What are the functions of the master node role?
- Coordinates the clusters
- Keep track of the data
- Make sure data is balanced
- Coordinate traffic
What is the role of a data node?
- Store the data
- Perform the index and search operations
What is an index in elastic search?
It’s the abstraction where you documents are stored and indexed.
What is a primary shard?
The primary location where documents are stored and retrieved.
What is a replica shard?
- A copy of a shard that is maintained into a different node and can be promoted to “primary” in case the current primary goes offline.
What is a shard?
Shards are blocks of data that are distributted cross nodes to balance the data.
Draw a diagram the elastic architecture with the basic concepts.
What is the basic unit of storage in elastic?
A document.
What is a document comprised of in elastic?
It’s a json object with arbritrary number of fields.
What are the 3 states an index can be in?
- Green
- Yellow
- Red
How are Indexes organized?
They are split into:
* Primary shards
* Replica shards
What does a GREEN index mean?
All primary shards and their replicas are online (All data is available with replication).
What does a YELLOW index mean?
The index is missing replicas. (All data is available, but we don’t have a “backup”)
What does a RED index mean?
A primary shard is missing. (Data is missing)
