I have implemented a Custom CacheStore for Ignite to communicate with Elastic Search. Now, if ElasticSearch server is down for some time, will the data in the cache be uploaded to Elastic Search once the ES server is up?
Does Custom CacheStore for Ignite automatically do write-behind?
No. It is disabled by default: https://apacheignite.readme.io/docs/3rd-party-store#section-configuration
setWriteBehindEnabled(boolean) | Sets flag indicating whether write-behind is enabled. | false
Now, if ElasticSearch server is down for some time, will the data in the cache be uploaded to Elastic Search once the ES server is up?
No. Ignite will not send that data again. It is also specified in documentation:
Performance vs. Consistency
Enabling write-behind caching increases performance by performing
asynchronous updates, but this can lead to a potential drop in consistency as
some updates could be lost due to node failures or crashes.