Running a large number of keyspaces in a cluster

What’s the operational experience like with large numbers of keyspaces in a cluster? Are there any functional or operational limits to be aware of?

It’s recommended to limit the number of keyspaces/tables in a single cluster to a few hundreds.
Using more can be tricky in some cases as Scylla needs many files, and Memtable flush is per table. Additionally, the amount of RAM available and how homogenous those keyspaces are homogenous also have an impact.