On Sun, Aug 01, 2004 at 09:44:13AM -0700, Michel Py wrote:
In other words, I don't really care if the second processor reduces the MTBF from 200k hours to 60k hours, but I do care if the second processor reduces the time to restore service from 24 hours to 20 minutes (7.5 minutes for SNMP to fail the query twice, 1.5 minute for the tech to find out that either it's frozen or there's a BSOD, 6 minutes to have someone go there and reset, 5 minutes to reboot).
With the right form factor (nice easy-to-open rackmount unit) it will take just as little time to swap in an on-site cold-spare. That way you get the nice MTBF and the short restore time. Also, if you have multiple similar machines, you drastically reduce your spares inventory.
Unsignificant in my experience, and does not balance what Alexei mentioned yesterday: a duallie will keep the system up when a faulty process hogs 100% CPU, because the second one is still available. That also increases availability ratio.
These days you can achieve the same using hyper-threading for example, and keep the long MTBF :) -- Colm MacCárthaigh Public Key: colm+pgp@stdlib.net