Repository: hadoop Updated Branches: refs/heads/trunk f0cd90386 -> 0c7340f37
HDFS-8914. Document HA support in the HDFS HdfsDesign.md. Contributed by Lars Francke. Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/0c7340f3 Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/0c7340f3 Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/0c7340f3 Branch: refs/heads/trunk Commit: 0c7340f377f6663052be097ef58d60eee25f7334 Parents: f0cd903 Author: Haohui Mai <[email protected]> Authored: Sun Nov 22 16:10:27 2015 -0800 Committer: Haohui Mai <[email protected]> Committed: Sun Nov 22 16:10:27 2015 -0800 ---------------------------------------------------------------------- hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt | 3 +++ hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hadoop/blob/0c7340f3/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt index 106b569..41f5e7c 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt +++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt @@ -2337,6 +2337,9 @@ Release 2.8.0 - UNRELEASED HDFS-9443. Disabling HDFS client socket cache causes logging message printed to console for CLI commands. (Chris Nauroth via wheat9) + HDFS-8914. Document HA support in the HDFS HdfsDesign.md. + (Lars Francke via wheat9) + Release 2.7.3 - UNRELEASED INCOMPATIBLE CHANGES http://git-wip-us.apache.org/repos/asf/hadoop/blob/0c7340f3/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md index 4c0d44e..c779afc 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md +++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md @@ -186,7 +186,7 @@ It is possible that a block of data fetched from a DataNode arrives corrupted. T The FsImage and the EditLog are central data structures of HDFS. A corruption of these files can cause the HDFS instance to be non-functional. For this reason, the NameNode can be configured to support maintaining multiple copies of the FsImage and EditLog. Any update to either the FsImage or EditLog causes each of the FsImages and EditLogs to get updated synchronously. This synchronous updating of multiple copies of the FsImage and EditLog may degrade the rate of namespace transactions per second that a NameNode can support. However, this degradation is acceptable because even though HDFS applications are very data intensive in nature, they are not metadata intensive. When a NameNode restarts, it selects the latest consistent FsImage and EditLog to use. -The NameNode machine is a single point of failure for an HDFS cluster. If the NameNode machine fails, manual intervention is necessary. Currently, automatic restart and failover of the NameNode software to another machine is not supported. +Another option to increase resilience against failures is to enable High Availability using multiple NameNodes either with a [shared storage on NFS](./HDFSHighAvailabilityWithNFS.html) or using a [distributed edit log](./HDFSHighAvailabilityWithQJM.html) (called Journal). The latter is the recommended approach. ### Snapshots
