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arod
Asked: 2010-06-10 14:55:01 +0800 CST

is there anyway to know if your supposedly fully dedicated server is really a virtually resource-shared machine? [duplicate]

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sometimes I feel my server not responding as smoothly as I would expect (i have a Intel(R) Xeon(TM) CPU 2.80GHz Quad Core), given that for example, the 'top' commands reports a low load < 0.5, CPU are almost completely idle ...

I maybe have internet connectivity issues, so I don't really know if it's me or if it's the server itself.

Is there anykind of benchmarking script (or something analogous) I could run and see the actual performance of the server ?

central-processing-unit performance benchmark

5 Answers

  1. The virt-what script will identify many different types of hypervisors and container technologies. It's pre-packaged for most major Linux distributions (e.g. apt-get install virt-what or yum install virt-what) and its output is suitable for use in shell scripts. It correctly performs its detection from inside the virtual guest.

    Current types of virtualization detected:

    • hyperv Microsoft Hyper-V
    • kvm Linux Kernel Virtual Machine (KVM)
    • lxc Linux Containers
    • openvz OpenVZ or Virtuozzo
    • powervm_lx86 IBM PowerVM Lx86 Linux/x86 emulator
    • qemu QEMU (unaccelerated)
    • uml User-Mode Linux (UML)
    • virtage Hitachi Virtualization Manager (HVM) Virtage LPAR
    • virtualbox VirtualBox
    • virtualpc Microsoft VirtualPC
    • vmware VMware
    • xen Xen
    • xen-dom0 Xen dom0 (privileged domain)
    • xen-domU Xen domU (paravirtualized guest domain)
    • xen-hvm Xen guest fully virtualized (HVM)

    The Puppet tool facter uses virt-what internally to determine the type of virtualization in use, so if you are using Puppet, you already have this installed.

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  2. On Linux, it is possible to look for tell-tale signs of virtualisation depending on the type of hypervisor used. You can typically start by looking in /proc/cpuinfo for the CPU type. Some hypervisors report fake CPU types such as "QEMU Virtual CPU". If it is running VZ, you can find /proc/user_beancounters that report resource usage. With Xen, you will find a /proc/xen directory.

    So, it is possible to guess if you are running under some sort of virtualisation.

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  3. If you can run perl scripts (depending on your OS), there's one called imvirt which can detect quite a few based on various system info (/proc/cpuinfo, dmidecode, etc.) - it sounds like you're on ubuntu, so there are packages for Jaunty, Karmic and Lucid, or you can grab it from Sourceforge.

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  4. There are things that were looked at by the antivirus companies for detecting blue pill virus variants.

    Basically it's extremely hard for a VM to match the real time clock with the CPU counters. If you have access to install a driver, you should be able to put the system into no interrupts and watch the counters. If you have a virtualised system then your clock will drift in chunks when the VM is switched out by the hypervisor (which is supposedly impossible based on the interrupt bit).

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  5. Look for steal cpu cycles. You can get this in top for example. "If your VM displays a high %st in top (steal time), this means CPU cycles are being taken away from your VM to serve other purposes."

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