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This blog is intended to provide information on debug issues encountered in Microsoft Support, such as STOP errors or hanging servers.

INFO: Capturing dumps of hung/frozen vms

INFO: Capturing dumps of hung/frozen vms

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150120: recently me and some colleagues have been seeing problems with vmss2core where created dmp files are 0 bytes in size. Looking at the comments section on it appears there are more people seeing this. I'm trying to get in touch with VMware to resolve this. This happens when converting 2012R2 dumps (for me and my colleague).


Hi All,

In Support we frequently use memory dumps as a tool to troubleshoot problems, such as a hung or frozen machine. Sometimes however, capturing a dump proves anything but trivial, and it may take extended amounts of time and effort to finally get the data we want. Now, when working with virtual machines, I still see engineers struggle with capturing a memory dump of a hung vm. However, both Hyper-V and VMware provide functionality to capture the machine state and convert the state file(s) - vsv/bin on Hyper-V, vmss on VMware -, to a dump file that can be read into WinDbg. Converting is simple: on Hyper-V use vm2dmp, on VMware use vmss2core (thanks to Paudie from VMware for sharing this link with me).

Let me know if this bit of info helped you!

Note: should you want to go the "old" way of getting dumps on vms, then you'll surely appreciate the virtual NMI functionality in Hyper-V 2012 R2. ;)


  • Thanks for the mention Rob.

    also from VMware side take a look @ KB

    This shows you the ins and outs of collecting a .vmss file (which is essentially a file generated on the Virtual Machines home directory when you suspend a Virtual Machine on ESX for example

  • How about use livekd?

    livekd -o memory.dmp -p -hv VMNAME

  • Indeed, livekd is another option. :)

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