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HBase Administration Cookbook

You're reading from  HBase Administration Cookbook

Product type Book
Published in Aug 2012
Publisher Packt
ISBN-13 9781849517140
Pages 332 pages
Edition 1st Edition
Languages
Author (1):
Yifeng Jiang Yifeng Jiang
Profile icon Yifeng Jiang

Table of Contents (16) Chapters

HBase Administration Cookbook
Credits
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
Setting Up HBase Cluster Data Migration Using Administration Tools Backing Up and Restoring HBase Data Monitoring and Diagnosis Maintenance and Security Troubleshooting Basic Performance Tuning Advanced Configurations and Tuning

WAL tool—manually splitting and dumping WALs


An HBase edit will first be written to a region server's Write Ahead Log (WAL). After the log is written successfully, MemStore of the region server will be updated. As WAL is a sequence file on HDFS, it will be automatically replicated to the two other DataNode servers by default, so that a single region server crash will not cause a loss of the data stored on it.

As WAL is shared by all regions deployed on the region server, the WAL needs to first be split so that it can be replayed on each relative region, in order to recover from a region server crash. HBase handles region server failover automatically by using this algorithm.

HBase has a WAL tool providing manual WAL splitting and dumping facilities. We will describe how to use this tool in this recipe.

Getting ready

We will need to put some data into an HBase table to have HBase generate WAL files for our demonstration. Again, we will use the hly_temp table in this recipe. We will put the...

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