Kubernetes manages stateless Spark and Hive containers elastically on the compute nodes. Spark has native scheduler integration with Kubernetes. Hive, for legacy reasons, uses YARN scheduler on top of Kubernetes.
All access to MinIO object storage is via S3/SQL SELECT API. In addition to the compute nodes, MinIO containers are also managed by Kubernetes as stateful containers with local storage (JBOD/JBOF) mapped as persistent local volumes. This architecture enables multi-tenant MinIO, allowing isolation of data between customers.
MinIO also supports multi-cluster, multi-site federation similar to AWS regions and tiers. Using MinIO Information Lifecycle Management (ILM), you can configure data to be tiered between NVMe based hot storage, and HDD based warm storage. All data is encrypted with per-object key. Access Control and Identity Management between the tenants are managed by MinIO using OpenID Connect or Kerberos/LDAP/AD.
* Install Hortonworks Distribution using this [guide.](https://docs.hortonworks.com/HDPDocuments/Ambari-2.7.1.0/bk_ambari-installation/content/ch_Installing_Ambari.html)
* [Setup Ambari](https://docs.hortonworks.com/HDPDocuments/Ambari-2.7.1.0/bk_ambari-installation/content/set_up_the_ambari_server.html) which automatically sets up YARN
After successful installation navigate to the Ambari UI `http://<ambari-server>:8080/` and login using the default credentials: [**_username: admin, password: admin_**]
Let's take for example a set of 12 compute nodes with an aggregate memory of *1.2TiB*, we need to do following settings for optimal results. Add the following optimal entries for _core-site.xml_ to configure _s3a_ with **MinIO**. Most important options here are
mapreduce.fileoutputcommitter.algorithm.version=2 # Use the latest committer version
mapreduce.job.reduce.slowstart.completedmaps=0.99 # 99% map, then reduce
mapreduce.reduce.shuffle.input.buffer.percent=0.9 # Min % buffer in RAM
mapreduce.reduce.shuffle.merge.percent=0.9 # Minimum % merges in RAM
mapreduce.reduce.speculative=false # Disable speculation for reducing
mapreduce.task.io.sort.factor=999 # Threshold before writing to disk
mapreduce.task.sort.spill.percent=0.9 # Minimum % before spilling to disk
```
S3A is the connector to use S3 and other S3-compatible object stores such as MinIO. MapReduce workloads typically interact with object stores in the same way they do with HDFS. These workloads rely on HDFS atomic rename functionality to complete writing data to the datastore. Object storage operations are atomic by nature and they do not require/implement rename API. The default S3A committer emulates renames through copy and delete APIs. This interaction pattern causes significant loss of performance because of the write amplification. *Netflix*, for example, developed two new staging committers - the Directory staging committer and the Partitioned staging committer - to take full advantage of native object storage operations. These committers do not require rename operation. The two staging committers were evaluated, along with another new addition called the Magic committer for benchmarking.
It was found that the directory staging committer was the fastest among the three, S3A connector should be configured with the following parameters for optimal results:
For more information about these options please visit [https://www.cloudera.com/documentation/enterprise/5-11-x/topics/admin_hive_on_s3_tuning.html](https://www.cloudera.com/documentation/enterprise/5-11-x/topics/admin_hive_on_s3_tuning.html)
After installing Hive, Hadoop and Spark successfully, we can now proceed to run some sample applications to see if they are configured appropriately. We can use Spark Pi and Spark WordCount programs to validate our Spark installation. We can also explore how to run Spark jobs from the command line and Spark shell.
### **4.1 Spark Pi**
Test the Spark installation by running the following compute intensive example, which calculates pi by “throwing darts” at a circle. The program generates points in the unit square ((0,0) to (1,1)) and counts how many points fall within the unit circle within the square. The result approximates pi.
The job should produce an output as shown below. Note the value of pi in the output.
```
17/03/22 23:21:10 INFO DAGScheduler: Job 0 finished: reduce at SparkPi.scala:38, took 1.302805 s
Pi is roughly 3.1445191445191445
```
Job status can also be viewed in a browser by navigating to the YARN ResourceManager Web UI and clicking on job history server information.
### **4.2 WordCount**
WordCount is a simple program that counts how often a word occurs in a text file. The code builds a dataset of (String, Int) pairs called counts, and saves the dataset to a file.
The following example submits WordCount code to the Scala shell. Select an input file for the Spark WordCount example. We can use any text file as input.
