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Es werden Posts vom Februar, 2014 angezeigt.

Hyper-V High Ping Latency

Had an interesting issue today, an insanely slow, brand new server….. or so I thought. First a bit of background on the client, they are fairly large, with over 400 client access devices to maintain, not including server, network equipment etc. to support this the client has 3 servers, one purchased a year and the oldest one thrown out, keeping all devices in warranty and with modern powerful equipment to keep things running, in addition to this there are two other servers that are replaced every three years, these are treated differently as these are speciality servers, and only do one task.

So, building a new server for a client, in this case a HP ML350p gen8 with Windows Server 2012 R2 STD running as a Hypervisor, nothing special in that, I do this exceedingly regularly so it has become more of a routine build for me. What got me with this one though was during testing I was getting insanely high ping latency, not only to the virtual machines from the network and vice versa, but als…

High Ping Latency in Hyper-V Virtual Machines

While working on a Hyper-V 3.0 deployment recently, I noticed that all of the virtual machines running on all newly built hypervisors were showing an unhealthy high ping latency trying to ping anything on the local network. Pinging the same destinations from the hypervisors resulted in perfectly reasonable 1ms ping times, but pings from inside the virtual machines varied from 1ms all the way past 200ms.

I started digging, thinking initially that it was just a clock synchronization issue that we saw on AMD as well as Intel chips, specifically on HP DL servers, in Windows Server 2003 days. The issue is not very well documented but one of the few Microsoft articles that attempts to explain it here. Solution to that issue is to add /USEPMTIMER switch to the boot.ini file. It used to fix negative ping times on AMD chips as well as lengthy ping times on Intel chips.

Windows Server 2012 does not have a boot.ini file obviously, so the way to add this switch is to issue the following command in …