Error Code 8 usually means the server is running out of configured memory for aerospike.
There are three broad ways of configuring a namespace storage
- In-memory only
- In-memory with disk storage
- Disk storage only
Irrespective of the storage method, you have to ensure that there is always enough memory configured and available for aerospike process. Aerospike will not flush excess data or index to disk when memory is full. It will evict the data/index as applicable but will not dump out to disk.
Please confirm that you are running with the default high-water-mark values and the nodes have enough free memory.
Please note this error is independent of r3.2xl and r3.8xl. You might have seen this in r3.8xl because you would have put in more number of objects. Did you update the aerospike config in r3.8xl to increase the memory configured in the namespace section?