Repository: hadoop Updated Branches: refs/heads/branch-3.0 83a4f92a3 -> 2a36b4b1e
HDFS-13063. Fix the incorrect spelling in HDFSHighAvailabilityWithQJM.md Signed-off-by: Akira Ajisaka <[email protected]> (cherry picked from commit eb2dd0868864da994612f1dd1452ea38d31f5e85) Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/2a36b4b1 Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/2a36b4b1 Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/2a36b4b1 Branch: refs/heads/branch-3.0 Commit: 2a36b4b1ed3f23483e762405a3e1627b7c8620c0 Parents: 83a4f92 Author: Jianfei Jiang <[email protected]> Authored: Thu Jan 25 15:27:28 2018 +0900 Committer: Akira Ajisaka <[email protected]> Committed: Thu Jan 25 15:31:45 2018 +0900 ---------------------------------------------------------------------- .../hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hadoop/blob/2a36b4b1/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md index 99bc8f0..b7fce98 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md +++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md @@ -49,7 +49,7 @@ Architecture In a typical HA cluster, two or more separate machines are configured as NameNodes. At any point in time, exactly one of the NameNodes is in an *Active* state, and the others are in a *Standby* state. The Active NameNode is responsible for all client operations in the cluster, while the Standbys are simply acting as workers, maintaining enough state to provide a fast failover if necessary. -In order for the Standby node to keep its state synchronized with the Active node, both nodes communicate with a group of separate daemons called "JournalNodes" (JNs). When any namespace modification is performed by the Active node, it durably logs a record of the modification to a majority of these JNs. The Standby node is capable of reading the edits from the JNs, and is constantly watching them for changes to the edit log. As the Standby Node sees the edits, it applies them to its own namespace. In the event of a failover, the Standby will ensure that it has read all of the edits from the JounalNodes before promoting itself to the Active state. This ensures that the namespace state is fully synchronized before a failover occurs. +In order for the Standby node to keep its state synchronized with the Active node, both nodes communicate with a group of separate daemons called "JournalNodes" (JNs). When any namespace modification is performed by the Active node, it durably logs a record of the modification to a majority of these JNs. The Standby node is capable of reading the edits from the JNs, and is constantly watching them for changes to the edit log. As the Standby Node sees the edits, it applies them to its own namespace. In the event of a failover, the Standby will ensure that it has read all of the edits from the JournalNodes before promoting itself to the Active state. This ensures that the namespace state is fully synchronized before a failover occurs. In order to provide a fast failover, it is also necessary that the Standby node have up-to-date information regarding the location of blocks in the cluster. In order to achieve this, the DataNodes are configured with the location of all NameNodes, and send block location information and heartbeats to all. --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
