Improving Write Performance

true: The cached data is discarded. This parameter needs to be configured on the DataNode. You are advised to set it to true if data is repeatedly read only a few times, so that the cache can be used by other operations.
false: You are advised to set it to false if data is read repeatedly for many times to improve the read speed.

Scenario

Improve the HDFS write performance by modifying the HDFS attributes.

This section applies to MRS 3.x or later.

Procedure

Navigation path for setting parameters:

On FusionInsight Manager, choose Cluster > Name of the desired cluster > Services > HDFS > Configurations and select All Configurations. Enter a parameter name in the search box.

**Table 1** Parameters for improving HDFS write performance
Parameter	Description	Default Value
dfs.datanode.drop.cache.behind.reads	Specifies whether to enable a DataNode to automatically clear all data in the cache after the data in the cache is transferred to the client. true: The cached data is discarded. This parameter needs to be configured on the DataNode. You are advised to set it to true if data is repeatedly read only a few times, so that the cache can be used by other operations. false: You are advised to set it to false if data is read repeatedly for many times to improve the read speed. NOTE: This parameter is optional for improving write performance. You can configure it as needed.	false
dfs.client-write-packet-size	Specifies the size of the client write packet. When the HDFS client writes data to the DataNode, the data will be accumulated until a packet is generated. Then, the packet is transmitted over the network. This parameter specifies the size (unit: byte) of the data packet to be transmitted, which can be specified by each job. In the 10-Gigabit network, you can increase the value of this parameter to enhance the transmission throughput.	262144