Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/b4d11337
Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/b4d11337
Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/b4d11337
Branch: refs/heads/YARN-1011
Commit: b4d11337c9271f29dd403d2393812f2ab6f35b35
Parents: dfe0cd8
Author: Arpit Agarwal <ar...@apache.org>
Authored: Tue Jan 2 12:54:40 2018 -0800
Committer: Arpit Agarwal <ar...@apache.org>
Committed: Tue Jan 2 12:54:40 2018 -0800
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.../hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md | 4 ++++
1 file changed, 4 insertions(+)
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http://git-wip-us.apache.org/repos/asf/hadoop/blob/b4d11337/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
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diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
index 4459c94..60fd3ab 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
@@ -99,6 +99,10 @@ Deployment
Encoding and decoding work consumes additional CPU on both HDFS clients and DataNodes.
+ Erasure coding requires a minimum of as many DataNodes in the cluster as
+ the configured EC stripe width. For EC policy RS (6,3), this means
+ a minimum of 9 DataNodes.
+
Erasure coded files are also spread across racks for rack fault-tolerance.
This means that when reading and writing striped files, most operations are off-rack.
Network bisection bandwidth is thus very important.
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