We've been running DRBD, the Distributed Replicated Block Device on two pairs of machines for over six months now, without a single glitch. As predicted, the support contract was unnecessary. :-) The first cluster (for which the contract was purchased) runs a couple of mail servers, with Exim, Dovecot and OpenLDAP on them and has been up and running since January. The second cluster was acquired a couple of months later and hosts some busy MySQL servers on it I am extremely satisfied with the results so far. Only one small SNAFU that happened yesterday whilst relocating half an e-mail cluster to a 45km distant data center: it appears that several files are missing. Three users complained of messages not having arrived... I'm still investigating, but it appears that (if at all), the situation was caused by human operator error in getting the two DRBD halves back together.