On Mon, Jan 08, 2001 at 02:35:49PM -0800, Sean Donelan put this into my mailbox:
One issue with highly redudandent data centers is the failure modes are "interesting." You don't want to shutdown due to a single UPS failure, so you don't use something simple like PowerChute Plus. You most likely don't want to shutdown based on any automatic signal. However, you do want a way for an operator to gracefully shutdown a lot of equipment quickly when the decision is made.
It should be technically fairly easy to set up an 'Emergency Graceful Shutdown' button to live next to the EPO button; this controls a line that runs through the data center that activates either one relay per system or one optoisolator per system, depending on your fancy, that can raise or lower a particular serial line (DSR, CTS, whatever). You then install a daemon (again, fairly simple) that listens to this serial line; when it detects a change, it executes a graceful shutdown on that system. If you wanted to get fancy, pushing the "EGS" button could send a series of pulses that the daemon would have to interpret; this way you guard against odd line noise or loose connections triggering the shutdown. You could even set up a 'Cancel EGS' signal, as well. You could then interface this to more stuff, like the "You'll be out of diesel for your generator in 120 seconds" alert, etc. etc. Then again, my sprinklers water my lawn via a cron job, so I might just be Different. -dalvenjah -- Dalvenjah FoxFire (aka Sven Nielsen) "If her breath were as terrible as her Founder, the DALnet IRC Network terminations, there were no living near her; she would infect to the North Star!" e-mail: dalvenjah@dal.net WWW: http://www.dal.net/~dalvenjah/ whois: SN90 Try DALnet! http://www.dal.net/