Uniquely identifying one of an active active server pair

Question

I've got two servers in active active configuration sharing a clustered database. One operation will be to tidy up the database (e.g. delete old records etc) which I only want one server to perform at a time.

I am currently planning on writing a configurable value into the dB so that one server can id if the other server is working on the database. Is there a cross platform way to uniquely identify a computer so we don't need to have an extra configuration item? Any other ideas on how to implement this sort of cross machine mutexing?

Thanks