We have VMWare virtual machine in data center but applications on it suddenly started to be slow after one weekend. We are considering possibility that data center has moved virtual machine to other physical server (with slower hard disk operations) or has started other processes on the physical server and those processes reduce the share of physical resources that are available to our virtual machine.

The question is - how we can check on the virtual machine that physical server is providing enough resources (RAM, CPU power, hard disk througput) whose limit is specified in the parameters of the virtual machine? We are satisfied with the network, but performance is an issue.

The VMWare parameters are vey low - Windows 2003 server, 1GB RAM, 36GB hard disk space, one CPU, but that is unimportant in our case. Task Manager shows that our application uses not so important amount of resources but nevertheless, the end user experience is bad due to low performance.

  • If you have performance graphs, I'd just send those to the hosting provider, asking if they know something about that. – Halfgaar Jun 21 '16 at 8:13
  • We have no performance graphs or other information ante factum. Users were satisfied and measurements were not taken. So, we can not make comparison. We can only see to that virtual machine receive sufficient resources. – TomR Jun 21 '16 at 8:24
  • You can perhaps look at the 'steal' time, if there is such a thing on Windows. It measures how much the vCPU waits for the hypervisor. As for IO; perhaps graph the latency together with IO ops/s and/or util percentage. – Halfgaar Jun 21 '16 at 9:46

I’ve recently heard about a tool ApexSQL VM Monitor which tracks virtual machine performance with graphical representation. You can use it to check CPU ready and see if maybe VM is ready but not being scheduled on physical CPU. Checking datastore read/write latency and read/write rate can help you to narrow down troubleshooting. Once you determine what is causing slow VM performance – CPU or datastore, you can set up alerting and be just-on-time alerted if VM comes low on resources again.

You may also try some alternative commercial tools like the one from ManagEngine, Paessler or SolarWinds

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