Ask HN: How do DO/linode host their database?

I know all the cloud big names e.g. aws/azure provide managed SQL or noSQL service so that their VM user can access the database with relatively low latency although they are not necessarily be running on the exact same machine (but at least there is option we can host in the same data centre). But how are those DigitalOcean/Linode users hosting their database? it is possible we can run mysql etc the VM directly (i.e. we manage them ourselves) but their VM instances probably wont always be powerful enough to host a database? or we are typically running a lot of replicated instances to balance the load? cheers