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OCAU News |
So, today we had an outage for about 90 minutes as previously advised. This was a chance for me to give our servers (beer and bbq) a hands-on inspection to see how they're faring after a year or so of service. I'm happy to say they're looking fine, touch wood! I also replaced some memory in bbq that had failed a couple of months ago, so we're back to the full 8GB in that machine now. While I was in there I also whacked in two more CPUs. :)
It's actually slightly complicated to upgrade the machine to four CPUs. Firstly you have the Voltage Regulator Module (VRM) for each CPU, which slot into little brackets next to the CPU sockets.
  
Because we now have four CPUs we have to spread the memory out across four banks instead of only two, so we need to install two more memory VRMs, which sit in a special socket next to the RAM slots. While we're at it, best to install the third 550W PSU too, because in order to run four CPUs you need at least two working PSUs. Having three installed gives us redundancy in case one fails.
   
Then of course we install the CPUs themselves, attach the heatsinks and replace the cooling shroud over all four heatsinks. The shroud forms two tunnels with hot-swappable fan cartridges at each end, so even if one fan fails in each tunnel, both CPUs in that tunnel will still be cooled.
   
Firing it up was pretty unremarkable after all that (and lifting it back into the rack by myself, urgh). It detected four CPUs and 8GB of RAM immediately, as did Linux's kernel, and we were off and running.
Now, the reasoning behind this upgrade is that previously the HDD access on bbq was our limiting factor. Since we've been running MySQL replication to beer, that has been helped a lot. In fact it seemed during the last stress-test that CPU load on bbq would be the next bottleneck. I had recently bought an entire Celestica chassis as a spares machine for bbq, and in order to test it I bought two CPUs off Ebay, identical to the two we're running in the live machine. Now I've verified the spare chassis works fine, it seemed a good opportunity to upgrade the CPU power in the live chassis by adding these CPUs. So anyway, enjoy. :)
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All original content copyright James Rolfe.
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