Updated: April-20
Elasticsearch Version: 1.7-8.0Background
Before you begin reading this guide try our beta Elasticsearch Health Check-Up it analyses JSON’s to provide personalized recommendations that can improve your clusters performance.
To troubleshoot log “Lock assertion failed” it’s important to understand a few problems related to Elasticsearch concepts node. See bellow important tips and explanations on these concepts
Overview:
Elasticsearch stores its data (shards, cluster state, etc.) on the file system and uses the path.data (config) to determine its data store location. There can be more than one Elaticsearch installation on the same node (host), and this error is thrown at startup time as part of the bootstrap checks to make sure there is no data corruption.Potential causes for this error:
- Multiple Elasticsearch installations using the same data location.
- The node.max_local_storage_nodes setting is not set properly in the case of multiple Elasticsearch installations using the same location.
- An existing orphaned Elasticsearch process is already running, which uses the same location, and you are trying to start the new process.
- Elasticsearch doesn’t have write access to the data folder.
Exception message:
maybe these locations are not writable or multiple nodes were started without increasing [node.max</span><i><span style="font-weight: 400;">_local_</span></i><span style="font-weight: 400;">storage_nodes] (was [1])
Troubleshooting steps:
- If you do not have multiple installations on the same machine, check if there is already an Elasticsearch process running by using ps aux | grep elastic, on *nix based system, and kill the process if it is not needed.
- To allow for more than one node (e.g., on your development machine, not recommended in production), use the setting node.max_local_storage_nodes and set this to a positive integer according to your requirement. Find more info in this official doc.
- Ensure the Elasticsearch process has write permission for the path.data location.
Disclaimer:
node.max_local_storage_nodes setting is deprecated in 7.x and will be removed in version 8.0.Nodes in Elasticsearch
What it is
Simply explained a node is a single server that is part of a cluster. Each node is assigned with one or more roles, which describes the node responsibility and operations – Data nodes stores the data, and participates in the cluster’s indexing and search capabilities, while master nodes are responsible for managing the cluster activities and storing the cluster state, including the metadata.
While it’s possible to run several Node instances of Elasticsearch on the same hardware, it’s considered a best practice to limit a server to a single running instance of Elasticsearch.
Nodes connect to each other and form a cluster by using a discovery method.
Roles
Master node
Master nodes are in charge of cluster-wide settings and changes – deleting or creating indices and fields, adding or removing nodes and allocating shards to nodes. Each cluster has a single master node that is elected from the master eligible nodes using a distributed consensus algorithm and is reelected if the current master node fails.
Coordinator Node (aka client node)
Coordinator Node – is a node that does not hold any configured role. It doesn’t hold data, not part of the master eligible group nor execute ingest pipelines. Coordinator node serves incoming search requests and is acting as the query coordinator – running the query and fetch phases, sending requests to every node which holds a shard being queried. The client node also distributes bulk indexing operations and route queries to shards copies based on the nodes responsiveness.
Log Context
Log”Lock assertion failed” classname is NodeEnvironment.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (!closed.get() && locks != null) {
for (Lock lock : locks) {
try {
lock.ensureValid();
} catch (IOException e) {
logger.warn("lock assertion failed"; e);
throw new IllegalStateException("environment is not locked"; e);
}
}
}
}
Related issues to this log
We have gathered selected Q&A from the community and issues from Github, that can help fix related issues please review the following for further information :
1 Elasticsearch, Failed to obtain node lock, is the following location writable
38.79 K ✔502 elasticsearch fail to start gives erorr
3.97 K✔ 4About Opster
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