[mslot]

The answer is mostly the same as for PostgreSQL, since Citus stores data in regular PostgreSQL tables.

It's a good idea to set up archival into blob storage / S3 using a tool like WAL-G for disaster recovery purposes, and streaming replication using a tool like Patroni.

(Or use a managed service like Azure Cosmos DB for PostgreSQL)

If a node is down and cannot be quickly recovered then the remaining shards are still available for reads and writes, except for DDLs.