Configuring the Storage Policy for the Write-Ahead Log (WAL)
In CDH 5.7.0 and higher, you can configure the preferred HDFS storage policy for HBase's write-ahead log (WAL) replicas. This feature allows you to tune HBase's use of SSDs to your available resources and the demands of your workload.
- NONE: no preference about where the replicas are written.
- ONE_SSD: place one replica on SSD storage and the remaining replicas in default storage. This allows you to derive some benefit from SSD storage even if it is a scarce resource in your cluster.
- ALL_SSD: place all replicas on SSD storage.
Configuring the Storage Policy for WALs Using Cloudera Manager
Minimum Required Role: Full Administrator
- Go to the HBase service.
- Click the Configuration tab.
- Search for the property WAL HSM Storage Policy.
- Select your desired storage policy.
- Save your changes. Restart all HBase roles.
Configuring the Storage Policy for WALs Using the Command Line
<property> <name>hbase.wal.storage.policy</name> <value>NONE</value> <!--<value>ONE_SSD</value>--> <!--<value>ALL_SSD</value>--> </property>
Restart HBase. Changes will take effect for a given region during its next major compaction.