On Thu, May 17, 2007 at 03:55:43PM -0500, Ron Johnson wrote: > Aren't there PCI heartbeat cards that are independent of the load on > the host machine?
Yes, there is more than one way to do this. My main point is to emphasise that you have to pay attention to the details -- all of them. It's especially important not to trust the vendor to get it right, because even if they sell a database product themselves, they may get it wrong. Some failure modes are nearly impossible to emulate in the lab (how do you cause a brand new working board to start flaking out as though it has some intermittent problem?). So you have to make sure that the thing can't wreck your data _by design_, and not just empirically. This means you have to understand all the technical details of how the thing works in order to know whether it is safe. I'm sure we've all seen, more than once, things happen that the vendor assures cannot. What this really comes down to is risk analysis. If you add a complicated failover system to get to five nines, and it breaks, it might actually make your uptime numbers worse, because it takes so long to recover from breakage. (If failover doesn't work, do you have to restore from dumps? How big is your data? Did this outage just go from five minutes to four hours?) Also, if it is complicated enough, your sysadmins have a whole new class of loaded foot-gun to fire at 03:00. So whatever you do, don't let your management talk themselves into specifying this on Thursday and deploying on Monday. A -- Andrew Sullivan | [EMAIL PROTECTED] Information security isn't a technological problem. It's an economics problem. --Bruce Schneier ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match