Technology · head to head
etcd vs Nagios XI
etcd
Technology
A distributed key-value store using Raft consensus, built for cluster coordination rather than application data.
- From
- On request
- Rated
- -
Nagios XI
Technology
Enterprise-grade monitoring solution with advanced visualization and reporting
- From
- Free
- Rated
- -
The short version
- Only Nagios XI has a free tier, so it costs nothing to try first.
- Each has a real cost: etcd it is sized for coordination data, not application data: the default backend quota is 2 GB and 8 GB is the documented recommended maximum, and exceeding it puts the cluster into a NOSPACE alarm where it accepts no writes until an operator compacts, defragments and clears the alarm by hand.; Nagios XI free Edition caps at 7 nodes or 100 services, whichever limit is hit first
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which etcd and Nagios XI actually diverge.
Identical on both: platforms (Web), user rating (Not yet rated), category (Technology).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in etcd
- Raft consensus
- Linearizable reads
- Transactions
- Leases
- Watches
- MVCC revision history
- Role-based access control
- Snapshot backup and restore
Only in Nagios XI
Nothing recorded that etcd does not also cover.
What people use each for
The jobs each tool is most often brought in to do.
etcd
- Storing Kubernetes cluster state, which is what the overwhelming majority of etcd deployments are doingnot Nagios XI
- Leader election and distributed locking in a home-grown scheduler or control plane, using leases and transactionsnot Nagios XI
- Service discovery and dynamic configuration where readers need to be notified of changes rather than poll for themnot Nagios XI
- Coordinating failover in a clustered database, as Patroni does for PostgreSQLnot Nagios XI
Nagios XI
- Monitoring servers, networks, and IoT devices for status changesnot etcd
- Detecting infrastructure problems before they cause outagesnot etcd
- Creating customizable dashboards for real-time IT visibilitynot etcd
- Tracking SLA compliance and generating capacity planning reportsnot etcd
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
etcd
- It is sized for coordination data, not application data: the default backend quota is 2 GB and 8 GB is the documented recommended maximum, and exceeding it puts the cluster into a NOSPACE alarm where it accepts no writes until an operator compacts, defragments and clears the alarm by hand.
- Every write is replicated and fsynced before acknowledgement, so cluster performance is bounded by the slowest disk in it; a member on network-attached storage with high fsync latency causes leader elections and cluster-wide latency spikes that look like network problems and are not.
- Adding members increases availability but reduces write throughput, because each write must reach a larger quorum; you run three or five members for fault tolerance, and increasing capacity means faster hardware rather than more nodes.
- There is no sharding and no multi-tenancy, so isolating workloads means running separate clusters, each with its own quorum, certificates, backup schedule and upgrade path, and that operational multiplication is often unexpected.
- Running it yourself is a real job: periodic compaction and defragmentation, snapshot backups you have actually rehearsed restoring, and rotation of both peer and client TLS certificates, none of which happens automatically outside a managed Kubernetes service.
- Losing quorum is not self-healing; recovering a cluster that has lost a majority means restoring from a snapshot and accepting that everything written since that snapshot is gone, which makes backup frequency a data-loss budget decision rather than a routine setting.
Nagios XI
- Free Edition caps at 7 nodes or 100 services, whichever limit is hit first
- Standard Edition is licensed per node count, starting at $2,595 for 100 nodes and rising to $14,995 for 1,000 nodes
- Enterprise Edition, which adds capacity planning and SLA reporting, is sold as an add-on starting at $4,690 for 100 nodes on top of the base license
- Sitewide Edition for large distributed environments has no published price and requires contacting sales
Pricing, plan by plan
etcd
On requestNo published plan breakdown. See the etcd review.
Nagios XI
Free- Free EditionFree
- 7 nodes OR 100 services limit
- Self-supported only
- Standard 100-Node$2595/perpetual
- 100 nodes
- First year includes support and upgrades
- Standard 500-Node$8295/perpetual
- 500 nodes
- First year includes support and upgrades
- Standard 1000-Node$14995/perpetual
- 1,000 nodes
- First year includes support and upgrades
Which should you pick?
Questions people ask
- Is etcd or Nagios XI better?
- Neither clearly leads. etcd starts at On request and Nagios XI at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, etcd or Nagios XI?
- Nagios XI has a free tier; the other does not. Paid plans start at On request for etcd and Free for Nagios XI.
- Does etcd or Nagios XI run on more platforms?
- Both run on Web, so platform support will not decide this one for you.
- Can I use Nagios XI for free?
- Yes. Nagios XI has a free tier, so you can try it without paying. etcd starts at On request.
- What is etcd best used for?
- etcd is most often used for storing kubernetes cluster state, which is what the overwhelming majority of etcd deployments are doing, leader election and distributed locking in a home-grown scheduler or control plane, using leases and transactions, service discovery and dynamic configuration where readers need to be notified of changes rather than poll for them, coordinating failover in a clustered database, as patroni does for postgresql. Of those, storing kubernetes cluster state, which is what the overwhelming majority of etcd deployments are doing and leader election and distributed locking in a home-grown scheduler or control plane, using leases and transactions are not what Nagios XI is typically brought in for.
- What can etcd do that Nagios XI cannot?
- etcd covers Raft consensus, Linearizable reads, Transactions, Leases.
Answered from the vendors’ own pages
etcd: Can I use etcd as an application database?
No. It is designed for metadata and coordination, with a recommended maximum store size of around 8 GB, no sharding and a write path deliberately optimised for durability rather than throughput. Application data belongs in a database built for it.
Nagios XI: What is Nagios XI's pricing model?
Nagios XI uses perpetual licensing with one-time purchase costs based on node count, ranging from $2,595 for 100 nodes to $14,995 for 1,000 nodes.
Sourceetcd: How many members should a cluster have?
Three for most cases, five where you need to survive two simultaneous failures. Always an odd number, because an even-sized cluster gains no additional fault tolerance while making quorum harder to reach.
Nagios XI: Is there a free version of Nagios XI?
Yes, Nagios XI Free Edition is available at no cost with a limit of 7 nodes or 100 services, whichever is reached first.
Sourceetcd: What happens when the store fills up?
The cluster raises a NOSPACE alarm and stops accepting writes, becoming effectively read-only. Recovery requires compacting old revisions, defragmenting each member and then explicitly disarming the alarm, all done by an operator.
Nagios XI: What is included with Nagios XI licensing?
Initial licenses include one year of free version upgrades, up to 10 support cases, and support portal access. Each license permits three installations: production, backup/failover, and testing/development.
Sourceetcd: Why is my etcd cluster slow or unstable?
Almost always disk latency. Because every write is fsynced before acknowledgement, slow or shared storage causes heartbeat timeouts, leader elections and cascading latency. Local SSDs with low fsync latency are effectively a requirement.
etcd: How does it compare with Consul or ZooKeeper?
All three provide consensus-backed coordination. etcd has the simplest data model and the Kubernetes ecosystem behind it; Consul bundles service discovery, health checking and a service mesh; ZooKeeper is older, JVM-based and still common under Kafka and Hadoop-era systems.
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