The last data centre I worked in certainly had water sprinklers too. The gaseous system was one-shot. If the fire continues or restarted, or another fire occur

The last data centre I worked in certainly had water sprinklers too. The gaseous system was one-shot. If the fire continues or restarted, or another fire occurred before the system was recharged, water sprinklers would save the building. Redundant systems. Of course, some data centres probably have redundant gaseous suppression too.