I am thinking to use cloud memory store redis database with policy set to noeviction, sort of persistent database to serve the client. Wondering what could be the downside of this?
Of course we will keep instance memory on higher side to make sure incoming keys can accommodate. Are there any chances keys can lost while sort of infra restructuring or failover or patching happen at cloud provider end?
Thanks in advance
There are still chances that keys will be lost in case of unplanned restarts. Failovers only work during instance crashes or scheduled maintenance, and will not work on manual restarts. GCP also has two Redis tier capabilities. Only the Standard tier supports failovers.
Both offers maximum instance size of 300GB and maximum network bandwidth of 12Gbps. The advantage of having Standard tier is that it provides redundancy and availability using replication, cross-zone replication and automatic failover.
noeviction is only a policy that makes sure that all keys are not evicted and not replaced regardless of how old they are. It only returns an error when the Redis instance reaches maxmemory. It still doesn't cover other persistence features like point-in-time snapshot and AOF persistence, which unfortunately Memorystore doesn't support yet.
Since Memorystore does not cover your entire use case, my suggestion is to use Redis open source instead. You can quickly provision and deploy a Redis VM instance from the GCP Markeplace.
You can check out the full features in the documentation.