We have couple of indexers in distributed environment.
What would happen if I bring both the indexers down. Is there a data loss and I will miss all data coming in from the UF's? If so what is the best way to make sure I don't lose any new data?
To protect against the data loss from UFs to indexer server you can enable indexer acknowledgment capability on forwarders. With indexer acknowledgment, forwarders resends any data not acknowledged as "received" by the indexer.
Check below page for more details. If it's already enabled on UFs then you are good to go.