Best backend for scale? S3 vs MySQL

Hi guys,

I’m running a standalone Vault instance and am trying to decide on a backend that will scale well. I’d like to use vault as a KV store for both secrets and regular kv data (eg. config info). I know it’s not what Vault is designed for but it works beautifully and saves me setting up a separate KV store for a few extra variables.

My question is about which backend I should go with for that, at scale. I’ll eventually end up with millions of records. According to this thread: Question regarding preferred Storage Backend(s) for large k/v store (up to 50 million secrets) the in-memory options (eg. Consul) aren’t a good choice. I also don’t need any of Consul’s other features so it’d be overkill.

I’m leaning towards either S3 or MySQL - which would be a better choice for my use case? And which would maintain the best read/write performance once the number of records reaches the millions?