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Federated architecture best fits customers that execute high load (thousands of transactions per second or more) in their gateways.

The cell environment implements the federated architecture by distributing DPOD's Store and DPOD's agents across different federated servers.

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• Cell Manager - a DPOD server (usually virtual) that manages all Federated Cell Members (FCMs), as well as providing central DPOD services such as the Web Console, reports, alerts, resource monitoring, etc.
• Federated Cell Members (FCMs) - DPOD servers (usually physical with very fast local storage) that include Store data nodes and agents (Syslog and WS-M) for collecting, parsing and storing data.

The cell environment does not replicate any data between the members, so adding more members will not provide any HA / DR capabilities.

The following diagram describes the cell environment:

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1. Before installing a cell environment, make sure to complete the sizing process with IBM Support Team to get recommendations for the hardware and architecture suitable for your requirements.
2. DPOD cell manager and federated cell members must be of the same version.
3. DPOD cell manager is usually virtual and can be installed in both Appliance Mode or Non-Appliance Mode with Medium Load architecture type, as detailed in the Hardware and Software Requirements.
4. DPOD federated cell members (FCMs) can be one of the following:
   1. Physical servers installed in Non-appliance Mode (based on RHEL) with High_20dv architecture type, as detailed in the Hardware and Software Requirements.
      Physical servers are used when the cell is required to process high transactions per second (TPS) load.
   2. Virtual servers installed in Non-appliance Mode with Medium architecture type or higher, as detailed in the Hardware and Software Requirements.
      Virtual servers are used when the cell is required to process moderate transactions per second (TPS) load, or when the cell is part of a non-production environment where the production cell uses physical servers (to keep environments architecture similar).
5. All DPOD cell members must be identical - only physical or only virtual (cannot mix physical and virtual cell members in the same cell), and with the same resources (CPUs, RAM, disk type and storage capacity).
6. Physical federated cell members with 4 CPU sockets and NVMe disks require special disks and mount points configuration to ensure performance. See Configuring Cell Members with 4 CPU Sockets and NVMe Disks.
7. Each cell component (manager / FCM) should have two network interfaces:
   
   1. Internal network interface - dedicated for DPOD inter-communication between the cell components.
   2. External network interface - for communicating with the rest of the network. This includes users accessing the DPOD Web Console (on the cell manager), communication between DPOD and the Monitored Gateways, communication with DNS, NTP, SMTP, LDAP, and anything else on the network.
   3. This design was driven by customer requirements and allows separation between the two types of communications, which may be used to enhance the security (e.g.: deny end-users from being able to access the inter-cell communication).
   4. We recommend that all the internal network interfaces have IP addresses which belong to a single subnet (the internal subnet), and also all the external network interfaces have IP addresses which belong to a single subnet (the external subnet). Having an internal subnet that is different from the external subnet makes it easier to configure the servers without using static routing and easier to configure the network firewall rules.
   5. A diagram demonstrating this is available in Firewall Rules Requirements for DPOD Cell Environment.
8. Network rules should be defined as detailed in Firewall Rules Requirements for DPOD Cell Environment.

Cell Manager Installation

Prerequisites

• Make sure to meet the prerequisites listed at the top of this page.
• For Non-appliance Mode, follow the procedure: Prepare Pre-Installed Operating System.

DPOD Installation

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• For Non-appliance Mode, follow the procedure: Non-Appliance Installation.
  For

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• Appliance Mode, follow the procedure: 

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• Appliance Installation.
  During installation, when prompted to choose the data disk type (SSD / non SSD), choose the cell members disk type (should be SSD) instead of the cell manager disk type.
  During installation, when prompted to choose the IP address for the Web Console, choose the IP address of the external network interface

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Federated Cell Member Installation

The following section describes the installation process of a single Federated Cell Member (FCM). Please repeat the procedure for every FCM installation.

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• Make sure to meet the prerequisites listed at the top of this page.
• Follow the procedure: Prepare Pre-Installed Operating System.
• Physical servers should use RHEL as the operating system (and not CentOS).
• The cell member server should contain disks according to the recommendations made in the sizing process with IBM Support Team, which includes disks for OS, install, and data (one for /data and 6 to 9 additional disks for /data2/3/4...).
• Physical federated cell members with 4 CPU sockets and NVMe disks require special disks and mount points configuration to ensure performance. See Configuring Cell Members with 4 CPU Sockets and NVMe Disks

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DPOD Installation

• Physical servers should use RHEL as the operating system (and not CentOS).
• Use Non-appliance Mode and follow the procedure: Non-Appliance Installation
  During installation, the four-letter Installation Environment Name should be identical to the one that was chosen during the Cell Manager installation.
  During installation, when prompted to choose the IP address for the Web Console, choose the IP address of the external network interface.
• Once installation is done, execute the following operating system performance optimization command and reboot the server:

/app/scripts/tune-os-parameters.sh
reboot

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• Make sure httpd service is running and can be restarted successfully. If an error is displayed during the service restart, please see if the following information helps in resolving it: https://access.redhat.com/solutions/1180103

systemctl restart httpd

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In order to federate and configure the cell member, run the following script in the cell manager, once per cell member.

Important: The script should be executed using the OS root user, and also requires remote root access over SSH from the cell manager to the cell member.

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The script writes two log files - one in the cell manager and one in the cell member. The log file names are mentioned in the script's output.
In case of a failure, the script will try to rollback the configuration changes it made, so the problem can be fixed before rerunning it again.
If the rollback fails, and the cell member services do not start successfully, it might be required to uninstall DPOD from the cell member, reinstall and federate it again.

Updating Configuration for Physical Federated Cell Members with 4 CPU Sockets and NVMe Disks

Note: If the cell member server does not have 4 CPU sockets or does not have NVMe disks - skip this step.

To update the service files, execute the following commands:

sed -i 's#/usr/bin/numactl --membind=1 --cpunodebind=1#/usr/bin/numactl --membind=2 --cpunodebind=2#g' /etc/init.d/MonTier-es-raw-trans-Node-3
sed -i 's#/usr/bin/numactl --membind=1 --cpunodebind=1#/usr/bin/numactl --membind=3 --cpunodebind=3#g' /etc/init.d/MonTier-es-raw-trans-Node-4

To verify the NUMA configuration for all services, execute the following command:

grep numactl /etc/init.d/*

Updating Configuration for Federated Cell Members with at least 384GB RAM

Note: If the cell member server has less than 384GB RAM - skip this step.

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Reboot the Federated Cell Member

Execute the following command to reboot the cell member:

sed -i 's/^NODE_HEAP_SIZE=.*/NODE_HEAP_SIZE="64G"/g' /etc/init.d/MonTier-es-raw-trans-Node-2
sed -i 's/^NODE_HEAP_SIZE=.*/NODE_HEAP_SIZE="64G"/g' /etc/init.d/MonTier-es-raw-trans-Node-3
sed -i 's/^NODE_HEAP_SIZE=.*/NODE_HEAP_SIZE="64G"/g' /etc/init.d/MonTier-es-raw-trans-Node-4

Restarting Services of the Federated Cell Member

Stop all the application services using app-util.sh → option 2 (stop all)

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reboot

Cell Member Federation Verification

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