tencent cloud

Overview

CDH (Cloudera's distribution, including Apache Hadoop) is one of the most popular Hadoop distributions in the industry. This document describes how to use the COSN storage service in a CDH environment to separate big data computing from storage.

Note：

COSN refers to the Hadoop-COS file system.

Currently, the support for big data modules by COSN is as follows:

Module	Supported	Service Module to Restart
YARN	Yes	NodeManager
Hive	Yes	HiveServer and HiveMetastore
Spark	Yes	NodeManager
Sqoop	Yes	NodeManager
Presto	Yes	HiveServer, HiveMetastore, and Presto
Flink	Yes	None
Impala	Yes	None
EMR	Yes	None
Self-built component	To be supported in the future	No
HBase	Not recommended	None

Versions

This example uses software versions as follows:

• CDH 5.16.1
• Hadoop 2.6.0

How to Use

Configuring storage environment

1. Log in to the CDH management page.
2. On the homepage, select Configuration > Service-Wide > Advanced as shown below:
   
3. Specify your COSN settings in the configuration snippet Cluster-wide Advanced Configuration Snippet(Safety Valve) for core-site.xml.

   <property>
   <name>fs.cosn.userinfo.secretId</name>
   <value>AK***</value>
   </property>
   <property>
   <name>fs.cosn.userinfo.secretKey</name>
   <value></value>
   </property>
   <property>
   <name>fs.cosn.impl</name>
   <value>org.apache.hadoop.fs.CosFileSystem</value>
   </property>
   <property>
   <name>fs.AbstractFileSystem.cosn.impl</name>
   <value>org.apache.hadoop.fs.CosN</value>
   </property>
   <property>
   <name>fs.cosn.bucket.region</name>
   <value>ap-shanghai</value>
   </property>
   

The following lists the required COSN settings (to be added to core-site.xml). For other settings, see Hadoop.

COSN Configuration Item	Value	Description
fs.cosn.userinfo.secretId	AKxxxx	API key information of the account
fs.cosn.userinfo.secretKey	Wpxxxx	API key information of the account
fs.cosn.bucket.region	ap-shanghai	Bucket region
fs.cosn.impl	org.apache.hadoop.fs.CosFileSystem	The implementation class of COSN for FileSystem, which is fixed at `org.apache.hadoop.fs.CosFileSystem`
fs.AbstractFileSystem.cosn.impl	org.apache.hadoop.fs.CosN	The implementation class of COSN for AbstractFileSystem, which is fixed at `org.apache.hadoop.fs.CosN`

4. Take action on your HDFS service by clicking. Now, the core-site.xml settings above will apply to servers in the cluster. 5. Place the latest SDK package of COSN in the path of the JAR package of the CDH HDFS service and replace the relevant information with the actual value as shown below:

cp hadoop-cos-2.7.3-shaded.jar /opt/cloudera/parcels/CDH-5.16.1-1.cdh5.16.1.p0.3/lib/hadoop-hdfs/

Note：

The SDK JAR file needs to be put in the same location on each server in the cluster.

Data migration

Use Hadoop Distcp to migrate your data from CDH HDFS to COSN. For details, see Migrating Data Between HDFS and COS.

Using COSN for big data suites

1. MapReduce

Directions

(1) Configure HDFS settings as instructed in Data migration and put the JAR file of the COSN SDK in the correct HDFS directory.
(2) On the CDH homepage, find YARN and restart the NodeManager service (recommended). You can choose not to restart it for the TeraGen command, but must restart it for the TeraSort command because of the internal business logic.

Sample

The example below shows TeraGen and TeraSort in Hadoop standard test:

hadoop jar ./hadoop-mapreduce-examples-2.7.3.jar teragen  -Dmapred.job.maps=500  -Dfs.cosn.upload.buffer=mapped_disk -Dfs.cosn.upload.buffer.size=-1 1099 cosn://examplebucket-1250000000/terasortv1/1k-input

hadoop jar ./hadoop-mapreduce-examples-2.7.3.jar terasort -Dmapred.max.split.size=134217728 -Dmapred.min.split.size=134217728 -Dfs.cosn.read.ahead.block.size=4194304 -Dfs.cosn.read.ahead.queue.size=32 cosn://examplebucket-1250000000/terasortv1/1k-input  cosn://examplebucket-1250000000/terasortv1/1k-output

Note：

cosn:// Replace the content behind schema` with your own bucket path

2. Hive

2.1 MR engine

Directions

(1) Configure HDFS settings as instructed in Data migration and put the JAR file of the COSN SDK in the correct HDFS directory.
(2) On the CDH homepage, find Hive and restart the HiveServer2 and HiveMetastore roles.

