Convert VMware Snapshot into Memory Dump

Background 

This document explains about generating a memory dump for a VMWare Virtual Machine when the machine becomes unresponsive. VM becomes unresponsive for various reasons, you may not be able to get into any OS related settings or access any application. Even users may get not be able to access any shares or resources of this machine. In this type of situation Memory dump would be required to analyze the cause. Even if the OS is configured to generate a Memory Dump for System Crashes, it would not be able to generate a Memory Dump for System Unresponsiveness most of the times. But with a VMWare VM, you can take a snapshot of the machine when it is unresponsive and then use vmss2core.exe tool to convert the snapshot to a Memory Dump.

The target audience for this information is any technician that is responsible for creating and deleting snapshot in the Levi virtualization environment.

 

Note:- This document does not provide a solution for system unresponsiveness, this explains about converting VMWare Snapshot to a Memory Dump.

 

Steps

1. When the VM becomes unresponsive and gets into a deadlock situation, go to VMware vCenter or vSphere Client and take a snapshot.

Snapshot Naming Convention.

 

ECO Change Order related snapshots should consist of the following format:

nodel - {SERVERNAME}-{ Change Order #} {Date }

EXAMPLE: “nodel – DFWSQLBODEV01-CHG0078697 06-08-2016”

 

 

2. Locate the Snapshot files:

a) In vCenter, Right Click on VM and go to Properties. Browse the datastore where the VM is located.

b) Locate the folder with the same name as the VM.

c) In this folder locate the snapshot file. There will be a snapshot (.vmsn) and a memory (.vmem) file. e.g. nodel – servername-06-08-2016 ”with different suffixes (vmsn and vmem).

 

3. Save a copy of all files that are present (.vmsn and .vmem) for the snapshot. In vCenter, right click on the files, select Download and save them to a folder.

For LSA : Save .vmsn and .vmem file on daltseinfra4

For LSE : Save vmsn and .vmem file on brutseinfra01

For AMA : Save vmsn and .vmem file on sngtseinfra01

 

5. Remove the VM snapshot.

 

4. Download and copy the vmss2core.exe utility to the same location as the snapshot files. Please refer the following VMWare KB Article, http://kb.vmware.com/kb/2003941 for instructions. Link to download the vmss2core.exe is also available in the same KB Article.

 

5. Open Command Prompt and change the directory to the location of the snapshot files. Execute the following command:  vmss2core.exe -W virtualmachine-snapshot.vmsn virtual_machine_name.vmem  Note: If the OS in VM is Microsoft Windows 8/8.1 or Windows Server 2012, run this command:  vmss2core -W8 virtualmachine-snapshot.vmsn virtual_machine_name.vmem

 

6. Once the Memory Dump(Memory.dmp) is created, Windbg tool could be used for analysing it.

 

7. Ensure that the files are deleted from the terminal servers after analysis.