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''Auto-generated from the uploaded PDF [[:File:Nagios_XI_Cluster_Setup_Checklist-Updated.pdf|Nagios_XI_Cluster_Setup_Checklist-Updated.pdf]]. This is an extracted-text rendering for searchability; see the original PDF for exact formatting, diagrams, tables, and images.''

<pre>
<nowiki>
Nagios XI Cluster Setup Checklist with
DRBD and Pacemaker
Pre-Deployment Checklist

Ensure the environment and system prerequisites are in place before proceeding with
clustering. This sets a stable foundation for DRBD and Pacemaker configuration.

Step Task Details
1 System Prep Same OS (e.g.,
RHEL/CentOS/Ubuntu),
updates applied
2 Hostnames Unique FQDNs (e.g., `nagios-
node1`, `nagios-node2`)
3 DNS or `/etc/hosts` Proper name resolution
between nodes
4 NTP Time sync via NTP on both
nodes
5 Static IPs Two IPs (one per node) +
one VIP reserved
6 Partition for DRBD Dedicated block device (e.g.,
`/dev/sdb1`) on both nodes
7 Open Firewall Ports for MySQL, HTTP(S),
DRBD, Corosync

DRBD Storage Setup

Configure the Distributed Replicated Block Device (DRBD) to replicate Nagios XI data
storage between nodes for high availability.

Step Task Details
1 Install DRBD `yum install drbd-utils` or
`apt install drbd-utils`
2 Create DRBD config `/etc/drbd.d/nagios.res`
defining resource
3 Init DRBD meta `drbdadm create-md
nagios`
4 Bring up DRBD `drbdadm up nagios`

5 Make one primary `drbdadm -- --overwrite-
data-of-peer primary
nagios`
6 Format DRBD `mkfs.ext4 /dev/drbd0`
7 Mount DRBD Mount at
`/usr/local/nagiosxi` or
`/opt/nagios`
8 Sync Nagios XI data Install on node1, sync to
DRBD volume

Nagios XI Setup on DRBD

Place Nagios XI data and configuration files on the DRBD shared storage to ensure
persistence and synchronization between nodes.

Step Task Details
1 Move Nagios XI to DRBD Move `/usr/local/nagiosxi`
to DRBD mount
2 Symlink or remount Ensure Nagios, MySQL, and
logs use shared storage
3 Sync MySQL Data Ensure MySQL data also
resides on DRBD

Corosync & Pacemaker Cluster Setup

Set up the core cluster software that manages failover, monitoring, and service
orchestration.

Step Task Details
1 Install Components `pcs`, `corosync`,
`pacemaker`, `fence-agents`
2 Enable pcsd `systemctl enable pcsd --
now`
3 Set hacluster password `echo mypass | passwd
hacluster --stdin`
4 Authenticate Nodes `pcs cluster auth nagios-
node1 nagios-node2`
5 Create Cluster `pcs cluster setup --name
nagios-cluster nagios-node1
nagios-node2`
6 Start & Enable Cluster `pcs cluster start --all` and
`pcs cluster enable --all`

Pacemaker Resources (in Order)

Define and order the cluster-managed resources to control DRBD, filesystem, VIP, and
services in a consistent failover pattern.

Step Task Details
1 DRBD resource `ocf:linbit:drbd` with
master/slave configuration
2 Filesystem `ocf:heartbeat:Filesystem`
for DRBD mount
3 Virtual IP (VIP) `ocf:heartbeat:IPaddr2` on
shared subnet
4 Nagios XI service Custom `systemd:nagiosxi`
script or service group
5 MySQL/MariaDB Optional: managed as
cluster resource if HA DB
6 Colocation Ensure filesystem and VIP
before Nagios starts
7 Ordering DRBD → Filesystem → VIP
→ Nagios services

Failover & Health Check
Test and verify failover functionality and ensure all services remain operational and data
remains consistent.

Step Task Details
1 Manual Failover Test Stop node1, ensure node2 takes over
services
2 VIP Test Ping/telnet to VIP for Nagios web, DB

3 Log Checks `pcs status`, `journalctl -xe`, DRBD logs

4 Service State Ensure NagiosXI, MySQL, npcd, crond
running
5 External Monitoring Verify notifications still trigger during
failover

Security & Hardening
Secure your cluster environment and restrict unauthorized access to critical resources and
ports.

Step Task Details
1 Limit DRBD port Allow only internal IPs on
port 7788
2 Secure `pcs` user Limit `hacluster` access via
firewall
3 Enable STONITH For production
environments only
4 Monitor Logs Integrate logs with
centralized syslog server

Post-Setup and Documentation
Document the setup process, ensure proper backup procedures, and integrate the cluster
with monitoring and alerting systems.

Step Task Details
1 Update SOP Create documentation for
failover, failback
2 Monitoring Integration Add checks for VIP, DB,
DRBD status in Nagios
3 Test Restore Test full restore from
backup with DRBD volume
4 Backup Plan Configure daily backups of
Nagios DB and configs

Fallback Plan (Manual Recovery Procedures)
In the event of a complete cluster failure or unexpected behavior not handled by automatic
failover, follow the steps below to restore Nagios XI operations manually.

1. Assess Cluster State

- Run `pcs status` and `drbdadm status` on both nodes.

- Check system logs: `journalctl -xe`, `/var/log/messages`, DRBD logs.

2. Manual DRBD Promotion

If DRBD resource fails to auto-promote:

3. Force Service Start on One Node

Manually start Nagios XI and dependencies:

Confirm that services are running and accessible.

4. Force VIP Assignment

If the virtual IP (VIP) is not assigned

5. Check Application Functionality

- Confirm Nagios web interface loads from VIP.

- Verify alerting and checks are functioning.

6. Isolate Problem Node

- If one node is unstable, isolate it:

- Avoid split-brain scenarios.

7. Plan Rejoin or Rebuild

- Once stable, re-integrate the failed node using `pcs` or rebuild from backup.

8. Log and Review

- Record issue, recovery actions, and outcomes.

- Update SOP/documentation.
</nowiki>
</pre>

Nagios XI Cluster Setup Checklist-Updated - Revision history

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