Introduction: Installation Shapes Everything That Follows
Few would argue that the initial installation of Splunk is an important task, but everyone may not understand the breadth and depth of this meaning.
A clean, secure, and properly sized installation forms the foundation for stable and performant data ingestion and search, as well as the future scalability of Splunk. Mistakes or even failure to optimize at this step can lead to performance bottlenecks, security gaps, and engineering remediation later.
Prior to installation of Splunk, an organization should envision the future capabilities and performance of a mature Splunk environment. Having a complete vision of this future end state is crucial when it comes to building and executing the roadmap needed to arrive at the destination of full Splunk maturity.
This post outlines the key technical decisions, configurations, and validation steps needed to get your Splunk environment installed correctly.
Pre-Installation Requirements
Before installing Splunk, confirm that your infrastructure meets core system requirements:
- CPU: At least 4 cores for small environments; 12+ recommended for production
- Memory: Minimum 8 GB for trial use; 12–16 GB or more for production
- Storage: Fast, local SSDs preferred; at least 300 GB for production deployments
- Operating System: 64-bit Linux (preferred) or Windows Server, current versions supported
- Networking:
- Ensure open ports such as 8000 (Splunk Web), 8089 (management), 9997 (forwarders)
- Validate DNS resolution and hostname consistency across nodes
- Virtual Environments: Always reserve the resources for Splunk. Merely “allocating” the compute and memory resources for Splunk can result in significant problems in operating the software.
Installation Options & Deployment Models
There are three primary options for getting started. Choose one of these based on your data volume, IT resources, and growth expectations.
Single-Server Install
For proof-of-concept, small teams or app development, install Splunk Enterprise on a single server. This includes indexer, search head, and web UI all in one.
Most environments should have one of these, if nothing else for testing and development of apps.
Distributed Deployment
Use separate nodes for indexers, search heads, and heavy forwarders. This model scales better and offers faster performance, fault tolerance, and disaster recovery.
Splunk Cloud
For managed infrastructure, Splunk Cloud handles hosting and scaling. You manage data onboarding, apps, and configurations through a federated or dedicated search head. For teams that lack personnel trained to manage IT hardware, this selection is recommended.
'As You Go' Essentials
Build a network/architectural diagram of your Splunk environment!. Include the following components:
- Splunk Management Instances (Cluster Manager, Deployer, Deployment Server, License Manager)
- Splunk Functionality Tiers (Search, Index, Forwarder/Input)
- Critical Forwarders (large syslog Forwarders, IF/HF layer, HEC layer, DB Connect, etc)
- Open ports and the direction of communication
- Firewalls
- Hostnames/IPs
Build this document starting on day 1 of initial Splunk installation and keep it up to date as needed.
Learn/Use btool! While not absolutely necessary, this tool can be used to validate each step of the configuration process, plus it forces the user/administrator to learn this essential tool that ships with the Splunk software.
Securing a New Splunk Installation
After installation, the team should through these critical setup tasks:
- Set strong admin credentials during first login (Pro tip: Always use “admin” for the global admin name, and consider the implications of having a unique vs the same admin password for every Splunk instance, especially in a large/distributed environment)
- Utilize Base Configurations Don’t configure anything in $SPLUNK_HOME/etc/system/local! (remember that most CLI commands which configure Splunk put the resulting config in etc/system/local) Instead, use a more descriptive app, like orgName_myApp_inputs, or orgName_myApp_props, or orgName_indexes, for example. This allows for logical and practical separation of configurations, and it works quite well from a code versioning perspective. Also note that this allows you to enable/disable entire apps, a useful troubleshooting tool.
- Define index locations and ensure permissions allow Splunk AND ONLY Splunk to write data
- Verify service startup using CLI or service managers (systemctl, splunk status)
- Run a test search like index=_internal | head 10 to confirm data visibility
- Install and configure the Monitoring Console This is essential when it comes to monitoring and troubleshooting a splunk environment
These steps confirm that Splunk is functional and ready to ingest external data.
The following items should be reviewed before the Splunk environment is marked for production. These settings are difficult to change once a Splunk environment becomes operational, while having a large impact on how Splunk operates in your environment.
- FIPS Mode can only be enabled prior to the first start of any Splunk instance. This setting enables the platform to run on highly secure environments
- Admin user/password resets (as in you lost/forgot the password or even the username, in the event that you changed it from “admin”) require access to the file system and a restart of Splunk
- Changes to the location of Indexed Data, or $SPLUNK_DB require stopping Splunk, then copying the data to the new location along with changing multiple configurations to point to the new location, then restarting Splunk. In a large environment, copying the data can take a long time.
Common Installation Challenges & How to Solve Them
Problem | Solution |
|---|---|
Services fail to start | Check user and file/directory permissions, check disk space |
Ingest paths are misconfigured | Validate indexing paths in indexes.conf and corresponding permissions; run btool |
Splunk Web not accessible
| Confirm port 8000 is open and not being used or restricted |
Forwarders not connecting
| Verify port 9997 is open, and validate network routes from forwarders to indexers |
Storage fills too fast
| On the SH, if dispatch directory is full then either increase disk space or address the retention of alerts/search jobs which may be causing the disk pressure; on the IDX, ensure retention along with SF/RF are set in accordance with your needs and storage capacity, and examine your incoming data by source/sourcetype to ensure you are ingesting only what you need to ingest |
How Installation Affects Long-Term Outcomes
A properly planned and installed Splunk environment will:
- Perform searches faster by avoiding file system or memory constraints
- Support clean onboarding and searching of new data sources without need to work around the environment
- Scale predictably (planning is key for this!) as users, data, and apps grow
- Enable integrations with minimal troubleshooting
- Support admin efforts by minimizing early missteps and expediting potential troubleshooting later (documentation along with following best practices enables this!)
Good installation hygiene sets the tone for every phase that follows.
Next Steps for a Successful Start
- Complete a post-installation checklist (run through your backup/recovery process, and run a perfect Health Check from the Monitoring Console)
- Set up basic dashboards for internal Splunk metrics (ITSI has a great content pack for monitoring all layers of a Splunk environment!)
- Start onboarding key data sources—firewall logs, authentication, or endpoint data
- Keep your documentation up to date! (Splunk network/architecture diagram, service accounts, data/alert inventory)
- Maintain adherence to best practices for search/ingestion optimization, and implement the concept of CIM (even if a Splunk data model does not match!)
Start Strong with Expert Installation Support
A secure, scalable Splunk install isn’t just a technical step—it’s the foundation for everything your team wants to build. Let Presidio help ensure you’re getting it right from the beginning.
