Nicolas Williams writes: > On Mon, Jun 02, 2008 at 10:03:28AM -0700, Richard Elling wrote: > > In most modern servers, "power off" in the traditional > > sense of "init 5" is not the same as "turn off the power to > > the server." I wonder if the customer is trying to solve the > > wrong problem? > > Also, shouldn't the UPS notice that the load is gone when the system > powers itself off? What's the point of telling the UPS "I'm almost done > powering off" when the UPS could just notice that you are, in fact, gone?
Frequently, UPS doesn't have just one load. It will also have: - local switches and routers - displays and other auxiliary equipment - other servers that act as slaves For that last one, the UPS software (when it starts the shutdown sequence) uses either some proprietary mechanism or SNMP to tell the other slave servers that they must also shut down. They're usually on their own, though, to get this done in time. (At least with the software I've used.) Worse still, someone could shut down one of the systems plugged into the UPS *without* intending to pull power for the other systems on the same UPS, so just looking for a delta won't do it. There's no good way for the UPS to know when to shut down. Has nobody else used APC's proprietary SmartUPS software or the open source 'nut' (Network UPS Tools; www.networkupstools.org)? -- James Carlson, Solaris Networking <james.d.carlson at sun.com> Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677
