And yet another not-exciting blog entry. My VM host with an FX-8320 was on an AMD 760G board so it lacked IOMMU which I’d love to have for SR-IOV among other things. I have a spare machine laying around that was formerly a gaming machine. Needing more RAM (The 760G board only had two slots) and IOMMU, I decided to repurpose the gaming machine as the VM host. The 990FX based board already had an FX-8120 in it, so I took a single step back in CPU generation but it’s fairly close. I only had 8GB of RAM in the old setup, so I combined that with 2x2GB sticks of ECC DDR3 RAM I had hiding in a box. I have a bit of head room now and can launch a few more VMs with 12GB of total RAM. While that’s not impressive as far as virtualization host hardware goes it does let me run a bunch of local services for testing/learning/re-learning. Not having onboard graphics with the new board necessitated the use of another video card, luckily I had some GTX 750 Tis laying around (I seem to lay ‘laying around’ about hardware pretty often) so one went in the bottom PCI-E x4 slot so as to not block any other slot for future upgrades. The Intel I350-T2 card went in the next x4 slot for iSCSI.
VM storage is going to be split off from the hardware, so it will all be through iSCSI with MPIO. That pretty much just leaves me with a ton of PCI-E slots for NICs.
I was able to reduce reported CPU TDP by offlining the “odd” cores (1/3/5/7) while load is low (better to offline these cores as 01, 23, 45, 67 are shared in AMD’s CMT architecture), locking the CPU at idle and reducing power state 6 (idle) voltage from 0.9375v to 0.825v which has been stable so far (sensors reports 0.85v). Power tends to stay close to 30w and never breaks 50w. If it was more heavily utilized I’d let it clock up, but nothing is CPU limited at the moment. I’ll have to try monitoring power usage at forced idle vs the ‘ondemand’ governor with various load transition points. I wouldn’t call anything sluggish, but I don’t have hundreds of devices on my network.
As for a power supply, the case already had a SeaSonic 660XP2 80+Platinum power supply, so even if I do have to run the CPU at full tilt there should be little waste in the PSU department. It’s completely overkill both for being Platinum at this power level (likely sub 100w at all times), and for its 660w rating. If I was going to buy something I probably would’ve got a SeaSonic Gold which would still allow me plenty of headroom even if it was full of NICs and RAM. It does feel a little safer than running off a 180w power supply with an FX-8320 and a drive array, though.
There’s plenty of local services running here, eventually I’m going to make some (counter)intuitive web GUIs for configuring stuff (ie IP Address Management which then configured DHCP/DNS).. so it was good to brush up on configuring these things from scratch.