Installing Apache Cassandra

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Magic Collaboration Studio uses Apache Cassandra - an open source NoSQL distributed database. So before installing Magic Collaboration Studio, you have to install Apache Cassandra as described below.

To install Apache Cassandra

1. Install Apache Cassandra by executing the install_cassandra<version_number>_<os_version>.sh installation script.

   Example

   sudo ./install_cassandra4x_centos_rhel_7.sh

   The script downloads and installs necessary packages, Cassandra and the Cassandra tools from the Apache Software Foundation repository, and creates the necessary firewall rules to allow proper operation both for a single node or a cluster installation. OpenJDK 8 will be installed with other packages, if you cannot use OpenJDK 8, you can install Oracle Java 8u202 instead. For instructions on how to do that, see Installing Oracle Java (optional). You can switch your setup to use OpenJDK 11 with Cassandra 4 also.

2. Start Apache Cassandra by executing the following command:

   sudo systemctl start cassandra

3. Check if Apache Cassandra is running by executing the following command:

   nodetool status

   If Apache Cassandra is running, you should receive the output displayed below. If the service is fully operational, the first 2 characters of the last line are "UN", indicating that the node status is Up, and its state is Normal.

   Datacenter: datacenter1
   =======================
   Status=Up/Down
   |/ State=Normal/Leaving/Joining/Moving
   --  Address    Load       Tokens   Owns (effective)  Host ID                               Rack
   UN  127.0.0.1  128.4 KB   256      100.0%            ea3f99eb-c4ad-4d13-95a1-80aec71b750f  rack1

   Wait for a few minutes until Cassandra starts for the first time before checking if it is running. If Cassandra has not started yet, you will get the error: "No nodes present in the cluster. Has this node finished starting up?" This means that you need to give Cassandra more time to start.

4. If Apache Cassandra is not running or if you used installation options other than the one described in this chapter, optionally configure Apache Cassandra.

When the installation is complete, perform the mandatory post-installation steps described in the next section.

Mandatory post-installation steps

After installing Cassandra, perform the following configuration changes:

• If you want to change the amount of RAM used by Cassandra, In the jvm-server.options file, uncomment the -Xms4G and -Xmx4g properties and specify their values. By default, Cassandra uses not more than 8 GB of RAM.
• In the jvm11-server.options and jvm8-server.options files, comment all lines from"### CMS Settings" to "### G1 Settings".

• In the jvm11-server.options and jvm8-server.options files, uncomment the following lines:

  #-XX:+UseG1GC
  #-XX:MaxGCPauseMillis=500

• In the jvm11-server.options and jvm8-server.options files, uncomment the following lines and set the values to the physical CPU core count (the values of both parameters should be the same):

  #-XX:ParallelGCThreads=16
  #-XX:ConcGCThreads=16

• In the jvm8-server.options file, comment all lines from "### GC logging options" to the end of the file.

• Synchronize CPU clocks on all Cassandra cluster nodes. Otherwise, you may encounter issues when creating an empty Cassandra cluster.

• When using cqlsh, use Python 3.6.0 or a later version. Python 2.7 series is no longer supported.
• In the logback.xml file, comment the "<appender-ref ref="ASYNCDEBUGLOG" />" line. This will increase Cassandra's performance by disabling the debug log.

Configuring Apache Cassandra (optional)

If you used other installation options and not the provided script or if Apache Cassandra does not start, configure it as described below.

To configure Apache Cassandra

1. Edit the cassandra.yaml file by executing the following command:

   sudo nano /etc/cassandra/default.conf/cassandra.yaml

2. Find the following parameters related to the Cassandra node IP address and communication settings, and change them as shown below:

   Example

   seeds: "192.168.130.10"
   listen_address: 192.168.130.10
   broadcast_rpc_address: 192.168.130.10
   rpc_address: 0.0.0.0

   • seeds - a comma-delimited list containing all of the seeds in the Cassandra cluster. Since our cluster consists of a single node, it contains only one entry - our IP address.
   • listen address - the IP address that Cassandra uses to listen for connections.
   • broadcast_rcp_address - the IP address used to broadcast to other Cassandra nodes in the cluster. This parameter may be commented. In such case, remove "#" and make sure there are no leading spaces.
   • rcp_address - when set to to 0.0.0.0, Cassandra listens to rpc requests on all interfaces.

3. Find the following parameters that control thresholds to ensure that the data being sent is processed properly, and change them as shown below:
   

   Example

   commitlog_segment_size_in_mb: 192
   read_request_timeout_in_ms: 1800000
   range_request_timeout_in_ms: 1800000
   write_request_timeout_in_ms: 1800000
   cas_contention_timeout_in_ms: 1000
   truncate_request_timeout_in_ms: 1800000
   request_timeout_in_ms: 1800000
   batch_size_warn_threshold_in_kb: 3000
   batch_size_fail_threshold_in_kb: 5000

4. To ensure that the default commit log size is 8GB (recommended), uncomment the commitlog_total_space_in_mb parameter as show as below.
   

   Example

   commitlog_total_space_in_mb: 8192

   Ensure that the partition where the commit log is installed has enough space to accommodate a commit log of 8GB.

5. To point the data to the appropriate locations, find the following parameters and change them as shown below:
   

   Example

   data_file_directories:
   - /data/data
   commitlog_directory: /logs/commitlog
   hints_directory: /data/hints
   saved_caches_directory: /data/saved_caches

6. Start Apache Cassandra by executing the following command:

   sudo systemctl start cassandra

7. Check if Apache Cassandra is running by executing the following command:

   nodetool status

   If Apache Cassandra is running, you should receive the output displayed below. If the service is fully operational, the first 2 characters of the last line are "UN", indicating that the node status is Up, and its state is Normal.

   Example

   Datacenter: datacenter1
   =======================
   Status=Up/Down
   |/ State=Normal/Leaving/Joining/Moving
   --  Address    Load       Tokens   Owns (effective)  Host ID                               Rack
   UN  127.0.0.1  128.4 KB   256      100.0%            ea3f99eb-c4ad-4d13-95a1-80aec71b750f  rack1

Tuning Linux to improve Apache Cassandra performance

To improve Apache Cassandra performance

1. Open the sysctl.conf file by executing the following command:

   sudo nano /etc/sysctl.conf

2. To configure the TCP settings, add the following tuning parameters to the file:

   Example

   net.core.rmem_max=16777216
   net.core.wmem_max=16777216
   net.core.optmem_max=40960
   net.core.default_qdisc=fq
   net.core.somaxconn=4096
   net.ipv4.conf.all.arp_notify = 1
   net.ipv4.tcp_keepalive_time=60
   net.ipv4.tcp_keepalive_probes=3
   net.ipv4.tcp_keepalive_intvl=10
   net.ipv4.tcp_mtu_probing=1
   net.ipv4.tcp_rmem=4096 12582912 16777216 
   net.ipv4.tcp_wmem=4096 12582912 16777216 
   net.ipv4.tcp_max_syn_backlog=8096
   net.ipv4.tcp_slow_start_after_idle = 0
   net.ipv4.tcp_tw_reuse = 1 
   vm.max_map_count = 1048575
   vm.swappiness = 0
   vm.dirty_background_ratio=5
   vm.dirty_ratio=80
   vm.dirty_expire_centisecs = 12000

3. To apply the setting without rebooting, execute the following command:

   sudo sysctl -p

For more information about tuning Linux, see DSE 6.8 Administrator Guide.