[troubleshooting guide]: On Redis Cloud the maxmemory ceiling is the database's size limit, so you cannot just CONFIG SET a bigger one. Either enable an eviction policy (allkeys-lru on a cache, volatile-lru when only some keys have TTLs) so writes stop failing, or resize the database to a larger size in the Redis Cloud console. Monitor with INFO memory and alert on used_memory over 80 percent of the limit so the next fill-up is planned, not discovered.

Context: Writes to a Redis Cloud database fail with OOM command not allowed when used memory > 'maxmemory'. The database has hit its storage limit.