Sample

To query your actual business data, use the Hive command line to create a location as a partitioned table on CHDFS:

CREATE TABLE `report.report_o2o_pid_credit_detail_grant_daily`(
  `cal_dt` string,
  `change_time` string,
  `merchant_id` bigint,
  `store_id` bigint,
  `store_name` string,
  `wid` string,
  `member_id` bigint,
  `meber_card` string,
  `nickname` string,
  `name` string,
  `gender` string,
  `birthday` string,
  `city` string,
  `mobile` string,
  `credit_grant` bigint,
  `change_reason` string,
  `available_point` bigint,
  `date_time` string,
  `channel_type` bigint,
  `point_flow_id` bigint)
PARTITIONED BY (
  `topicdate` string)
ROW FORMAT SERDE
  'org.apache.hadoop.hive.ql.io.orc.OrcSerde'
STORED AS INPUTFORMAT
  'org.apache.hadoop.hive.ql.io.orc.OrcInputFormat'
    OUTPUTFORMAT
  'org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat'
LOCATION
  'cosn://examplebucket-1250000000/user/hive/warehouse/report.db/report_o2o_pid_credit_detail_grant_daily'
TBLPROPERTIES (
  'last_modified_by'='work',
  'last_modified_time'='1589310646',
  'transient_lastDdlTime'='1589310646')

Perform a SQL query:

select count(1) from report.report_o2o_pid_credit_detail_grant_daily;

The output is as shown below:

2.2 Tez engine

You need to import the COSN JAR file as part of a Tez tar.gz file. The following example uses apache-tez.0.8.5:

Directions

(1) Locate and decompress the Tez tar.gz file installed in the CDH cluster, e.g., /usr/local/service/tez/tez-0.8.5.tar.gz.
(2) Put the COSN JAR file in the resulting directory, and then compress it into a new tar.gz file.
(3) Upload this new file to the path as specified by tez.lib.uris, or simply replace the existing file with the same name.
(4) On the CDH homepage, find Hive and restart HiveServer and HiveMetaStore.

3. Spark

Directions

(1) Configure HDFS settings as instructed in Data migration and put the JAR file of the COSN SDK in the correct HDFS directory.
(2) Restart NodeManager.

Sample

The following takes the Spark example word count test conducted with COSN as an example.

spark-submit  --class org.apache.spark.examples.JavaWordCount --executor-memory 4g --executor-cores 4  ./spark-examples-1.6.0-cdh5.16.1-hadoop2.6.0-cdh5.16.1.jar cosn://examplebucket-1250000000/wordcount

The output is as shown below:

4. Sqoop

Directions

(1) Configure HDFS settings as instructed in Data migration and put the JAR file of the COSN SDK in the correct HDFS directory.

(2) Put the JAR file of the COSN SDK in the Sqoop directory, for example, /opt/cloudera/parcels/CDH-5.16.1-1.cdh5.16.1.p0.3/lib/sqoop/.

(3) Restart NodeManager.

Sample

For example, to export MySQL tables to COSN, refer to Import/Export of Relational Database and HDFS.

sqoop import --connect "jdbc:mysql://IP:PORT/mysql" --table sqoop_test --username root --password 123**  --target-dir cosn://examplebucket-1250000000/sqoop_test

The output is as shown below:

5. Presto

Directions

(1) Configure HDFS settings as instructed in Data migration and put the JAR file of the COSN SDK in the correct HDFS directory.
(2) Put the JAR file of the COSN SDK in the Presto directory, for example, /usr/local/services/cos_presto/plugin/hive-hadoop2.
(3) Presto does not load the gson-2...jar JAR file (only used for CHDFS) from Hadoop Common, so you need to manually put it into the presto directory, for example, /usr/local/services/cos_presto/ plugin/hive-hadoop2.
(4) Restart HiveServer, HiveMetaStore, and Presto.

Sample

The example below queries the COSN scheme table as a Hive-created location:

select * from cosn_test_table where bucket is not null limit 1;

Note：

cosn_test_table is a table with location as cosn scheme.

The output is as shown below: