Current situation with garbage collection

[Mitsos]

@Alexey

?! never saw this. Could you please show, where is it proposed?

Allow to merge two nodes into one

By the way, I think we can detect nodes with 0B advertised space and treat them as unhealthy to allow the repair worker to move data from them in case if amount of healthy pieces would be lower than a repair threshold. This basically may work as a partially GE.