I've been hitting my head of the wall from the past few weeks dealing with dell support, so I figured I'd through it out to the community to see if there's some wise person out there, that can help.
Basically I have 5 servers on customer sites, carbon copies of each other. (Specs Below)
E5-2620v2 - Hex with HT
Raid 5 H710 512 Cache
4x 300GB SAS 15K
Server 2012 R2 Pre-installed by dell.
Each server runs two VM's DC/DB IIS.
No A/V on host, iscsi target for backup connected in the VM.
Basically the problem is that the server starts to crawl at a horrible speed, pinging between the VMs goes to 100+ms. Even with the VM's turned off the server(host) still crawls. Opening Hyper-v manager 30+ seconds.
Here's the "funny part" rebooting the server doesn't resolve the issue but turn the server (host) off for 30 seconds and boom its all good again.
Could be fine for a week or a month after the reboot, I'm thinking it might be something to do with a cache on the RAID card with queues filling up or something like that.
Check your BIOS settings. Dell's servers ship with DAPC enabled by default, which intentionally throttles your processor to save power. If you turn that to "Performance," then you should see some improvement.
Another thing to note is that there was an update to the BIOS released in the past few months to address an issue with the processor's performance. Try updating your BIOS to the latest version