So far, for last 8 months, we have seen couple of SMPS failures and a motherboard. Also had issues with UPS batteries. We are learning and improving in component selections, which should further improve Failover is also managed at application layer by FOSS such as Cassandra, Hadoop, so user's have in general not faced much downtime. If we are not able to scale or manage, we will re-look and consider moving to public cloud.